The Desert Finder

Guest Post by Willis Eschenbach

Despite doing lots of research and investigations over the last few weeks, I’ve written little. Well, actually, I’ve published little, although I’ve written a lot. But I didn’t publish what I’d done, there was no wonder in it, no awe. So I tossed it all out and started “simply messing about”, as the Toad had it. For no apparent reason, I got to looking at the various methods for estimating the downwelling longwave radiation (DLR) based on surface conditions. DLR is the radiation emitted by the atmosphere which is directed downwards towards the earth. There’s a good summary of the various DLR estimation methods here.

In any case, I wanted to compare the estimated DLR to the DLR from the CERES satellite observations. I used the “Brunt” method, which calculates an “effective emissivity” from the vapor pressure. The vapor pressure in turn is calculated from the surface temperature. I subtracted the satellite observations from the Brunt estimate. Figure 1 shows the result.

calculated dlr Brunt minus ceres dlrFigure 1. Difference between the downwelling longwave radiation (DLR) as calculated by Brunt, and the downwelling longwave radiation dataset from the CERES satellite data.

I busted out laughing when I saw that graphic come up on the silver screen. I do my science visually, by painting the transformations and relationships in color. And in general, I have only the vaguest idea of what any given graphic will look like before it is displayed. So watching the graphics appear onscreen is like opening a line of scientific presents. Each one is unexpected, each one reveals new things.

This one was funny to me because it was such an excellent and detailed map of the desert and arid areas of the planet. From the Sahara to the Atacama Desert, the Gobi, the American Southwest, the Arabian Peninsula, the Namib Desert, it’s all laid out in precise detail. Heck, you can even see the green areas of Australia as a thin strip along the east and north coasts.

This is a curious result because the CERES satellite doesn’t measure water vapor … but what we have in Figure 1 is a map of water vapor. Over the desert areas we get less downwelling radiation than the estimate suggests, because water vapor is the main greenhouse gas. In the desert the air is so dry that more radiation escapes to space, and less is absorbed and radiated downwards (and upwards) by the atmosphere. It also shows the moistest areas of the planet (dark green and blue). These are in the equatorial tropical forests, where transpiration combines with evaporation. This leads to lots of water vapor, and a concomitant increase in DLR above what the estimate suggests.

This is the first time I’ve looked at the difference between a variable in the CERES dataset and an estimate of that variable. They say that all models are wrong, but some are useful. This model of downwelling longwave radiation is obviously wrong … but it’s useful because of exactly where and how much it is wrong.

Which leads to the final surprise for me, which was the size of the deviations from the expected DLR. From very dry regions to very wet regions is a range on the order of 100 W/m2 of downwelling LW radiation … I didn’t think it would be that big.

Anyhow, that’s the kind of thing I like to write about—the unexpected. For me, the adventure of science is never knowing which bush might be the one that hides the rabbit …

Regards to everyone,

w.

As Always: If you disagree with someone, please quote their exact words so we can all understand your objection.

A note on the Brunt Method: The Brunt method estimates the “effective emission” as a function of the form

a1 + a2 * sqrt( vapor_pressure )

Per the above citation, the canonical values for a1 and a2 are 0.51 and 0.066.

When I fitted the values, I got a1 and a2 as 0.65 and 0.029. I thought this might be a result of including the ocean. So I looked at just land, which gave a1 and a2 as 0.65 and 0.024. And looking at just the ocean I got 0.66 and 0.030. None of these are near the values given in the reference. However, they work quite well, and the canonical figures give much larger errors. Go figure.

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349 thoughts on “The Desert Finder

  1. Kind of obvious point but if water vapour is the largest “greenhouse gas” and desert areas, where there is the smallest atmospheric concentration of it, achieve the hottest day time surface temperatures of planet, doesn’t this say something important about the whole concept of “the greenhouse effect”?

      • Wicked, these areas get this hot during the day because of their latitudes. Most of these deserts sit in areas that have a 1 – 2 punch, the atmosphere generally stays in a high pressure mode causing subsidence and a adibiatic warming. So not only is the air warming as it descends in these latitudes but there is a lack of cloud cover to block solar energy. I could further develop how most deserts form on the eastern sides of oceans but it leads to the same outcome, cold eastern ocean currents have less evaporation which leads to less cloud cover… a 1-2 punch. Then at night comes the ‘Greenhouse effect’, since there is very little water vapor, the most important greenhouse gas. There is very little trapping of the outgoing LW radiation and subsequently at night when solar energy no longer warms the surface there is a lot less down welling LW radiation. Which is the point of Willis’ s essay.

      • SOME deserts are famous for getting very cold at night. While its true that deserts heat and cool faster than moist areas that have cloud cover some remain quite warm at night. While I have shivered in below zero C temperatures in central Australia I have also sweated buckets trying to sleep in a motel in Beatty Nevada with air temperatures higher than 30 C at midnight.
        Then there are the Antarctic deserts where the MAX summer temperatures get close to zero C but winter temperatures drop to -30 C and coupled with adiabatic winds that can hit 200 mph even a native of Wisconsin would admit to it being a mite chilly.

      • There isn’t a lot of downwelling LW during the day either.
        Anyone near one of these places they can measure the IR temp of the clear sky? Where I’m at even during the day the sky is very cold when it’s clear and dry out.

      • Brian – your 1-2 punch is right on the money. The cloud cover, regardless of the absolute humidity, is going to be minimal when there is a preponderance of descending air.
        Clouds mostly warm the surface at night and these are generally absent. The high daytime temperature invites some mechanism, ANY mechanism, to keep some heat in during the night. Nada. Just a smattering of CO2 and a dark night sky.
        The temperature of the surface is far higher than the hot desert air. I wonder if this has been well considered. A cubic metre of air doesn’t hold much energy, let’s say in round numbers = 0.0012 MJ/K. The sand mass heated and cooled holds about 1 MJ/K per sq M of surface. The loss of heat into the sky from a sq km of desert surface is maybe 2×10^13 J per night. The Sahara loses about 10^20 J per night from the surface, by radiation I suppose.
        Willis you are really onto something. I find the map astonishing. Completely unexpected. My knee-jerk response is that the loss of heat from the (very hot) surface has to be modelled in cells and the humidity of the air over each cell considered.
        Atmospheric dust may be very important when making the calculation because a lot of the time the Sahel, for example, has a completely unseen sun on bright, cloudless days. One cannot even see where the sun is, the obscuration by dust is so complete.
        Viva measurements! Viva!

      • Bit of a myth that hot deserts always get very cold at night.
        Night time temperatures can be below freezing during “winter” when the daytime maximum might be around 25C .
        However when the daytime maximum is 45C or higher the minimum might be 30C….generally not considered as very cold.

      • Steve P,

        I think it depends on the desert.

        Well sure. It’s almost always freaking cold in Antartica.

        It is currently 98°F in Palm Springs, CA, with a forecast high of 99° for today and 66° for tonight.

        Mmmhmm. Of course one evening’s weather isn’t going to tell us much about climactic factors. Mean diurnal temperature range in Celsius by calendar month:
        Month Palm Springs Sahara Amazon
        1 15.16 16.31 9.39
        2 15.77 17.20 9.32
        3 16.60 17.28 8.98
        4 17.93 17.08 9.99
        5 18.57 17.05 11.01
        6 19.57 16.59 12.60
        7 16.57 15.42 13.90
        8 15.98 14.26 14.42
        9 17.12 15.25 12.87
        10 17.44 15.99 12.13
        11 16.22 16.31 10.47
        12 15.06 15.74 9.75
        ann mean 16.83 16.21 11.24
        Using data from CRU TS3.22 Tmax-Tmin available on KNMI climate explorer. “Palm Springs” is the 5×5 grid containing the city. “Sahara” and “Amazon” are both 15×15 grids which I chose by eyeballing a map.

      • I’ve worked in the deserts of southern Algeria, Egypt and western Oman. By day, these places are the hottest on earth in summer with weeks on end having daily maxima in the mid 50 degC (in Oman). They do not get very cold at night after a hot day unless you consider 30 degC cold. That is a 25 degC swing. In about 6 years in these places I never experienced a cold night after a hot day unless a new weather system moved in. In winter the nights after mild days are cold and they feel a lot colder because the humidity is normally very low. Having also worked in central Australia for many years I can assure everyone that summer temps there are a few degrees less than the other deserts mentioned above and the following night temps are correspondingly a bit less. The biggest swing in temperatures I ever experienced were in central Siberia at Novosibirsk where after a low 30’s degree C day there were snow flurries at night – this area was not a desert.

      • 4 eyes,

        I’ve worked in the deserts of southern Algeria, Egypt and western Oman. By day, these places are the hottest on earth in summer with weeks on end having daily maxima in the mid 50 degC (in Oman). They do not get very cold at night after a hot day unless you consider 30 degC cold.

        I don’t consider that cold. It’s not the comparative which illustrates the principle …

        That is a 25 degC swing.

        … that is the comparative which does. So again, the average annual climatological mean diurnal temperature ranges for Palm Springs, the Sahara and the Amazon are 16.83, 16.21 and 11.24 degrees Celsius respectively. In the Amazon, nightly temperatures are not as cool relative to its daytime high as the desert regions cited — to the tune of 5°C — because the Amazon has far more absolute humidity and cloud cover. Of those, clouds are the more noticeable radiative effect, something I learned about on cloudy winter nights in southern Ohio — they block a hell of a lot of outgoing IR and “bounce” it back toward the surface, resulting in a smaller net rate of heat loss at night.
        It’s only a tendency though. There are other effects from how air masses move around which may or may not affect cloud cover any particular evening — think frontal systems, inversions, etc. — but which do have an effect on that night’s temperature. The radiative effects are most detectable and predictable in long-term means.
        Amazon vs. Sahara are two good examples because they’re such distinctly different climates despite being at similar latitudes. The Sahara’s annual mean temp is about 30 °C. The Amazon, 27°C — even though it’s about 5 degrees closer to the equator. Two main reasons for that: clouds during the day in the Amazon reflecting incoming sunlight, and more surface evaporation. After the sun goes down is where the radiative effects of heat loss come into play. That shows up very clearly in the long term mean diurnal temperature swing.

        • Brandon, I dug through the weather data I have and tried to select the period with the largest min-max-min solar day swing in temps. I did try to exclude “weather” and did things like required high pressure, low wind speeds, and a wide range in temps, it pulled about 250 records out of 122 million, the swings were right around 30-40F maximum.
          This link to Kevin Kilty’s blog has a report of someone dying of exposure on a reasonably warm day.

          The natives in many dry climates can make ice at night, even when the air temperature remains near 55°F, by exposing a shallow earthen dish of water on a high piece of ground to a clear, dry, night-time sky. In July 1995, my brother found a dead person lying atop a hill. He, too, had been exposed to a clear, dry, night-time sky; and the sheriff concluded that the person had died of exposure on a night when the air temperature in all likelihood stayed near 50°F all night. What do these have in common?

      • The Sahara’s annual mean temp is about 30 °C. The Amazon, 27°C

        More water vapor in the Amazon atmosphere is conducting more heat away.

        someone dying of exposure on a reasonably warm day.

        50 is not warm compared to 98.6. There is no mystery about dying of exposure in 50 degree weather. With no energy input, and enough time, a delta T of 48.6 will take it’s toll.

      • VikingExplorer,

        More water vapor in the Amazon atmosphere is conducting more heat away.

        Especially during the day. Isn’t that more or less what I wrote?

      • micro6500,

        Brandon, I dug through the weather data I have and tried to select the period with the largest min-max-min solar day swing in temps. I did try to exclude “weather” and did things like required high pressure, low wind speeds, and a wide range in temps, it pulled about 250 records out of 122 million, the swings were right around 30-40F maximum.

        Yes, to really isolate the radiative effects, you have to control for all sorts of other factors. That’s one reason why Willis used a CERES clear-sky product — to control for the effect of cloudiness. And lack of clouds is one big reason why hot deserts tend to have large diurnal temp swings. I’d think that’s generally the biggest reason.
        What data were you scanning? Is this Sahara only, or worldwide?

      • micro6500,

        Same world wide ncdc gsod data.

        Gotcha.

        One of the big reason I got my own weather station was to see if I could tell clear skies from data.

        Something I’ve found very useful for that exercise: http://wattsupwiththat.com/2014/11/25/a-first-look-at-surfrad/
        My vote for best Willis Eschenbach post, and second-best WUWT post EVAR. First place is actually a tie:
        http://wattsupwiththat.com/2013/05/27/new-wuwt-tv-segment-slaying-the-slayers-with-watts/
        http://wattsupwiththat.com/2013/05/28/slaying-the-slayers-with-watts-part-2/
        You lot don’t always make me want to tear my hair out, donchaknow ….

        • Brandon, Willis,
          This quote:

          I don’t know why, but I wasn’t exactly expecting that … which is the best part of science. I love surprises, the unexpected, and climate science is chock full of those. I mean, I knew that downwelling radiation was a function of air temperature … I just didn’t expect the alignment with the underlying surface temperature to be so exact. Other than the atmosphere starting to cool a bit earlier in the day than the ground (as we’d expect from the relative masses) they match up perfectly.
          Now, seeing how good that match was, I got to wondering how well that fits the theoretical profile that we’d expect from the Stefan-Boltzmann (S-B) relationship. This relationship says that infrared radiation is equal to emissivity times the Boltzmann constant times the temperature to the fourth power. I figured that using that formula, I could calculate an approximate value for the emissivity from the data with a simple linear analysis.
          Now, here’s the curious part. When I did that, I got an emissivity of 0.590 … which from everything I’ve read is too low.
          So I thought, well, that kinda makes sense, because the temperature up where the radiation is coming from is cooler. But how much cooler?

          Goes with what I’ve been saying about what my IR thermometer reads when pointed up.
          But I think I’m changing my mind about the absurdity of DW LW IR being ~300W/m2, because within a few days, I can have clear sky days with a 20-30F difference in average air temps, and it’s not solar, as it’s only days apart. So it has to be from the air. And I can “see” humidity in 8-14u, so I would expect in the SURFRAD mississippi location the sky is probably 30F, as opposed to the -60 to -70 I can go out and measure here (if the sky was clear).
          I always assumed I was measuring the average temp of molecules where the non-radiating gasses KE was shared with in this case water, and I was seeing the average KE of water in 8-14u the general temp of those gases. I also felt this was reasonable because you can use this same cold sky to freeze water when it’s above freezing.
          But if the air mass itself that is 41F right now, that will warm some today, and cool some tonight, but will be only a little warmer tomorrow (dur to a longer day than today), how does that air mass cool if it’s invisible in the 8-14u IR band (and yes i know where this is leading, that’s why I’ve explained as much as I have here)?
          I think someone calculated the thermal mass of the non-radiating atm as about the same as the surface mass that’s exchanging heat at about the same mass?
          Makes me think, and that’s a dangerous thing to do.

      • 4 eyes
        “Weeks on end in the mid 50’s”
        Sounds like wild exaggeration to me to put it politely. The hottest temperature officially recorded anywhere in Oman is 50.8 deg C Perhaps your thermometer was close to the outlet from your air conditioner. Most towns in Oman have a diurnal range of 10 to 12 degrees in summer – typically low 40’s to around 30. It may be a couple of degrees more in a rural location admittedly but hardly 25

    • Deserts have large variations between daytime and nighttime temperatures because dry air has a low heat capacity compared to moist air.

  2. Kind of obvious point but if water vapour is the largest “greenhouse gas” and desert areas, where there is the smallest atmospheric concentration of it, achieve the hottest day time surface temperatures of the planet, doesn’t this say something important about the whole concept of “the greenhouse effect”?

    • Thanks, Wicked. We’re looking at clear-sky conditions in the map above (no clouds). Desert areas get very hot during the day because they don’t have many clouds. The effect of this is much larger than any decreases in daytime downwelling longwave.
      And they get very cold during the night because there’s little water vapor to absorb radiation and leave the earth warmer.
      So no, they don’t say much about the greenhouse effect.
      Regards,
      w.

      • Funny, because it certainly looks like more conventional forms of heat transfer through different mediums, than conforming to “back radiation” or other “greenhouse” attributes. Different densities and mass affecting speed of absorbtion and conduction and the like. Deserts heat up faster and cool down faster. Mean temperature? Similar to non desert areas of similar latitude and altitude. So where is the “greenhouse” evidence?

      • POI, There are stories, anecdotal I accept, of British troops in the Sahara during WW2 suffering from frost bite during the cold nights! I am sure there may be some of American troops serving there too.

      • Wicked I tend to agree with you.
        One obvious point is how much energy is there in the atmosphere. When it is dry, the atmosphere contains little energy, and hence such energy as there is is quickly lost. This is the dry desert night scenario.
        On the other hand when the atmosphere is humid, the atmosphere contains a lot of energy and hence it takes time for the atmosphere to lose this energy, and hence night time temperatures fall away slowly. Thiis is the cloudy night scenario seen in most latitudes outside the tropics.
        Thise that consider that how we experience daytime/nightime temperatures is a matter of radiative energy, and back radiation thereof, fail to look at the obvious, namle how much humidity and hence how much energy is entrapped in tyhe atmosphere itself.
        Where I live (the shores of the Mediterranean) cloudy nights in summer are usually cool whereas clear sky nights in summer are usually warm. It would appear that is largely a matter of daytime humidity.

      • Thank you Richard.
        When we actually consider the MASSIVE changes in humidity that occur in any location daily or the MASSIVE differences of humidity between locations with similar latitude and altitude and see the TINY differences in mean temperature that these changes make (especially if you compare temperatures of a specific day of the year at a specific atmospheric pressure as well), I’m amazed that the Greenhouse theory gets the traction it does.
        That said, the principle of Occams Razor is the one scientists of any persuasion find hardest to apply. What use is your expensive degree (Preconceived Hypothesis Disorder) and how can you be paid as an “expert” if answers are simple and can be understood by anyone who managed to get into high school?

      • Never mind IR. I see “downwelling” visible light all day long: I see the sky.
        The narrative has it that visible light comes from the Sun, some is absorbed and the rest reflected to space: if that were true, the sky would be dark.

      • wickedwenchfan
        March 28, 2015 at 7:18 am
        … , the principle of Occams Razor is the one scientists of any persuasion find hardest to apply. What use is your expensive degree (Preconceived Hypothesis Disorder) and how can you be paid as an “expert” if answers are simple and can be understood by anyone who managed to get into high school?
        __
        Maximum giggle induction points awarded.

      • @Sleepsalot
        Yes. I worked on the desert for 20 years in Yuma until I retired 5 years ago. There were afternoons when the sky was so dark it looked like you photoshopped it in pictures. If fluffy white clouds were present the bottoms were saturated with the reflected desert light and the effect was even more unreal. One of those afternoons a test engineer pointed his pyrometer at the dark rocky ground and discovered it was 145 degrees F. No wonder my feet felt hot and wet with sweat.
        In the last ten years the sky seems to have become a less saturated blue on any day here in Yuma. I’ve seen some explanations of what may be the cause, but I don’t have the science background to really evaluate them.

        • The only possible variable is water vapor, and the PDO started to change about then, changing the path of the jet stream, probably not a coincidence with your changing sky.

      • wickedwenchfan,
        You’re right. It does say something about the ‘greenhouse effect’. The atmospheric ‘greenhouse effect‘ is after all supposed to make the surface below warmer (its temperature higher) ON AVERAGE. Clouds allegedly contribute significantly (~25%) to this atmospheric ‘greenhouse (average, net warming) effect’.
        Problem is, the AVERAGE (annual) sfc temps in tropical/subtropical desert and generally dry areas are consistently higher, not lower, by several degrees (corrected for altitude) than the ones in tropical/subtropical rainforest and generally wet areas.
        And this is in spite of the fact that the surface in those dry areas absorbs on average about the same amount of solar radiation that the surface in those wet areas does (‘All Sky’, according to CERES), while at the same time radiating back out a lot more – the mean ‘dry’ sfc temperature is higher than the ‘wet’, so mean blackbody emission (UWLWIR ‘flux’) is more intense (by perhaps 10-20 W/m2; ‘All Sky’, CERES), coupled with a much less intense atmospheric DWLWIR ‘flux’, making up a considerably larger sfc ‘net radiative (radiant heat) loss’ flux in the dry areas than in the wet (by about 45-50 W/m2).
        Which means that, radiationwise, the sfc in the dry areas on average heats about the same (from direct solar input), but at the same time cools a lot more (from ‘net radiative (radiant heat) loss’) than the sfc in the wet areas. And is STILL substantially warmer, on average.
        You could also look at it this way: The sfc in tropical/subtropical desert/dry areas absorbs a much smaller total mean radiative input (solar SW + atmospheric LW) (~550 W/m2) than what the sfc in tropical/subtropical rainforest/wet areas does (~580 W/m2). (That’s about 30 extra W/m2 of radiative input.) While at the same time radiating out (UWLWIR) about 10-20 W/m2 more on average.
        So why aren’t the latter areas (the ‘wet’ ones) warmer on average? Why are the former areas (the ‘dry’ ones) warmer?
        What is even more interesting is that the discrepancy is even larger at the ToA above the same areas. At the ToA level, the rainforest/wet areas absorb a lot more solar radiation on average than do the desert/dry areas. This evens out upon reaching the surface, which means that something happens in between those two levels. The larger amounts of water vapour and clouds in the ‘wet’ atmosphere simply absorb a lot more of the incoming solar radiation than the mostly water-depleted air in the ‘dry’ atmosphere, preventing it from ever reaching the surface as ‘radiant heat’.
        The atmosphere thus lets a lot more solar (SW) heat IN through the ToA (albedo included) above the tropical/subtropical rainforest/wet areas than above the tropical/subtropical desert/dry areas, while letting a lot less terrestrial (LW) heat OUT to space through the ToA.
        This is simply how the atmospheric ‘greenhouse effect’ is defined. According to this definition, it is much stronger above the rainforest/wet areas than above the desert/dry areas.
        And STILL the sfc temp in the latter areas is significantly higher on average. Completely at odds with (in fact, opposite to) what theory tells us. A stronger ‘atmospheric radiative greenhouse effect’ SHOULD lead to a warmer sfc … ON AVERAGE.
        So why doesn’t it? And where is the empirical evidence from the Earth system that it still does somehow?
        Does radiative balance determine sfc temp at all? Or are other processes governing it?
        https://okulaer.wordpress.com/2014/11/16/the-greenhouse-effect-that-wasnt-part-2/

        • Kristian,
          I provided the answer downthread:
          Those dry desert regions that become hottest under insolation despite having least DLR from GHGs and then radiate most to space when insolation stops.
          So it isn’t DLR from GHGs that makes those desert surfaces hotter than S-B and there is little DLR from GHGs at night to reduce outward radiation to space.
          What makes those surfaces with least DLR the hottest relative to S-B during the day is adiabatic warming of descending air and at night the absence of DLR allows rapid surface cooling such that inversions occur with the ground becoming colder than the descending air above.
          Those dry areas with most DLR getting to space directly from the surface are beneath columns of adiabatically warming descending air within semi-permanent high pressure cells.
          That perfectly illustrates my contentions that:
          i) The ‘extra’ warmth at the surface (above S-B) is caused not by downward radiation but the reconversion of PE to KE as descending air compresses beneath the increasing weight of the atmosphere above as it descends. If that extra surface warmth were caused by downward radiation from GHGs then the colours would be reversed and the warmest surfaces would be beneath the more humid regions (more GHGs).
          ii) The kinetic energy available to be extracted at the surface from descending adiabatically warming air is more readily lost directly to space from those desert surfaces due to the lack of GHGs above (dry air) and so as per my previous comments here and elsewhere it is the adiabatic convective overturning cycle that varies so as to readjust the energy escaping to space directly from the surface as compared to that escaping to space from within the atmosphere.
          Willis has kindly proved my case with this article and for readers who still don’t understand what I am saying I can only recommend some meteorology studies.
          The truth is that GHGs merely reapportion radiation escaping to space between that leaving from the surface and that leaving from within the atmosphere and the mechanism effecting that reapportionment is the adiabatic convective overturning cycle. Both before and after any such reapportionment radiation out to space matches radiation in from space and surface temperatures remain the same despite small variations about the long term average which is set by atmospheric mass and density.
          GHGs thus have zero effect on surface temperatures but would have a miniscule effect on atmospheric circulation and the positioning of the climate zones but any such effect is magnitudes smaller than similar effects from solar and oceanic variations

      • Kristian said:
        “the sfc in the dry areas on average heats about the same (from direct solar input),”
        No it does not, the surface in drier regions get heated more as there is less atmospheric water vapour present to absorb solar near infrared.

      • Ulric,
        You need to take into account that the desert/dry areas in general lie further from the equator than the rainforest/wet areas, so that the annual mean solar input through the ToA is substantially larger over the latter ones than over the former ones. This equatorial surplus at the ToA, however, is equalized at the surface because of the larger atmospheric absorption (which you correctly point out). Furthermore, the desert surface albedo is much higher than the rainforest surface albedo, offsetting quite a bit of the higher cloud albedo of the rainforest atmosphere.
        I am not just throwing out assertions here, Ulric. I base my arguments on the CERES dataset.

      • Stephen,
        You know how I feel about your absurd ‘descending adiabatic heat’ hypothesis. It is just so fundamentally wrong and stupid. So why bother telling me about it even one more time?
        I’ve decided to leave you and your ramblings alone (at long last). (Any counter-argument to your self-invented concoctions rolls off like water off a duck’s back anyway.)
        Now please grant me the same favour …

        • Kristian
          I know that you think an adiabatic process involves a transfer of heat (as work) between a rising or falling parcel of air and the air in its surroundings.
          That is incorrect and if it were correct it would be a diabatic rather than adiabatic process.
          The adiabatic process involves work done with or against gravity and not work done against surrounding molecules and so no heat transfers in or out whether via work done or otherwise.
          It takes work to lift the mass of a molecule up against the force of gravity and that work converts KE (heat) to PE (not heat) which is then recovered on any subsequent descent.
          Roy Spencer referred to descending air warming by subsidence so you have more than me arguing against you. You should also look up Foehn winds and similar phenomena.
          I will draw attention to your error for so long as you continue to get it wrong.
          If you would just correct that error then the rest of your points fall into place (I agree with most of your narrative but for that error) and you will understand why deserts with few GHGs above them get warmer than humid regions with lots of GHGs above them. As you point out, that is exactly the opposite of AGW theory 🙂

      • Kristian said:
        “This equatorial surplus at the ToA, however, is equalized at the surface because of the larger atmospheric absorption..”
        With the amount of cloud albedo on the equatorial belt, it probably does more than equalize. And don’t forget, there are two horse latitudes, and only one equator.

    • Actually, the interesting part isn’t just what you observed.
      Besides the absolute temperatures, one other feature which deserts differ from other land regions is also the relative, if not absolute, lack of vegetation. Semi-facetiously, maybe the reason deserts are so hot is because there aren’t many plants to absorb the solar radiation and to more slowly re-radiate it back because the plants themselves – via their direct consumption of solar energy and the large role of water in the plant life cycle (stomata operation) – affect the energy flow and regulate the water vapor levels.
      It would be ironic if global temperatures are actually a function of net plant biomass behavior.

      • Actually I think vegetation just creates a air gap insulation over the surface, since the ground has a very high heat capacity compared to the atm.

      • The only reason there are plants there at all is because they absorb the energy and turn it into plants. Plants are endothermic. They also shade the ground by day and insulate it by night.
        I like plants. May all deserts be covered with them.

      • I think main reason why wet equatorial areas are colder than dry desert areas near equator is photosynthesis. As it is endothermic reaction it is removing heat from air and storing it in chemical energy. It looks like photosynthesis efficiency is around 0.1% – 6%. Where typical plants have 0.1% – 2%. Taking average temperature 298K and 2% it means around 6K of removed heat. But plants are only working during day not night, so divide it roughly by 2 and here we are 3K difference why it is colder in wet areas than in dry areas.

    • Another reason why deserts can get hot during the day is lack of trees. Here in New England, trees evaporate a tremendous amount of water, and that soaks up a huge amount of heat. In fact, the ground here is pretty much saturated from winter to leaf-out. The decline in river runoff when leaves finally come out is striking.
      Some desert surfaces have very poor heat conduction, these, especially those at high altitude are notorious for getting cold as soon as the sun goes down and hot when it comes back up. Other areas, like valleys cut through basalt soak up heat all day long and radiate it back to people who thought it would be nice to camp by the river.

  3. Excellent find Willis. What does this tell us about model feedbacks?
    If this Brunt method is what is used in climate models, it will mean that water vapour feedbacks are out by factor of two in one direction or the other.
    Don’t have time to think it through right now, so I’ll just throw it out.

    • Thanks, Mike. The Brunt method is not used by the climate models as far as I know.
      w.

      • My last home had radiant ceiling heat. People questioned it’s efficiency because as everyone knows “heat rises.”
        I only questioned the operating cost of operating electric blankets installed between the joists. The original owners intended to install a small wind turbine on the property but never got around to it or came to their senses.

      • Mike says: March 28, 2015 at 1:57 am

        BTW radiation does not “well up” or “well down” it radiates. 😉

        Ahh, you’re one of those folks who expects English to be logical …
        This is what is called a “term of art”, which is a word that used in an unusual manner in a particular profession or trade. If you do a search in climate works for DLR or “downwelling radiation”, you’ll find thousands of examples.
        It is used to distinguish between upward-directed radiation that is headed for space, and downward-directed radiation that is headed for the Earth. It’s clear and unambiguous and has been in use with these meanings for years, so I fear you are stuck with it.
        My best to you,
        w.

      • Thanks for your cordial reply Willis.
        I do not expect the english language to be logical but I do expect it of science and scientific language.
        Yes we probably are stuck with it, like we’re stuck with trying to understand a highly complex chaotic system with “linear trends”, like we’re stuck with constant rigging of datasets and were stuck with everything in life being caused by CO2 emissions.
        Like we’re stuck with temperature “anomalies” which prejudge any change as being abnormal.
        You will also find thousands of references to “downwelling Kelvin waves” which is an oxymoron: Kelvin waves are a surface or boundary phenomenon and as soon at it’s downwelling it’s not a Kelven wave.
        Climatology is full of this junk and for the most part is junk science which is why I call it out.

  4. It is not too surprising that this gives a map of water vapour, since it is known that water vapour accounts for about 80% of the total GH effect.
    Brunt apparently under-estimates the downward LW over tropical ocean. presumably these a1, a2 values were established way back, a2 would seem to be what could be regarded as the water vapour feedback, meaning it is probably under-estimating WV feedbacks in models.
    But the tropics are not warming dramatically, in fact they are dramatically stable. So some other feedback must be compsensating.
    The most obvious solution is tropical cloud cover cutting down incoming solar, rendering the tropics highly insensitive to downward longwave radiation.
    You will not be surprised by that 😉

    • Shouldn’t the tropics remain stable since water vapor was already fairly close to a saturation point. Any percentage change would be minimal. My understanding is that the cold dry air of the polar regions is where the amplification would be expected to be most enhanced. But, Antarctic isn’t cooperating.
      Just a question.

  5. ” I used the “Brunt” method, which calculates an “effective emissivity” from the vapor pressure. The vapor pressure in turn is calculated from the surface temperature. I subtracted the satellite observations from the Brunt estimate. Figure 1 shows the result.”
    As you say the vapor pressure of water cannot be calculated from the surface temperature. Therefore the Brunt method is wrong. It would be interesting to see the map of the Ceres data alone.

    • Paul Berberich March 28, 2015 at 1:58 am

      As you say the vapor pressure of water cannot be calculated from the surface temperature.

      I don’t recall ever saying that. Please provide the quote where I made that claim.
      Thanks,
      w.

      • “This is the first time I’ve looked at the difference between a variable in the CERES dataset and an estimate of that variable. They say that all models are wrong, but some are useful. This model of downwelling longwave radiation is obviously wrong … but it’s useful because of exactly where and how much it is wrong.”
        Sorry, I interpreted your words that the vapor pressure of water can only be calculated from the surface temperature, if you assume 100 % humidity.

  6. Willis,

    I busted out laughing when I saw that graphic come up on the silver screen.

    Try as I might, I’m not getting the joke. But then I don’t know which Ceres product you’re using, nor what data you used for the Brunt calculations.

    • the method Willis used assumes water vapor is proportional to surface temperature, but it doesn’t account for the nature of the surface (whether it has water to evorate), thus the mistie between the satellite measurement and theory provides a perfect means to identify dry regions. Brunt is a pretty decent overall method if the mistie is a 0.6 watts per m2 underestimate versus the satellite measurement.
      When I saw it I laughed even harder because I realized the Eocene thermal maximum was caused by the shallow oceans that covered areas such as Central Asia and parts of Siberia (and if anybody wants to write a paper about it don’t forget where you got the idea).

      • Fernando Leanme,

        the method Willis used assumes water vapor is proportional to surface temperature …

        Mmm, that’s not what I’m reading. I used the “Brunt” method, which calculates an “effective emissivity” from the vapor pressure.
        Where is the vapor pressure data from? Stokes has dug deeper into it than I have: http://wattsupwiththat.com/2015/03/28/the-desert-finder/#comment-1893207

        … but it doesn’t account for the nature of the surface (whether it has water to evorate), thus the mistie between the satellite measurement and theory provides a perfect means to identify dry regions. Brunt is a pretty decent overall method if the mistie is a 0.6 watts per m2 underestimate versus the satellite measurement.

        It’s not at all clear to me that such a method is “perfect”. That’s why I don’t understand joke … it looks to be based on flimsy premises. As well, he’s being ambiguous about which Ceres data product he used: I used surface downwelling clear-sky longwave.
        That parameter is available in both the SYN1deg and EBAF-Surface products: http://ceres.larc.nasa.gov/order_data.php
        They are NOT the same. A thorough analysis would compare the differences between those two products as well. A seriously thorough analyst might not find anything worth joking about. With Willis, we’ll likely never know.

      • Brandon Gates March 29, 2015 at 7:32 pm

        Fernando Leanme,

        the method Willis used assumes water vapor is proportional to surface temperature …

        Mmm, that’s not what I’m reading.

        I used the “Brunt” method, which calculates an “effective emissivity” from the vapor pressure.

        Where is the vapor pressure data from? Stokes has dug deeper into it than I have: http://wattsupwiththat.com/2015/03/28/the-desert-finder/#comment-1893207

        … but it doesn’t account for the nature of the surface (whether it has water to evorate), thus the mistie between the satellite measurement and theory provides a perfect means to identify dry regions. Brunt is a pretty decent overall method if the mistie is a 0.6 watts per m2 underestimate versus the satellite measurement.

        It’s not at all clear to me that such a method is “perfect”. That’s why I don’t understand joke … it looks to be based on flimsy premises.

        Thanks, Brandon. The joke was that when I did the analysis I wasn’t expecting a desert finder, or that it would be so amazingly accurate.
        As Nick Stokes noted, because I don’t have any gridded global humidity data, I just used the vapor pressure for water at the surface temperature. This seems to be quite accurate where there is surface water, and the deviations from accuracy occur in the dry areas and the very humid areas.
        As to whether it’s based on “flimsy premises”, it delineates the deserts better than any other satellite data I know of, and it does so using a dataset with no humidity measurements at all. I find that both surprising and funny, but not “flimsy”.

        As well, he’s being ambiguous about which Ceres data product he used:

        I used surface downwelling clear-sky longwave.

        That parameter is available in both the SYN1deg and EBAF-Surface products: http://ceres.larc.nasa.gov/order_data.php
        They are NOT the same.

        I apologize for the ambiguity. I thought I was being clear. I’ve never used or discussed anything but the EBAF CERES dataset, so I didn’t think to identify it as the EBAF dataset.

        A thorough analysis would compare the differences between those two products as well. A seriously thorough analyst might not find anything worth joking about. With Willis, we’ll likely never know.

        I fear I don’t see that a comparison of the two products would show anything of value. If you think there is something there, the data and I await your serious and thorough analysis. Me, I tend to dig where I think there might be gold.
        My best to you,
        w.

    • OTOH, I looked at the image before reading much more than the title and wondered why Willis included an image of desert and moist areas. I hate humidity, I’m not going to visit the Amazon!

  7. You did not mention the timescale of the CERES data. Looking at the link that you provided in an earlier article (Feb15th 2015) the latest set is for mid 2014 it seems to me . But some of the datasets go back 15 years , so could your latest technique be applied to see if there is a change in the “greening ” of desert areas over the last decade or so ?.

  8. Willis,
    It’s not clear to me what data you used for the vapor pressure e in the Brunt expression. According to your linked paper, e is not the saturated vapor pressure, but has to be multiplied by the locally measured relative humidity, which of course would be low in desert regions. Did you do that?

    • Nick, according to the linked paper,

      Brunt’s (1932) equation estimated longwave atmospheric irradiance from screen-level temperature and water vapor pressure …

      I don’t see anything in there about relative humidity … what am I missing.
      w.

    • “My first guess would be that they assumed saturation, i.e., 100% relative humidity.”,
      Well, the linked paper didn’t:
      “relative humidity and air temperature were measured by means of an HMP35AC solid-state probe (Campbell Scientific, Inc.)”
      But Willis seems to have. I think that is why the deserts show out as discrepancies.

  9. An interesting read as usual, thanks. Here is my limited take on the subject.
    If ‘greenhouse gases’ are absorbing energy from the sun then that ‘absorbed’ energy never reached the surface. Seems reasonable the absorbed energy warmed the atmosphere but THAT energy is no longer available to be included in the DLR. As I understand it, only half the energy emitted by ‘greenhouse gas molecules’ in the atmosphere can reach the surface. I have read reports that less than half reaches the surface depending on the altitude of the gas. This all looks to me like a day time cooling effect.
    Clouds have a marked effect on local temperature.
    Many times I have noted, after a warm clear sunny day, the early night time temperature drops sharply. If a bank of cloud moves in during the night the temperature rises. This rise in temperature can approach the daytime temperature but I have not seen it exceed the day time temperature. This looks to me as a clear example of ‘back radiation’ from the cloud base reducing the radiation cooling of the surface which allows heat stored during the day to reach the surface and the night time temperature to rise.

    • “This all looks to me like a day time cooling effect.”
      Way back when I started questioning “Co2 drives the climate” thing, I compared average highs and lows between Shreveport, LA and Yuma, AZ and came to the same conclusion. During the day time our atmosphere act like a swamp cooler. On average Shreveport was 15 degrees cooler than Yuma. At night there wasn’t more 5 degrees difference in lows, Yuma being warmer. That’s when I knew that “CO2 drives the climate” was nothing more than a political driven agenda.

      • old construction worker
        March 28, 2015 at 3:57 am
        That’s when I knew that “CO2 drives the climate” was nothing more than a political driven agenda.
        ——————-
        As far as I can tell there is no any such agenda there, politically or otherwise driven.
        If your refer to AGW,, again as far as I can tell, it has nothing in connection with CO2 been a climate driver. Actually in contrary, in the AGW point of view CO2 is a climate changer at the such high modern CO2 emissions in the anthropogenic era and it is an amplifier of warming as far as considered in the long past term of natural climate.
        In both these cases CO2 is not considered as a driver of climate change.
        As a driver in principle the CO2 will mean an effect that drives and assist climate change, but it does not cause it. It means that it will drive (accommodate and help towards better efficiency) the climate through its variation, through warming and cooling also, especially in the turn of the trends, at the famous points of the lags…….
        Just saying for the sake of terminology.
        From my point of view the problem is that the RF (CO2,,, Greenhouse effect) are not really considered in the angle of it been a climate driver, not seriously.
        cheers

    • Yes, the Moon demonstrates that the effect of an atmosphere is moderating: reducing the maximum temperatures and raising the minimums.

  10. At last there is proof that man’s emissions of CO₂ are affecting the global temperature. As the CO₂ level goes up, the deserts are greening and the DLR increases, sorted.

  11. What this seems to tell us is that water vapour is the overwhelming major medium of energy interchange in the climate. And yet it is completely ignored by the Alarmists….
    This is roughly akin to architects suddenly getting concerned about the buoyancy of buildings (which displace air, of course) and insisting on adding this to all weight and stress calculations which are done. Then panicking over the fact that during low-pressure episodes the building’s buoyancy could change drastically, resulting in building collapse…..
    Hey! I’ve just invented a new reason for getting grants…..

  12. I wish that Willis would use his talents to look at some of the iconic CAGW issues. Like another look at humidity, the hot spot, Mann’s HS, temp adjustments, arctic/ Antarctic ice, sea level rise, extreme weather events etc.
    How do the above compare up to 1950 and since 1950, because this is the IPCC’s date for impact from co2 emissions. Just asking. BTW I’m sure I’ve missed a number of the more cherished icons of the alarmists. How about it Willis, even one a week or so would be good?

    • Neville, I’ve looked at many of those, including Mann’s work, the “hot spot”, arctic and antarctic ice, and sea level rise.
      w.

    • Neville:
      Why don’t YOU look into it?
      Willis looks into the things that fascinate him, as it should be. Life is too short to do what other people want you to do…

  13. Some of the greatest DLR comes from areas where there are great rivers in the Northern parts of South America. One has to wonder what impact irrigation has had on the earth’s climate. Modern large scale irrigation must have produced sustained increases in DLR in (land) areas that otherwise would have freely radiated much more towards space, thus moderating temperature. Particularly at night…

    • Let’s hope that the CAGW crowd does not begin to include water vapor among their list of greenhouse gasses to regulate. I can just see them lobbying to ban all man-made forms of irrigation. After all, it would fit the left’s agenda to decrease the Earth’s population.

      • NOAA –
        I certainly hope you are not logging in with a traceable identity (like wordpress…).

    • Tim, John Christy has a good paper on the effect of irrigation on the weather around the central valley in California. Sorry, no link to hand.
      w.

      • That would be this paper…
        http://journals.ametsoc.org/doi/abs/10.1175/JCLI3627.1
        Abstract
        A procedure is described to construct time series of regional surface temperatures and is then applied to interior central California stations to test the hypothesis that century-scale trend differences between irrigated and nonirrigated regions may be identified. The procedure requires documentation of every point in time at which a discontinuity in a station record may have occurred through (a) the examination of metadata forms (e.g., station moves) and (b) simple statistical tests. From this “homogeneous segments” of temperature records for each station are defined. Biases are determined for each segment relative to all others through a method employing mathematical graph theory. The debiased segments are then merged, forming a complete regional time series. Time series of daily maximum and minimum temperatures for stations in the irrigated San Joaquin Valley (Valley) and nearby nonirrigated Sierra Nevada (Sierra) were generated for 1910–2003. Results show that twentieth-century Valley minimum temperatures are warming at a highly significant rate in all seasons, being greatest in summer and fall (> +0.25°C decade−1). The Valley trend of annual mean temperatures is +0.07° ± 0.07°C decade−1. Sierra summer and fall minimum temperatures appear to be cooling, but at a less significant rate, while the trend of annual mean Sierra temperatures is an unremarkable −0.02° ± 0.10°C decade−1. A working hypothesis is that the relative positive trends in Valley minus Sierra minima (>0.4°C decade−1 for summer and fall) are related to the altered surface environment brought about by the growth of irrigated agriculture, essentially changing a high-albedo desert into a darker, moister, vegetated plain.
        And their hypothesis appears to be that all of the warming in the region can be attributed to irrigation (and other land based changes) but it seems to me that there are far too many assumptions to be of any real use in that regard.

      • This theory appears to be not correct — look at any standard meteorological text books Also, sea breeze, land breeze theories, etc. Irrigated zone should follow cold-island effect and non-irrigated zone should follow heat-island effect.
        Dr. S. Jeevananda Reddy

      • If someone in northern BC or AB wants a research project on water affecting local climate, there’s the very large lake created behind a power dam on the Peace River, circa 1960s. http://en.wikipedia.org/wiki/Williston_Lake
        I expect that storage increased evaporation there, whereas normally the water would have flowed into northern AB then on to the Arctic Ocean, perhaps with more evaporation along the way due to higher water levels in lakes but less overall (presuming less in the Arctic as it is colder). I presume there’d be more water flow in winter due to release from the dam for power generation.
        Locals claim the climate is wetter there now, and that growing hay for seed has replaced grain crops.
        However, that could be due in part to climate variation and to more clever farming.
        (Growing what works better more often. Wheat can be chancy there due risk of early snow before harvested, IIRC barley and oats were grown often but dry years were a problem. Choice of crops even depends on how many animals are raised – I have names of cattle farmers downwind of the lake, they probably know some in the Chetwynd area which is south of the lake.

  14. I presented a series of equations to estimate precipitable water, global solar and net radiation in 70s-80s:
    Rt [global solar radiation] = a x L x [square root of saturated water vapour];
    Rt = a + b x [la] + c [cube root of precipitation in mm]
    Rn [net radiation] = b x L x [wet bulb temperature in degrees Celsius];
    W [precipitable water vapour, gm/square cm] = c [square of Wet bulb temperature in degrees Celsius];
    Dr. S. Jeevananda Reddy

  15. I think it needs to be remembered that evaporating each Kg of Water absorbs 2.2 KJ of heat which it also radiates to space. High levels of evaporation extracts heat energy from the surface which is why oceanic regions are so much cooler than deserts, so while DLR may be larger, the Nett effect is to cool during the day, and heat at night. That is water vapour moderates extremes.

    • At night you can see rel humidity increase as it cools, at higher values water starts to condense out, tte heat that water has to give up, slows cooling, but it also drys the air. In the morning any water not lost the environment evaporates back out as it warms. But this process regulates both temps and humidity.

      • Up a ways you asked about how air gives up heat when it cannot emit infrared. Gases such as nitrogen give up energy by physical contact to molecules of carbon dioxide, methane or water which CAN then emit infrared. In this sense, more carbon dioxide improves “top of atmosphere” cooling by becoming a more effective radiator, but it also retains more heat at the surface. This increases the vertical gradient which in turn would usually provoke more convection.

    • “…water vapour moderates extremes [in temperatures].”
      Yes – consider the moon: -233 C to +123 C

  16. My quick estimate for the world’s tallest building suggests that its buoyancy in air is about 2,000 tons. That surprised me – I would have thought it was less. It’s still around 0.00001 of total weight, so the comparison with CO2 concern still stands…

    • This is just the measurements or the estimates. The equatorial areas will give off more as they receive the most direct sun every day. Willis subtracted the measurements from the estimates to gauge accuracy of said estimates. The estimates are way too high for the arid areas in the desert belts. They are also too low for the tropics. — John M Reynolds

    • lgl
      Those charts show that most DLR is directed downward in the more humid regions.
      That is consistent with Willis’s chart that shows least DLR in the dry desert regions.
      Yet it is those dry desert regions that become hottest under insolation and then radiate most to space when insolation stops.
      So it isn’t DLR that makes those desert surfaces hotter than S-B and there is little DLR at night to reduce outward radiation to space.
      What makes those surfaces with least DLR the hottest relative to S-B during the day is adiabatic warming of descending air and at night the absence of DLR allows rapid surface cooling such that inversions occur with the ground becoming colder than the descending air above.

        • lgl,
          Why do locations receiving 2 thirds of their energy as DLR get hotter than locations receiving more of their energy as DLR?
          Where do you think that DLR in regions with few GHGs comes from ?
          I say it comes from the adiabatically warmed molecules closest to the surface and not from GHGs at all.

        • lgl commented

          2/3 of the energy to the surface in ‘dry’ places is DLR

          This energy is stored in the ground, not the air. It’d be nice to see the rest of the data for these measurements, like what was the humidity, even low rel humidity could have a lot of water, and the ground is going to be radiating which water and Co2 will return, but the amount of SW going up and the amount due to water are critical to understanding.
          I think many people don’t distinguish these parameters, because when you say the total average of 3.2W/m2 is tiny compared to the other parameters, plus we don’t know that it’s wholly contained by the energy bounds of atm water (as the station graph I posted shows actually happens).

      • Stephen
        Almost all DLR comes from GHGs (and clouds, but there are none in the plot from Nevada).
        There is almost no DLR coming from your adiabatically warmed N2 and O2 molecules.
        The only regions with “few GHGs” are the polar regions, where there is also little DLR.
        There is more vapor above the Sahara and Australia than above Europe and the US for instance

        • lgl
          You accept that there is little in the way of GHGs above deserts.
          Yet deserts reach temperatures higher above S-B than do humid areas with more GHGs.
          Why do you think that happens ?
          It can only be because of adiabatically warmed descending air.
          Hence it is that descending air that causes the ‘extra’ 33C at the Earth’s surface and not downward radiation from GHGs.

        • I should add that the ‘extra’ warmth at the surface of deserts is achieved via sunlight PLUS restraint of convection by the descending air column and not by the DLR that is received.
          If DLR had a warming effect then one would see higher surface temperatures above humid regions than above dry regions.

      • Stephen
        Perhaps you should look up adiabatic, “taking place without loss or gain of heat”. An adiabatic process can’t heat the surface, DLR can.

        • lgl
          “An adiabatic process is one that occurs without transfer of heat or matter between a system and its surroundings”
          http://en.wikipedia.org/wiki/Adiabatic_process
          I have come across various misunderstandings of adiabatic processes and yours is one of them.
          During uplift and descent no transfer of heat occurs between the rising and fgalling parcel of air and the surrounding air.
          Instead, energy within the parcel is transformed from KE (heat) to PE (not heat) during uplift and the reverse on the descent.

      • Stephen
        Exactly, “within the parcel”. So you agree the adiabatic warming does not warm the surface then?

        • Adiabatic warming of descending air warms the surface indirectly in two ways:
          i) Clouds dissipate so more sunshine hits the surface. Similarly a glass greenhouse roof being transparent allows sunshine in.
          ii) The descending air inhibits convection from the surface so that surface temperature can then rise above S-B. Similarly a glass greenhouse roof inhibits convection.
          The greenhouse effect is aptly named but it is a product of atmospheric mass and not radiation.

      • Stephen
        “inhibits convection”?
        Air is descending because air is ascending at another place. This process does not add any energy to the surface, and it is the energy balance at the surface that sets the temperature. And I have shown there is a lot of DLR at night, so still all wrong.

        • lgl
          There is less convection beneath a high pressure cell (which is by definition a column of descending air warming adiabatically) than there is beneath a low pressure cell.
          The overall radiative energy balance is maintained by the interaction between adiabatic uplift and adiabatic descent.
          If there are no radiative gases all incoming energy from the sun departs back to space from the surface and in that situation energy taken up in uplift matches energy returned towards the surface in descent.
          If one adds radiative gases then radiation to space from within the atmosphere then becomes possible and energy returned towards the surface in descent falls short of energy taken up in ascent.
          That reduction in energy returning to the surface offsets what would otherwise have been a surface warming effect from the radiative gases.
          Surface temperature stays the same but the air circulation changes instead with more energy leaving to space from within the atmosphere, less leaving from the surface direct to space and the radiative balance maintained overall.

      • Stephen,
        wrong wrong wrong. Adiabatic means there is no energy “taken up in uplift” or “energy returning to the surface”. The only ‘uplifted’ energy is latent heat, and some of that is lost to space and some is returned to the surface as DLR.

        • lgl
          The term adiabatic is limited to ascent or descent after initial lift off or before the lowest point of the descent.
          The initial lift off is caused by diabatic solar heating of the surface. Only after that initial event does the continuing ascent become adiabatic.
          When the warmed air descends to its lowest point (which need not be the surface if an inversion is present) then it indirectly causes enhanced diabatic heating of the surface by dissipating clouds and inhibiting convection.
          The term latent heat is limited to the (non thermal) energy carried by the vapour form of water.
          That term does not cover the transformation of KE to PE or PE to KE when work is done against or with gravity in the adiabatic process.
          You have some serious thinking to do if you are to overcome the conceptual flaws in your understanding.

      • Stephen
        Serious thinking probably won’y help in your case. You will have to learn some physics.

      • lgl
        If the N and O2 heat the CO2 via molecular vibrations, will the CO2 then have the ability to issue a photon as long wave radiation? If so, then SWs explanation holds true imo.

      • Adiabatic means there is no energy “taken up in uplift” or “energy returning to the surface”.

        lgl, SW gave you the correct definition of “Adiabatic”, so I won’t repeat it. Your statement here indicates that you don’t understand how physical transport affects heat transfer. For example, rain falling is physically transferring heat away from the surface as energy is transferred from warm surface to cold water. Similarly, warm air rising is physically transferring energy away from the surface without involving radiation or conduction. Cooler air is pulled in from the side, which is then warmed and rises.
        The air closest to the surface is typically in near thermal equilibrium with the surface. The surface is heated by solar radiation, and the surface temperature rise is not just limited by the air, but by the thermal conductivity and heat capacity of the land or water. As the surface temperature rises, the low heat capacity air (right above the surface) follows in lock step.
        This triggers a delta T between this air and air higher up. Lower air heats higher air, but is then immediately heated by the surface, as soon as any delta T opens up between the surface and the lowest air. When one places one’s hand on a large marble structure, the difference in heat capacity means that our hand cools quickly, while the marble structure temperature drops infinitesimally. Similarly, the hot surface can easily keep the air in near thermal equilibrium.
        When solar radiation stops, heat is drained from the surface in multiple ways. An important (but often forgotten) way is that heat is conducted away by land and/or sea. Even if there was no other way for the surface to lose energy, this alone would result in a cooling atmosphere, as the air temperature near the surface would still stay in lock step with the cooling surface. Of course, energy is also drained into the rapidly cooling atmosphere.
        I believe that SW’s point was that over a desert, with a parked high pressure zone, no rain, air rising slows, convection is diminished, the surface will heat up more, limited only by thermal conductivity of the surface. Sounds reasonable.
        Convection is radiation/conduction over and over again. That’s why convection dominates in the Troposphere. An atmosphere of only N2 and O2 would be a poor conductor of heat. Adding water vapor and C02 increases thermal conductivity, transferring heat from the surface easier. It’s unreasonable to think that this would result in a higher surface temperature.
        I think Clive Best explains it well:

        So to discuss the “greenhouse effect” in isolation from convection and evaporation is wrong and so is discussing thermodynamic effects without including radiation. http://clivebest.com/blog/?p=4432

  17. I wonder how did the map look like after you used your fitted values. I guess it wasn’t map of water vapor anymore.

  18. A couple observations, it says a lot about GH effect because you can see that it’s water vapor that regulates nightly cooling, as it cools, rel humidity goes up and cooling slows down above~80%, this shows that effect, but I’m suspect on the polar areas, downwelling IR has to be mostly from surface temps, and at- 40F, there isn’t a lot of upwelling IR to be reflected back.

  19. I too am interested in the dataset you used. It seems to me that the poles should show up as more arid. I wonder if the long dark polar winters and midnight sun summers affect the data. Is an annual average or just several days near June 21 like in the paper you linked? — John M Reynolds

    • Note that the error is given as total DLR, not a percentage. The low temperatures at the poles means that DLR is quite lows there. Even so much of East Antarctica is “borderline desert”. It would be very interesting to see a map that shows percentage discrepancies rather than absolute figures.

  20. “This one was funny to me because it was such an excellent and detailed map of the desert and arid areas of the planet.”
    The yellow regions look more extensive than the actual desert regions. Reduced atmospheric water vapour in the horse latitudes is not solely dependent on dry land regions.

  21. Using surface temperature to estimate absolute humidity of the atmosphere is just an approximation, and will of course be too humid in desert regions and too dry in the ITCZ, Amazonia, and the Congo basin. An interesting factoid about major deserts is that they are net radiative sinks, that is, they absorb less radiation from the sun than they lose to space in the infrared. They are part of the Earth’s radiative exhaust ports.

    • I don’t know if Kirchoff would agree with you. His stuff is a law and not a theory. High absorber , high emitter. Low absorber, low emitter. Based on wavelengths, of course. Broad spectrum readings and albedo are a bunch of crock. All the SB , planck theories were based on individual wavelengths or narrow bands of wavelengths. The earth is not a blackbody. It is covered in regions of non grey bodies.
      If you choose to , you can turn your head to the side and squint your eyes and pretend the average of earth is a sort of grey body.
      I hope I misunderstood your comment.

      • apparently you did misunderstand. The deserts absorb an average amount of sunlight, and (along with the overlying atmosphere) give off an average amount of IR to space. The latter is somewhat larger than the former. The difference is made up by atmospheric energy transport from other regions, which warms the desert airmass from subsidence-induced heating, driven by latent heat release in rain systems elsewhere. Not a controversial subject that I know of.

        • Roy Spencer said:
          “The deserts absorb an average amount of sunlight, and (along with the overlying atmosphere) give off an average amount of IR to space. The latter is somewhat larger than the former. The difference is made up by atmospheric energy transport from other regions, which warms the desert airmass from subsidence-induced heating, driven by latent heat release in rain systems elsewhere. Not a controversial subject that I know of.”
          SUBSIDENCE INDUCED HEATING
          That is what makes the desert surfaces rise above the S-B temperature and NOT DLR which is why the deserts get hottest when they have least DLR.
          The only point I disagree with Roy about is that he thinks that a non GHG atmosphere would become isothermal but it would not because uneven surface heating still causes density differentials in the horizontal plane so we would still see a similar air circulation pattern even if there were no GHGs at all.
          Convective overturning warms the surface above S-B via adiabatic cooling on ascent and adiabatic warming on the descent and the radiation fluxes within the atmosphere are a consequence rather than a cause.

      • Alex, I do believe you have that backwards. Planck and S-B are based on broadband radiation following the curve that Planck figured out from Kirchoff’s work on black bodies and the relationship between wavelength and temperature… what we call a black body curve. (The good absorber, good emitter thing was already known, Kirchoff built on that and Stewart’s work.) Line emitters and absorbers do NOT follow those rules and therefore have extremely small emissivity numbers (CO2’s is 0.0017 at NTP.) That’s one of the larger failings of the AGW crowd is they treat line emitters as black bodies. Emissivity varies by material so deserts of soil or sand are going to have emissivities between 0.38 and 0.76 based on the materials they contain.

      • nielszoo March 28, 2015 at 7:14 am
        I beg to differ. They use lambda in their equations. Cant type Lambda figure , but you know what I mean. They always included lambda.

      • Roy Spencer March 28, 2015 at 6:57 am
        ‘they are net radiative sinks’
        your following sentence :
        ‘they absorb less radiation from the sun than they lose to space in the infrared’
        I saw this as a contradiction.
        I wasn’t contradicting the obvious situation of airflow from other regions.

      • nielszoo March 28, 2015 at 7:14 am
        ‘Line emitters and absorbers do NOT follow those rules and therefore have extremely small emissivity numbers (CO2’s is 0.0017 at NTP’.
        A total contradiction within one sentence.
        Kirchoff’s LAW has not been found wrong. That’s why its a LAW in physics. You don’t get to be a law if there is reasonable doubt like a theory.
        Please point out to me where I can find information to corroborate the first part of your sentence.

      • jorgekafkazar March 28, 2015 at 1:16 pm
        I am not arguing with Dr Roy. Just seeking clarification. I think I was quite polite.

    • Roy Spencer said:
      “An interesting factoid about major deserts is that they are net radiative sinks, that is, they absorb less radiation from the sun than they lose to space in the infrared. They are part of the Earth’s radiative exhaust ports.”
      But the horse latitudes have less atmospheric water vapour, so they don’t absorb so much solar near infra-red, so regionally there would be higher than average surface irradiance. That’s why the deserts are there in the first place. I assumed you meant average solar radiation?

    • –An interesting factoid about major deserts is that they are net radiative sinks, that is, they absorb less radiation from the sun than they lose to space in the infrared. They are part of the Earth’s radiative exhaust ports.–
      It is kind of interesting.
      Are they exhaust ports? Or places where warmed air is expelled. Or a idea like a heat sink does not really work, not even radiate fins.
      Anyhow opposite of exhaust ports are inlet ports, and that doesn’t help much other than bring to mind, tornadoes.
      One could say deserts are the furthest extreme of a water world- or bodies of water are a contrast to deserts. And oceans seem more like heat sinks- at least in terms radiant energy from the Sun.
      Generally I would tend to think of the poles as exhaust ports though inverted exhaust ports or inlets could be as descriptive. And poles get the spinning or vortex stuff.
      Now are deserts air pumps/air fans? Do they blow in daylight and suck at night?
      Anyways deserts are most like a world which didn’t have 70% of it’s surface being water.
      It’s my general assumption that if add water to deserts one increase global temperature [though granted deserts are small area of the global]. Or I have long assumed that if large scale efforts were made to green the Sahara desert, the net result would be an increase in average temperature. Maybe that’s wrong. But in terms of exhaust ports how would greening of the Sahara
      desert affect the exhaust port of the Sahara desert?
      Or does it increase or decrease the exhaust of this exhaust port?

      • Deserts have the highest temperatures and the as good an optical path to space as anywhere, and since radiation is the only way off the planet they would probably have the highest W/m2 on the planet.

      • –Deserts have the highest temperatures and the as good an optical path to space as anywhere, and since radiation is the only way off the planet they would probably have the highest W/m2 on the planet.–
        Deserts close to tropics would be better places to harvest solar energy.
        One also has the “Horse latitudes or subtropical highs are subtropical latitudes between 30 and 35 degrees both north and south. This region, under a ridge of high pressure called the subtropical high, is an area which receives little precipitation and has variable winds mixed with calm.” -wiki
        And I assume one has Horse latitudes condition even in middle of an ocean.
        I also assume despite the large amount of solar energy that deserts absorb the smallest fraction of the incoming solar energy, in contrast an ocean absorbs the high fraction of the incoming solar energy.

      • “It’s my general assumption that if add water to deserts one increase global temperature..”
        It will cool the desert, so how will that increase global temperature?

      • Most continental interiors cool with increased rainfall, typically in a cold AMO mode, and during La Nina episodes.

      • —micro6500
        March 28, 2015 at 3:17 pm
        Possibly daily min temp would go up more than max temps go down, so the average would be higher.–
        Yes it mostly about raising the average min temp.
        But actually that is also true as far as theory of Earth’s Greenhouse Effect.
        Or all that the greenhouse effect can possibly do is raise the average min lowest temp. And the only way one can imagine the Earth greenhouse effect making it warmer is by increasing the min temperature so that in the morning
        of a day one starting from a warmer temperature, and thereby requiring less heating to get to highest daytime temperature. Or said differently if one has weather in summer which causes cool temperature, it generally takes a couple days to warm back up again.
        Or the greenhouse effect would need to prevent cooler nights in order to give you warmer days.
        But it should noted, that I don’t believe greenhouse gas are adding +33 C to Earth average temperature, so perhaps a believer in the theory would like to correct me, as far as the correct interpretation of their faith.
        And far as know the only thing which could raise max air temperature [other than starting with a warmer min temperature] would be wind blowing across a heated ground surface bring warming air to another area. Or UHI effect or lower elevation.
        Now I wondering whether anyone found that golf course should add to UHI effect [in terms of increasing night time lows] but a quick search didn’t find this, instead this article said golf courses [regions of greenery] lower UHI effects:
        http://transitiontownpayson.net/2014/04/06/adaptation-volume-10-battling-the-urban-heat-island-effect/
        And tend to agree that a park will not warm as much as asphalt parking lot.
        But also a sandy desert is somewhat like a asphalt parking lot, and likewise
        if replace a desert with greenery and waterworks it should also have cooling effect, And the large area of Sahara desert might adding considerable warmth
        to a larger region. So therefore my doubt about it.
        But just the Sahara desert region itself should be warmer due to it having warmer nights.

        • I can tell you for certain that when you look at surface station data, the annual average of yesterday’ s rising temps to last night’s falling temps, if you round to 1 decimal they are both 0.0F, if you go out to 3 (?) Falling temps are slightly larger than rising temps. Now this confused me for a long time, until I realized the excess heat was coming from air heated in the tropics. ren’s water vapor map shows large amounts of water spinning out of the tropics.

    • That makes sense. Sand and rocks reflect energy as well as absorbs energy only to released that energy later . When plant life absorbs energy some of it converted and not released.

  22. Welcome back. Whether or not I always understand what you’re writing (my limitations – not yours), your writing style is always a joy to read.

  23. “SOFIA is based on a Boeing 747SP wide-body aircraft that has been modified to include a large door in the aft fuselage that can be opened in flight to allow a 2.5 meter diameter reflecting telescope access to the sky. This telescope is designed for infrared astronomy observations in the stratosphere at altitudes of about 41,000 feet (12 km). SOFIA’s flight capability allows it to rise above almost all of the water vapor in the Earth’s atmosphere, which blocks some infrared wavelengths from reaching the ground. At the aircraft’s cruising altitude, 85% of the full infrared range will be available.”

  24. The deserts occur where the dry Hadley cell downwelling touches down. Just as the tropical rain forests occur where the wet Hadley cell upwelling begins.
    You’re looking at the effects of atmospheric circulation: the water vapor distribution is a consequence of that circulation. Your satellite imagery probably doesn’t show much of the polar areas, but they are deserts, too, because of downwelling of dry air. It should show the temperate rainforest regions (US NW and BC) where there is also an upwelling of wet air.

  25. One of the methods is right (and the other is wrong) or it might be a blend of the two.
    Nevertheless, DLR is a process that underlies the very nature of global warming theory. It is one of its key foundations. If they are doing DLR wrong or the water vapor component of it wrong, then there is a big problem.

    • From what I’ve read, DLR is a theory promoted by some. It seems to be promoted by warmists because it’s convenient. DLR comes back to downwelling radiation. CO2 heating the surface etc. If you subscribe to the idea that the atmosphere heats the earth then DLR is a ‘thing’. If you don’t subscribe to that thinking, then DLR is just a distraction from the truth.

    • I think of DLR as coming from all of the air around you. DLR could be coming from water vapor or CO2 or solid surfaces which are just metres away from you. It is being emitted side-ways, up and down and all around by every excited molecule in your/or the instruments vicinity. It is the very nature of a gas and there are billions of photons of LW hitting you every second from everything. If you are in a room right now, there are billions of photons being emitted by every solid surface in that room. It still bugs me than noone will say O2 and N2 also emit blackbody radiation but that is for another thread and another day.

      • That sounds like kinetic energy rather than radiation. The photons you are referring to are incredibly low in energy. I am not denying that they are there. Most molecules lose their “absorbed’ energy by impact with other molecules. What would be left over for radiation purposes would be negligible. I suggest doing some planck calculations. You will find that the number of photons increases, the lower down the scale you go. Essentially more photons but with a subsequent lower energy per photon until you can practically walk on a sea of photons at 3 K. The energy of a visible light photon is millions time stronger than a photon emitted at 14 micron
        I agree that photons from GHG will strike the earth, But I wouldn’t write mother about it.

      • O2 and N2 do emit radiation, But only in the wavelengths that they absorb (Kirchoffs Law). They don’t emit broad spectrum.

      • I’ve been measuring Tsky with a IR thermometer, most of the winter it was below ~-60F, the really cold days and nights it was near -80F.
        But even this cold, when rel humidity gets up over 80% cooling slows down.
        And at the same time if you measure surface vegetation it’s colder than air temp, while concrete and dirt at warmer than air temps after a night of cooling at 10F.

      • micro6500 March 28, 2015 at 7:38 am
        I’m into instrumentation. Just be careful how you use this IR thermometer. You could take your eye out. Sorry, just kidding. Even though they say that they operate over a certain range , you have to be careful.
        If you buy one of those things its like signing a contract with the devil. You really have to look closely at what the specific thermometer is designed for. Using it outside that range can give you strange readings.
        Ir thermometers are designed for specific ranges. Hi temp, cryogenic or ‘General purpose’. They are purpose built for specific applications.
        Point it at the next full moon and let us know what the temperature is. Just for fun

        • Think of it as a 8-14u signal strength meter calibrated to a blackbody. So the moon will measure the same as the rest of the sky, except in the general direction of the Sun.
          But only because there isn’t a lot of 8-14u photons, which is sort of the point.
          The caveat is you have to add the Co2 flux to the BBQ flux

      • Alex,
        the number of photons is the intensity, the energy level of the photon is the frequency, so yes lower frequencies have less energy, but that does not mean there must be more of them.
        eg moonlight has few photons at visible wavelengths and sunlight has many photons at visible wavelength.
        warmer surfaces will have more IR emission than cooler surfaces.
        the lower atmosphere in general has a lot of water vapour , so yes the dominant transfer of heat is kinetic and convection until at the top of the troposphere there is so little water vapour that radiation becomes the primary form of energy transfer. to add an extra absorber in the mix means that the surface at first loses more heat to the atmosphere, but the capacity of the atmosphere has increased, so once capacity is reached (not completely), there will be a warmer atmosphere than before. the surface can no longer lose as much warmth as it did before.
        the way the ipcc presented this was that the top of the troposphere should increase in height. it means that because the surface warmed and evaporation would increase, they predicted that the water vapour levels would increase at the top of the troposphere and due to the fact that the air is very cold there (concentrations low) there should be a very visible sign of extra warming (log up there to little on the surface).
        so, what happened? it did not warm, water vapour did not increase there. this means there is NO water vapour feedback in the radiative zone, only in the lower troposphere where there is now a bit more water vapour. warmer? yes, but how much warmer?
        well the models that the ipcc use (using those same calculations that are obviously not correct) place the feedback from water vapour at a very large percentage. the last 18 years have shown that both the upper and lower troposphere have not increased in temperature, yet the specific water vapour has increased(by as small a fraction as before). this really is proof that the feedback expected from water vapour should be in the form of rain/clouds and negative in nature, not positive. and co2, well it is just being drowned out by water vapour/clouds/whatever else.

      • Why is it that we can see things if photons are criss crossing and bouncing all over the place? Is it only LWR that does this? Even then, we can see infra red images with the right optical gear. When I read a book, the light from ‘abc’ doesn’t interfere with that of ‘def’ by criss crossing or the light from distant stars.

  26. “In the desert the air is so dry that more radiation escapes to space, and less is absorbed and radiated downwards (and upwards) by the atmosphere.”
    It would seem then that the major (and perhaps only) temperature moderator/sink on Earth is water/water vapour. I understand what you are saying but is there not also an effect on temperature as a consequence of the ground being open and dry (again lack of moisture) and that sandy deserts are poor heat reservoirs? I read that sand is a good heat sink and will release heat slowly in which case why do sandy desert areas lose heat at night so rapidly? Is it really just the open dry skies allowing radiation out or is it not compounded by the fact that the surface reservoir of heat is not that much or deep? When I’m at the beach after sunset it is the sand that seems to cool off much quicker that surrounding roads and walls.

    • ” I read that sand is a good heat sink and will release heat slowly in which case why do sandy desert areas lose heat at night so rapidly?”
      Years ago I used to do some stargazing as night in the desert. The top of the sand would cool rapidly. I would dig a shallow trench in the sand to lie in. The sand a few inches down was always warmer. I’ve also noted nearby rocks splitting off a shard from the surface with a sharp crack. On checking I found that the inner volume of the rock was much warmer than the surface. The splitting off was due to shrinkage. An example of how heat is stored in the desert rocks and doesn’t take long to warm up again during the next days sunshine.

  27. Product shows the average solar radiation absorbed (W/m2) in the earth-atmosphere system. It is derived from AVHRR Channels 1 and 2. The mean is displayed on a one degree equal area map on a seasonal basis. This product is also referred to as Shortwave Absorbed Radiation (SWAR). Absorbed solar radiation is the difference between the incoming solar radiation at the top of the atmosphere and the outgoing reflected flux at the top of the atmosphere.
    Monthly Mean:
    http://www.ospo.noaa.gov/data/atmosphere/radbud/swar19_prd.gif

  28. Willis … you’ve struck a possible gold mine!!
    Given that you have a map here of water vapor and DLR, you should be able to calculate:
    1) a curve of the contribution of water vapor and CO2 [representative of all other GHGs] on DLR in a real time scenario, vs a model.
    2) an extrapolation of the true impact of CO2 on DLR in the atmosphere with water vapor set to ZERO.
    3) the real contribution of water vapor feedback in the atmosphere according to lat/long., thus putting to rest the assumptions about water vapor in the GCMs.
    DUDE … truly, you could define the Greenhouse Effect across the globe more accurrately than any model, and from that actually approach a true attribution of Natural Forcings, Anthropogenic Forcings, as well as Feedback magnitude as data sets, and compare those to the temperature trends!! You could even do this according to Lat/Long, teasing out a differential effect of the Green House Effect at different places on the earth.
    You could be on the verge of blowing the “quantification” question regarding Global Warming wide open!!
    Just Sayin’

    • BTW … just contact Anthony for name and info, so you can put my name on the paper!! 🙂

    • Am i understanding you? Willis could use satellite data somehow to see if there is a change in the daily/seasonal timing of the overturning of heat/moisture from the tropics to the desert areas? If there is a change over X years, and if follows CO2 increases, one has hard data as to the effect of the added CO2?

    • It would be a calculated proxy no matter how you use it, and have no forward predictive use in terms of future increased CO2/water vapor amplification. You would only have scenarios if I am getting this method correctly. Given natural variability, any scenario might be swamped in noise.
      However, to narrow/refine Dr. Deanster’s comment (and please Dr. Deanster tell me if I have this wrong) if the data used in this proxy exists for the past, you might also add to it by calculating the affects of just the increasing anthropogenic portion of CO2 along with the calculated proposed increase in water vapor, then by comparison with Willis’ work, would justify AGW or not. IE you would have to subtract the amount of CO2 increase that is a natural consequence of “greening” during a warming cycle, leaving only the anthropogenic portion related to fossil fuel use, in order to see whether or not anthropogenic fossil fuel CO2 emission derived water vapor increased along with DLR. Because this part is a calculation, not an observation, you would only be able to suggest the validity or not of the AGW theory. By mind experiment, the pause could very well be explained in terms of whether or not AGW was involved at all.
      I still haven’t consumed the required amount of coffee after a Friday night so I could be just confused.

      • Pamela … essentially what I’m saying is … CO2 is estimated to be a well mixed atmospheric gas, and as such, its DLR effect should be constant within a definable parameter based on long/lat data. Desert DLR should be somewhat representative of the DLR of CO2 [and other non water vapor GHGs] with minimal contribution from water vapor … while the Tropics should be representative of the DLR of CO2 and higher water vapor. … and points in between give us middle values. Given that CO2 is constant [a well mixed gas], we should be able to fit a curve to the DLR data and draw it up on a curve relative to water vapor content. Where the line crosses the Y axis, will be representative of the raw CO2 signal at ZERO water vapor. The shape of the curve will give us a picture of how water vapor contributes to DLR with rising concentrations.
        THEN … as you say … after determining the real value of DLR contribution from CO2 in the atmosphere, we can then calculate the contribution from the anthropogenic contribution. … not in terms of ppm, but in terms of DLR!
        I’m just thinking out loud here.
        I’m definitely not sold on the CAGW or even the AGW theories .. I”m not sure CO2 or the greenhouse gas has anything to do with “rising temperature trends” .. and frankly, given the testimony of Dr. Collins at the APS debate, and confirmed by the panel … there is no first principle evidence to illustrate just WHAT caused the increase in temp. As such, I don’t think anyone knows SQUAT about climate, outside of a lot of unproven theories and hypotheses…. and mathmatical equations on radiation.
        The Brunt method comes in for corrections based on surface radiation, which could very well be influenced by lots of factors, but, if I’m not mistaken, must have some impact on the DLR, as the surface radiation is the source of the LR. It seems to me Willis comparison hints at this.
        Granted, before you slap me down, know that I do NOT view Climate from any conventional perspective. What people claim is “known” is obviously not! It’s just accepted.

      • Wasn’t even considering a slap down. I think the mind experiment is very interesting. These various proxies of intrinsic energy absorption and re-radiation is fascinating and like you, I think Willis is on to something here.

  29. There seems to be an odd hemispheric bias in the data. In the northern hemisphere the yellow areas are indeed true desert, while in the southern hemisphere much of the yellow areas are “only” steppe/savannah, e. g. much of Patagonia, Eastern Namibia, Botswana, Zimbabwe and the Murray/Darling basin of Australia.
    In the northern hemisphere the match is indeed impressive, it even “catches” the small Turkana/Didi Galgala desert of NW Kenya that most people have never even heard of.

  30. It is also the case that those dry areas with most DLR getting to space directly from the surface are beneath columns of adiabatically warming descending air within semi-permanent high pressure cells.
    That perfectly illustrates my contentions that:
    i) The ‘extra’ warmth at the surface (above S-B) is caused not by downward radiation but the reconversion of PE to KE as descending air compresses beneath the increasing weight of the atmosphere above as it descends. If that extra surface warmth were caused by downward radiation from GHGs then the colours would be reversed and the warmest surfaces would be beneath the more humid regions (more GHGs).
    ii) The kinetic energy available to be extracted at the surface from descending adiabatically warming air is more readily lost directly to space from those desert surfaces due to the lack of GHGs above (dry air) and so as per my previous comments here and elsewhere it is the adiabatic convective overturning cycle that varies so as to readjust the energy escaping to space directly from the surface as compared to that escaping to space from within the atmosphere.
    Willis has kindly proved my case with this article and for readers who still don’t understand what I am saying I can only recommend some meteorology studies.
    The truth is that GHGs merely reapportion radiation escaping to space between that leaving from the surface and that leaving from within the atmosphere and the mechanism effecting that reapportionment is the adiabatic convective overturning cycle. Both before and after any such reapportionment radiation out to space matches radiation in from space and surface temperatures remain the same despite small variations about the long term average which is set by atmospheric mass and density.
    GHGs thus have zero effect on surface temperatures but would have a miniscule effect on atmospheric circulation and the positioning of the climate zones but any such effect is magnitudes smaller than similar effects from solar and oceanic variations.

    • I sympathise Stephen
      Most people don’t realise that kinetic energy transfers more than radiation. They think that radiation is all powerful (because radiation from some substances can kill you). They don’t realise we live in an ocean of radiation and we need highly specialised equipment to find it. I can find kinetic energy effects with a glass thermometer, but that’s too boring

    • this kind of argument is a huge reason why “skeptics” lack credibility. The idea that “because ACC isn’t real, the mechanisms that they use to describe it must also not be real.” This is what most people in the den**r crowd latch onto, and a good reason for ridicule.
      The greenhouse effect is well documented and well understood. Trying to redefine it as a “redistribution” of energy is absolutely false.

      • Is it because the mis-named “greenhouse” effect conjures up wrong understandings about the real “outgoing-partially-reabsorbed-then-reradiated-in-all-directions-including-down”, Earth-warming longwave infrared radiation issue? A real greenhouse warms the inside by a different process. I prefer to say it this way: The warming effect of re-radiated LWIR.

      • A real greenhouse roof allows solar radiation in through the transparent roof and subsiding warming dry air mimics that effect to dissipate clouds and allow more solar energy to reach the surface.
        A real greenhouse roofs prevents convection and subsiding warming dry air mimics that effect by preventing warmed surface air from convecting upwards as fast as it otherwise would have done.
        The so called greenhouse effect is correctly and accurately so described but it is to do with atmospheric mass and not radiation.
        The observed radiative fluxes are then a consequence of the variable vertical temperature profile along the lapse rate slope and not a cause of anything.
        There is no radiative greenhouse effect but there is a mass induced greenhouse effect.

        • +1
          This is why over a few days clear sky day time temps can change 20-30F, cause it’s not solar or Co2.
          And as best I can tell it’s the water content that matters.

      • Gee we skeptics make up only 3%, everybody including elected government, its enforcers and useful idiots are castigating, investigating, insulting, and even threatening bodily harm, imprisonment, etc. and one of their numbers (something else) tells us we lack credibility! I have to admit, even I’m surprised that the handful of serious skeptics (a proportion of the 3% ARE unthinking contrarians and politically motivated who not only don’t contribute, but detract from the skeptic’s efforts and give the masses ugly labels to stick on all skeptics) have struck so much fear into the hearts of the enormous throngs of the settled science folks who will be turning their lights out for an hour tonight and want to turn them out for all of humanity for all time.

      • That’s funny, one comment that illicits a number of responses and I’m the one the protests to much? Seems more like I struck a nerve.

      • Yeah, but (someone else) you clones out number us over 30 to one! I call that bullying although I have a principle – I never engage in a battle of wits with unarmed opponents. Old joke: There we were 2 against 100, boy did we ever kick the spit out of those 2 guys!

      • Someone else,
        How exactly is the ‘greenhouse effect’ well documented? What precisely is it that is well documented? The fact that CO2 and H2O absorb IR at certain wavelengths? Or the assumption that this property somehow warms the surface of the Earth?

    • The sun provides three basic types of solar energy waves: ultraviolet (UV) waves, visible light waves, and shortwave infrared light waves. Each of these light waves has a relatively short wavelength compared to longwave infrared, and will pass easily through most types of relatively clear greenhouse coverings. Once inside the greenhouse, the waves are absorbed by plants and the ground and are used for photosynthesis as well as generally warming things up, which also produces humidity through evaporation. That energy is then transformed into thermal, or heat energy. Moist air can hold more heat than dry air and a greenhouse is notorious for producing humid air. Because thermal energy has a much longer wavelength than light waves, it cannot pass back through the greenhouse covering, and remains trapped inside. Venting is used as needed to relieve built up heat. You can even buy motorized openers that include an internal thermostat you can set so you don’t have to vent manually. The combination of trapped longwave thermal energy and humidity requires the use of fans and/or venting.
      The Earth is not like a greenhouse in that the Earth leaks thermal energy far more readily and far more inconsistently compared to a real greenhouse, as can be seen when measuring outgoing longwave radiation. It is far more complicated than that of a greenhouse and I think the use of that term confuses many skeptics.

      • Pamela,
        None of that discredits the similarities that I pointed out between the way a greenhouse works and the effect of subsidence warmed descending air (half the atmosphere at any given moment).
        As for humidity that comes from the ground and vegetation and builds up when convection is restrained whether inside a greenhouse or beneath a descending column of air.
        I know I have it right from long established meteorological principles.

      • “Each of these light waves has a relatively short wavelength compared to longwave infrared, and will pass easily through most types of relatively clear greenhouse coverings.”
        But not water vapour, it has considerable absorption bands in the solar near infra-red.

      • “But not water vapour, it has considerable absorption bands in the solar near infra-red.”
        =======================================================
        yes indeed. I forget the amount of TSI water vapor, clear sky absorbs, but it prevents a great deal of energy from even reaching the surface. I am not certain the residence time of this energy, failing to reach the surface, including the oceans, is properly considered.

      • “I am not certain the residence time of this energy, failing to reach the surface, including the oceans, is properly considered.”
        The average probably is. But the distribution is most likely being overlooked. In the horse latitudes there would more than average solar NIR warming the oceans, because of less water vapour.

  31. Let’s not forget about other forcings. I live in central North Carolina and wind direction means a whole lot about temperatures and air masses regardless of season.
    A northeast wind brings air from the North Atlantic. North and northwest winds come in from central Canada. West are maritime all the way from the Pacific. Southwest are generally dry from Texas and beyond. South is from the Gulf of Mexico and Southeast is off the Gulf Stream.
    Depending on the prevailing pattern we can be tropical-like, polar-like or desert-like and at our latitude of 35N and the season, it can switch fairly rapidly from one to the other.

  32. An instructive paper (as usual) from Willis, coupled with instructive discussion. This is what WUWT is all about. Thanks everyone!

  33. Thanks, Willis. It is fun to read you messing about.
    And yes, of course, water vapor is the most important atmospheric content, weather/climate wise. It is amazing to watch WV in the GOES pictures.

    • Not very good at all. It turns large areas with continental climate into desert (e. g. Siberia around lake Baikal, parts of Canada). It also misses one of the world’s most extreme deserts Rub al’Khali because of the moderating effect of the Indian Ocean. Incidentally I know from personal experience of the area that the effect does not extend nearly as far inland as on the map, presumably this due to “smearing” of coastal weather station and the absence of inland stations.

  34. Willis,
    Since you say “based on surface conditions” I see two issues that cripple the Brunt model. First, in wet atmosphere there is a continuum spectrum from water vapor dimer, which has little effect in dry atmosphere; so, a better model would have two sets of constants, a1 and a2, or parameters dependent on vapor pressure. The second issue is that infra-red emission is a function of local temperature (if local thermodynamic equilibrium is a reasonable model) and so a better model would have to include lapse rate. I’ll bet one could construct a greatly improved model not much more complicated than the Brunt model. I have little familiarity with the literature here, so what are other models you might have considered?

  35. The other side of the DLW radiation is here [click on ‘Global Temperatures’ on the left sidebar, then click on ‘Outgoing longwave radiation Global’].
    They have to balance, or the planet will tend to either warm or cool.

    • From the DNI global map it looks like we only need to get rid of China and global warming is solved !

    • According to that map Takla Makan, one of the World’s driest deserts has a lower DNI than Labrador. Must be due to the dust storms for which Takla Makan is notorious. Even so it’s odd.

      • tty Most SW USA appears to have higher DNI than the Sahara – with some interesting pros/cons to put it politely.

  36. That story is similar to Bullwinkle in that it is rife with political/social commentary of the day.

  37. Willis, something is precise in the combination of errors of the two methods. Note even the tiny desert on the South Island of New Zealand. Otago is a dry area in the middle of the island. During the 1800s gold rush days they cut runnels in the rock and dug ditches to bring water into the interior for gold sluicing.
    http://www.naturespic.com/i/32571XA00_w.jpg

  38. Ah, yes, Christopher, it was Ratty … teach me to trust my memory rather than go to the source …
    w.

  39. My little experiment. What am i doing wrong, I can sit near the fire sideways ( representing the sun) i get a large copper spoon and reflect the fires heat onto my face.
    My face being the earth? lower atmosphere, One side of my face is hot from the fire, the other facing away is cold. I can direct the fires heat onto my cold side with the copper spoon – amazing the heat it gives, feels about the same as the side facing the fire. So now i move the copper spoon to face the fire and the side of face facing the fire. So double warming and back radiation – this side feels no warmer with or without the spoon. I thought back radiation or double reflection from the fire would make it seem warmer- that seems to be the premise behind gorebull warming.

    • You feel the flux of the differences in temps between the fire and your face, the difference the spoon adds is minimal, so it feels and is approximately the same.
      BTW a gold spoon would work better.

    • Another problem with your spoon (if I understand the geometry of the setup…and I am not sure I completely do) is that it absorbs or reflects the radiation from the fire effectively. Greenhouse gases absorb the Earth’s infrared radiation effectively but do not absorb very much in the near infrared, visible, and ultraviolet, which are the wavelengths that the sun radiates. So, they act sort of like a 1-way mirror (not a precise analogy, because they absorb and subsequently emit, rather than reflecting…but close enough).

      • It is said that a hotter body emits more energetically at all frequencies than a cooler body so there should be more solar IR at 15 microns than terrestrial. Is there?

      • micro6500,
        I was aware that the sun is much warmer than the Earth.
        My question to you would be; how many watts per square meter are measured at TOA at 2 microns (solar) and why are there suddenly zero at 3 microns?
        Are you encouraging me to disbelieve that hotter bodies emit more energetically at all frequencies?

      • The Sun emits more IR per unit area of its surface. But it is a long way away, and occupies less than 1/10000 of the sky. The thermal IR that we get from the rest of the sky far exceeds solar (thermal) IR.

        • Nick,
          I don’t see how that possible, for instance I stuck the IR thermometer out the door tonight, and the sky measured -70F, where the ground is a balmy 20F or so.

      • joeldshore said:
        “Greenhouse gases absorb the Earth’s infrared radiation effectively but do not absorb very much in the near infrared, visible, and ultraviolet, which are the wavelengths that the sun radiates.”
        False. Water vapour has several strong absorption bands in the solar near infrared. And solar NIR provides some 49% of surface heating.

      • In support of Nick’s point, think about it this way: The Sun emits a certain amount of Power P (energy/second) in Watts. At its surface, that power is spread out over a spherical surface that has the radius of the sun R_sun, so the intensity (in W/m^2) is P/(4*pi*R_sun^2). However, by the time that power reaches the earth, it has spread out over a spherical surface that has a radius equal to the distance from the Earth to the sun, d_EarthSun, so the intensity is reduced to P/(4*pi*d_EarthSun^2). If you put in number for the sun’s radius and the Earth-sun distance, you find the intensity is reduced by a factor of ~46000 from what it was at the surface of the sun.

      • Ulric,
        By saying that they don’t absorb very much, what I meant was that a detailed calculation shows that the amount of Earth’s emitted radiation that is absorbed by the atmosphere is considerably larger than the amount of the Sun’s radiation that is absorbed by the atmosphere.
        Sorry if that was unclear to you.

      • micro6500 says:

        I don’t see how that possible, for instance I stuck the IR thermometer out the door tonight, and the sky measured -70F, where the ground is a balmy 20F or so

        Let’s show you how it works out, at least roughly. The intensity of radiation from an object is proportional to its absolute temperature to the 4th power, which is 5800 K in the case of the sun and, say, 255 K in the case of the Earth’s atmosphere. (Your -70F is at a particularly cold location/ time of year…255 K is probably still not exactly right since it is the effective radiating temperature of the atmosphere as seen from space, not as seen from Earth, but it’s in the ballpark.)
        Then we have to factor in the solid angle that the sky subtends vs. the solid angle that the sun subtends. For the sky, it is simply 2*pi steradians of solid angle (see http://en.wikipedia.org/wiki/Solid_angle ). For the sun, it is the pi*(angle that the radius subtends)^2 where the angle is ~0.25 deg and that works out to be 0.000068 steradians. The total intensity received at the earth’s surface from each object is proportional to the product of the intensity where it was emitted times the solid angle subtended (modulo discussion below).
        Not worrying about constants of proportionality that are the same for both, I get [(5840)^4]*(2*pi) = 6.76×10^10 and [(255)^4]*(2*pi) = 2.66×10^10, so you can see how they end up at the same order of magnitude. In this simplistic calculation, the intensity received from the sun is still greater than from the atmosphere; however, the solar result has to be reduced by a factor of 2 to account for the fact that the sun is only in the sky for half the time and by a factor of ~0.54 to account for absorption and scattering of solar energy by the atmosphere (see, e.g., http://www.aps.org/units/fps/newsletters/200904/trenberth.cfm ). Those two factors make the intensity due to the sky larger than that due to the sun.
        [Really, the calculation of intensity at the surface involves an additional factor of cos(theta) where theta is the angle in the sky from the vertical…But we are just trying to get a roughly-correct result here, not a precise calculation.]

        • joeldshore commented

          Let’s show you how it works out, at least roughly.

          Thanks for the details.
          Okay, but at the same time the Sun is down, the rest of the sky is still -70F, what you find is that it’s the dirt that is slow to cool at night, air temps at the surface cool quickly until rel humidity gets into the 80-90%, then air temps cool slower. But in the morning, you find the dirt is 5-10F warmer than the warmest thing around, the air. And your grass is 10-20F colder than the air!
          Dirt 5-10F warmer than the air, grass 10-20F colder than the air at the surface, and the sky is antarctic in the winter cold.
          Then, you have the ratio of Sunshine during the day to how long it’s dark and radiating madly to space at night.

      • mebbe
        March 28, 2015 at 7:46 pm

        micro6500,
        I was aware that the sun is much warmer than the Earth.
        My question to you would be; how many watts per square meter are measured at TOA at 2 microns (solar) and why are there suddenly zero at 3 microns?
        Are you encouraging me to disbelieve that hotter bodies emit more energetically at all frequencies?

        Might just be scale
        http://tornado.sfsu.edu/geosciences/classes/m407_707/Monteverdi/RadiationStuff/energy_wavelength.gif
        This has an energy scale.

        joeldshore
        March 30, 2015 at 8:59 am
        In support of Nick’s point, think about it this way: The Sun emits a certain amount of Power P (energy/second) in Watts. At its surface, that power is spread out over a spherical surface that has the radius of the sun R_sun, so the intensity (in W/m^2) is P/(4*pi*R_sun^2). However, by the time that power reaches the earth, it has spread out over a spherical surface that has a radius equal to the distance from the Earth to the sun, d_EarthSun, so the intensity is reduced to P/(4*pi*d_EarthSun^2). If you put in number for the sun’s radius and the Earth-sun distance, you find the intensity is reduced by a factor of ~46000 from what it was at the surface of the sun.

        An IR thermometer shows this to be wrong, While I can point it straight up and measure a temp as much as 90F colder than the ground (70F colder is pretty typical), and then point it in the direction of the Sun, don’t even have to point it and it reads over scale at over 600F.
        So, we have measured IR of well over 600F from the Sun, and on the same day can measure -70F from overhead, and -30 to -40 @~10-15 degree’s about the horizon.
        -40F is ~160 W/m2, but you do have to add the flux from Co2. Anthro Co2 is about 3.2 W/m2, total Co2 is a lot more than this, but I don’t see it equaling the Sun, nor do I think it’s 300W/m2. Now clouds are within 10 or 20F of the surface.
        The point is the Anthro Co2 is a fraction of the GHG forcing, and for it to do anything it have to overcome the energy involved in multiple state changes of thousands of times the mass of water.
        You can see this here.
        https://micro6500blog.files.wordpress.com/2015/03/relhumidity_withtemps.png
        As it warms in the spring rel humidity goes up, until temps peak then you see the relationship between increasing temps and increasing rel humidity changing, when you see this in electronics it indicates you’ve transitioned into an non-linear mode of operation. In this case it creates an energy barrier to more moisture, and maybe higher temps.
        Once temps start to go down, when you include dew point, you see they daily temp record hitting the dew point every night. Another non-linearity in temp water response, another energy barrier. It is also yet another restriction of water vapor.

      • @joeldshore
        March 30, 2015 at 9:02 am
        Nonsense, you said:
        “Greenhouse gases absorb the Earth’s infrared radiation effectively but do not absorb very much in the near infrared, visible, and ultraviolet, which are the wavelengths that the sun radiates.”
        Water vapour has considerable absorption bands in the solar near infrared.

  40. I would like to see a graph that shows amount of IR energy downwelling (and upwelling) versus altitud either theoretical or measured. Then try to compare that to Global Climate models.

  41. Its the water vapour, stupid……..
    Seriously, this does seem to call in question the role of CO2, even for CO2 believers. If the CO2 signal can be lost in a fog of water vapour feedbacks, then what role does it really play? You may as well say that the worst climate forcers are not the power station smoke stacks, belching CO2, but the power station cooling towers, belching water vapour.
    Ralph

    • ralfellis March 28, 2015 at 11:20 am
      Its the water vapour, stupid……..
      “….., but the power station cooling towers, belching water vapour.”
      Now there’s a thought. And I criticised an AGW article recently for showing a picture of a cooling tower belching H2O! Maybe they were right all along.

    • The amount of water vapour from cooling towers is trivial, but there is good evidence that large-scale irrigation (=increased evaporation) has significant local climatic effects, particularly on night temperatures.

    • ralfellis: The point is that humans cannot directly affect the amount of water vapor in the atmosphere very much, at least on global scales. This is because there is a lot more water vapor in the atmosphere (than CO2), because there are lots of huge sources of water vapor, and because water vapor cycles through the atmosphere quickly (i.e., it rains out).
      CO2, on the other hand, we can and have been dramatically increasing the concentration of in the the atmosphere. And, of course, as CO2 increases and the world warms, more water vapor enters the atmosphere through evaporation.
      So, in other words, we affect the concentration of water vapor indirectly by increasing the concentration of the long-lived greenhouse gases. This is why water vapor is considered to be a feedback, not a forcing.

      • And yet there is no actual observational evidence of the water vapor content of the atmosphere increasing and indeed no evidence that increased CO2 has in fact caused the air to warm.

        • Right, surface stations show no real change in rel humidity (~69-70%), and no loss of nightly cooling.
          And in fact I think I know why, and night when it cools off, high rel humidity limits the maximum amount of water vapor. So I don’t think it is possible to get anymore positive feedback from water than there already is.

      • Actually it’s absolute humidity that matters, not relative. However absolute humidity hasn’t increased either. Actually there is no strong theoretical reason to believe that absolute humidity would increase with temperature. The result could just as well be a slight increase in cloudiness and/or a slightly shortened atmospheric residence time instead.

      • joeldshore March 28, 2015 at 1:46 pm
        I said observational evidence, not inferred from GIGO, worse than worthless, worse than waste of taxpayer dollars models and reanalyses.
        What observational evidence exists shows just the opposite of the totally unwarranted model assumptions, ie steady or falling humidity levels since the 1970s.
        file:///C:/Users/John/Downloads/Inogwabini%20et%20al%202006%20Change%20in%20rainfall%20in%20Mabali.pdf
        Genuine climatology was replaced by “climate science”, ie computer modeling instead of observation.

      • Sorry. That didn’t work.
        Search for:
        © THE INTERNATIONAL JOURNAL OF METEOROLOGY
        October 2006, Vol.31, No.312
        A DRAMATIC DECLINE IN RAINFALL REGIME IN THE
        CONGO BASIN: EVIDENCE FROM A THIRTY FOUR-YEAR
        DATA SET FROM THE MABALI SCIENTIFIC RESEARCH
        CENTRE, DEMOCRATIC REPUBLIC OF CONGO

      • Sturgis,
        My bad…I thought when you said “there is no actual observational evidence”, you meant there is no actual observational evidence when in fact what you seem to have meant is “there is no actual observational evidence except for all of the observational evidence that does exist and which I therefore dismiss because it disagrees with my pre-determined conclusion.”
        What I linked to were evidence provided primarily by satellite observations, you know, the same sorts of observations that Spencer & Christy use to construct the UAH data set. Do you dismiss that too?
        Oh, and the link you provide to prove your point is even more bizarre. It is the fact that there is an area on Earth where rainfall is decreasing. In fact, the last paragraph of that paper reads in part:

        In conclusion, rates at which the climate is changing may be greater todaythan at any time in the last 10,000 years (e.g. Houghton et al., 1990). In particular, increases in the concentration of ‘greenhouse gases’ are thought to be contributing to a gradual but steady increase in global climate change with its severe implications (e.g. Myers 1985, Wescoat & White 2003). Projected effects of the accumulation of greenhouse gases on the atmosphere were documented to principally affect rainfall regimes and temperatures, and therefore water basin regimes in different degrees (e.g. Dawson 1992, Hugget 1993, and Wescoat & White 2003). Tropical forests, though luxuriant in their splendid appearance, are a mixture of fragile microhabitats and ecosystems (Richard 1996) that are very sensitive to water (rainfall and river basin regimes) and other climatic fluctuations (e.g. Myers 1985). Therefore, tropical forests hold a potential to serve as laboratories to gauge these effects.

        So, it looks like the authors of that study would not in any way agree with your bizarre interpretation of it.

      • Joel:
        Satellites do not show more moisture in the atmosphere during the alleged warming during the satellite era. Only manipulation makes the supposed increased moisture appear. Even Chung, et al, 2014, before going on to engage in hijinks with the observed data, have to admit, to their credit, that, “Changes in upper-tropospheric water vapor have been examined based on satellite-observed radiances of 6.7-μm water-vapor channels (notes), which are closely related to the layer–mean relative humidity in the upper troposphere (note). Decadal trends in upper-tropospheric relative humidity exhibits distinct regional patterns associated with changes in the atmospheric circulation, but the decadal trends over larger domains are small due to opposing changes at regional scales (note). Analyzing the globalscale changes in 6.7-μm water-vapor radiances reveals little change over the past three decades.”
        http://www.pnas.org/content/111/32/11636.full.pdf
        I didn’t have to “interpret” the African data, since it plainly showed stable humidity. It’s your interpretation that is strange. But then, as a practitioner of post-modern “climate science”, ie computer modeling based on assumptions not in evidence rather than observing nature, no wonder.

      • It certainly is not easy finding papers on absolute humidity. The following is rather ambiguous in its conclusion and cautions those who are investigating this part of AGW theory. I would advise you Joel to do the same.
        http://scholar.google.com/scholar_url?url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.1.1.370.5414%26rep%3Drep1%26type%3Dpdf&hl=en&sa=T&oi=gga&ct=gga&cd=8&ei=vG4XVbTACMKRqQH-tYDICg&scisig=AAGBfm370GZaVs0TnVRfcIhEyXBIvTzMeg&nossl=1&ws=1600×747

      • Sturgis,
        Your latest reply shows you have a basic misunderstanding of your prediction. You quote a paper that says that there has been little or no global change in RELATIVE HUMIDITY (which was also what the African paper said) thinking that it supports your point when in fact it completely undermines it. The prediction of climate models is in fact exactly this, i.e., that as the Earth warms, absolute humidity will increase in such a way that, on the global scale, relative humidity will remain roughly constant. (In fact, I think if they show any trend, they show a very slight downward trend in relative humidity.) Relative humidity is the ratio of the absolute humidity to the humidity at saturation and the latter is a steeply increasing function of the temperature.
        Thanks for providing us with additional evidence that this prediction is correct and your original claim that “no actual observational evidence of the water vapor content of the atmosphere increasing” is wrong!

        • ” relative humidity will remain roughly constant. (In fact, I think if they show any trend, they show a very slight downward trend in relative humidity.) ”
          What I recall from my data (NCDC GSOD) that rel humidity has a slight downward trend, but theory says there’s to be an increase as positive feedback, which based on the trend it looks like a dud.
          At best rel humidity is acting like normal.
          Or are you saying that normal rel humidity is a sign of AGW?

      • Pamela,
        Paltridge et al. took a data set…a reanalysis by the way, which Sturgis tells us is GIGO…that the creators of the set warned was not reliable for long term trends and used it to look at long term trends. As has been shown by Dessler et al., this one reanalysis gets results that are different from all the others and from the satellite data: geotest.tamu.edu/userfiles/216/Dessler10.pdf It also gets results that are in complete contradiction to what are seen for the relationship between temperature and humidity for fluctuations on shorter time scales, where you don’t have to worry about changes in instrumentation and the like introducing artifacts.

      • Sturgis: It is worth summarizing what you have done here as an illustration and cautionary tale of how science gets abused by those like yourself who have a strong agenda that happens to run counter to the overwhelming scientific evidence. You referenced this paper: http://www.pnas.org/content/111/32/11636.full.pdf even though you didn’t like most of what it said, so you dismissed the part you didn’t like (which was almost all of it) as “hijinks” and cherry-picked one quotation that you THOUGHT supported your point, when in fact, it completely undermines your point.
        This is a sad testimony of the kind of nonsense that the scientific community has to deal with from people when those people are ideologically opposed to the scientific conclusions.

      • Sturgis Hooper says:
        And yet there is no actual observational evidence of the water vapor content of the atmosphere increasing and indeed no evidence that increased CO2 has in fact caused the air to warm.
        Correctomundo. And since joelshore disputes it with his usual politics argument [“agenda”], we can be sure of who is right, based on empirical observations.
        Hooper is correct, specific humidity has been declining:
        http://clivebest.com/blog/wp-content/uploads/2013/03/SH400mb.jpg
        Relative humidity has also been declinging, which is why the predicted tropospheric “hot spot” never appeared:
        http://clivebest.com/blog/wp-content/uploads/2013/03/GlobalRelativeHumidity300_700mb.jpg
        If there was long term global warming, humidity would be increasing. But it’s not. Therefore, the predictions of man-made global warming are a steaming pile of carp. QED, as they say.

      • Thanks, dbstealey, for further lowering the discourse by pasting graphs from the right-wing propaganda website Friendsofscience.org with absolutely no reference to where the data comes from. I believe it is from the same reanalysis that Paltridge et al. used and has already been debunked here, but perhaps dbstealey can fill us in on the details and provide perer-reviewed references.

      • joelshore says:
        Thanks, dbstealey, for further lowering the discourse by pasting graphs from the right-wing propaganda website… &blah, blah, etc.
        As usual, joelshore is out to lunch. Instead of debating science, he attacks the provenance of the graphs I posted — just another type of the discredited ‘Appeal to Authority’ fallacy.
        In fact, those graphs came from here. There are lots of other graphs there, too.
        These graphs show the same thing; humidity is declining:
        https://wattsupwiththat.files.wordpress.com/2014/07/noaa20esrl20atmospericspecifichumidity20globalmonthlytempsince194820with37monthrunningaverage1.gif
        https://wattsupwiththat.files.wordpress.com/2014/07/noaa20esrl20atmospericrelativehumidity20globalmonthlytempsince194820with37monthrunningaverage1.gif
        Shore constantly inserts his far-Left politics into science discussions. Graphs of humidity are not “propaganda” — except in the minds of deluded numpties who still cannot admit they were flat wrong about man-made global warming [MMGW].
        If there was real global warming happening, there would be more evaporation, and humidity would rise. But humidity has been declining for decades — another piece of real world evidence that debunks the MMGW scare that is still being purveyed by the alarmist cult.

      • Yes, dbstealey, we all know that you got that data from Ken Gregory of the Friends of Science, just as I said. Now, you are going around and finding this same debunked data ( http://geotest.tamu.edu/userfiles/216/Dessler10.pdf ) plotted on different websites.
        That’s what fake skeptics do: They uncritically accept a debunked piece of data that supports their point of view and ignore the mountain of better data that refutes it.

      • joeldshore, from the Dessler et al paper:
        Based on the available evidence, it is our judgment that negative trends in the tropical mid and upper troposphere in response to long‐term climate change are spurious. This is clearly the most parsimonious explanation, and it is in accord with virtually all of the independent lines of evidence (models, observations, theory, and newer reanalyses). Clearly, however, our analysis emphasizes the need to understand and reduce the uncertainties in long‐term trends from reanalyses, and this goal should be a high priority of the community.
        That is not a “debunking” of the humidity declines, but a different theoretical interpretation based on models, some of which are known to be unreliable. He does not actually define “spurious”, but it usually refers to something in the data that is independent of the most interesting cause being studied.

      • joelshore says:
        Yes, dbstealey, we all know that you got that data from Ken Gregory of the Friends of Science, just as I said.
        “We all know”??
        What a deluded jamoke. As I plainly stated, I copied those charts from WUWT, “just as I said” — proving that joelshore is a know-nothing.
        More nonsense:
        That’s what fake skeptics do: They uncritically accept a debunked piece of data that supports their point of view and ignore the mountain of better data that refutes it.
        …says the Numpty who has no data or charts of his own to counter the evidence of declining humidity. Shore emits psychological Projection like it’s coming out of a firehose. Everything is political to him; his ‘science’ is only a thin veneer of baseless assertions, as we see right here.
        joelshore is the quintessential guy who could never make it in the real world. He only gets by in a tenure-protected ivory tower of like-minded fools. The government .edu establishment is a national disaster, as anyone can see who reads the papers. The reason is clear: it is populated and controlled by fuzzy-thinking Leftist chumps, who have been trained with grant funds the same way that Pavlov’s dogs were trained with dog biscuits.

      • Joel, the combustion of hydrocarbons generally produces twice as much water as CO2. So while there is great hue and cry over human CO2, nobody seems to even consider human water emission of twice as many molecules. In a microclimate setting (like airport thermometers) this seems far from insignificant.
        So in the deserts the well mixed and well heeled “forcing” GHG seems unable to produce Jack DLR on its own. Explain why I should believe the second string “feedback only” GHG needs any help from this pitiful “forcer” in the humid areas?

      • dbstealey says:

        What a deluded jamoke. As I plainly stated, I copied those charts from WUWT, “just as I said” — proving that joelshore is a know-nothing.

        Let me help you out by reading the first line of the WUWT page that you linked to: “Guest post submitted by Ken Gregory, Friends of Science.org”

        …says the Numpty who has no data or charts of his own to counter the evidence of declining humidity.

        I don’t present charts that I don’t understand from strongly-ideological sources, removed from all their context so that people can’t even tell where the data originally comes from. Instead, I link to the peer-reviewed papers on the subject, which is what I have done here. I will refresh the relevant links here for your memory (and adding the one that Sturgis kindly provided):
        http://www.sciencemag.org/content/323/5917/1020.summary
        http://www.sciencemag.org/content/310/5749/841.abstract
        http://geotest.tamu.edu/userfiles/216/Dessler10.pdf
        http://www.pnas.org/content/111/32/11636.full.pdf
        You can find more by looking at the references of those links.

      • gymnosperm:

        Joel, the combustion of hydrocarbons generally produces twice as much water as CO2. So while there is great hue and cry over human CO2, nobody seems to even consider human water emission of twice as many molecules. In a microclimate setting (like airport thermometers) this seems far from insignificant.

        I’ve already explained why this is basically insignificant on the global scale. It might have some microclimate effects, although even those are limited by many factors…such as the fact that the effects tend to be logarithmic in concentration, which means that it is fractional changes in concentration that matter and since the concentration of water vapor is higher, it takes a much larger quantity of water vapor to, say, increase the fractional concentration by 10%.

        So in the deserts the well mixed and well heeled “forcing” GHG seems unable to produce Jack DLR on its own.

        And, you know this how? I see nothing in Willis’s data that shows you how much DLR is produced in the deserts. Yes, it is down by 50 W/m^2 or so from wetter areas but my guess is that it is still quite significant, given that the average amount of DLR globally is about 330 W/m^2 ( http://www.cgd.ucar.edu/cas/Topics/energybudgets.html ).

        Explain why I should believe the second string “feedback only” GHG needs any help from this pitiful “forcer” in the humid areas?

        Because physics tells us that in the absence of the non-condensable GHG’s, the atmosphere would be enough colder that there would be significantly less water vapor in it (which would then make it colder still). And, if you don’t believe in the water vapor feedback when you go up in temperature, you have to believe in it when you go down in temperature…since you would end up with more water vapor in the atmosphere than it can hold when fully saturated if you try to insist that water vapor concentration does not decrease as temperature decreases.

        • Joel, last night my IR thermometer measured a zenith temp of ~-70F, with an air temp of about 20F, and it just clouded up with an air temp of 42F and zenith temp of ~ 33F. What’s the forcing in W/m2 of the sky compared to your 300 some?

      • matthewrmarler says:

        That is not a “debunking” of the humidity declines, but a different theoretical interpretation based on models, some of which are known to be unreliable. He does not actually define “spurious”, but it usually refers to something in the data that is independent of the most interesting cause being studied.

        If you can get beyond the fact that the mentioned the (apparently for you guys) evil word “models”, you’ll see that, as he says, the conclusion is based on “independent lines of evidence (models, observations, theory, and newer reanalyses)” and all of this is explained in the paper. It’s an extremely thorough debunking.
        Anybody who accepts that one reanalysis with all of its deficiencies and ignores the wealth of data and other evidence that goes the other way is doing not for any valid scientific reason but rather because that one reanalysis tells them what they want to believe.

      • joelshore says:
        I don’t present charts that I don’t understand…&blah, blah, etc. So he doesn’t understand? Everyone else does.
        Followed by the usual “ideology” comment, which make his comment political — not scientific. As usual.
        And why would joelshore argue science, anyway? He’s already lost that debate, faced with the fact that humidity is declining.

  42. –This one was funny to me because it was such an excellent and detailed map of the desert and arid areas of the planet. —
    It doesn’t seem to show the desert of Antarctic. And the State of Washington
    is fairly wet. And Seattle, Washington and western part of BC Canada are temperate rainforests. And generally poleward regions are drier.
    But mainly I wonder about the Antarctica:
    “To be considered a desert an area must have less than 250 millimeters of annual rainfall. Using that criteria, the continent of Antarctica is the largest desert on Earth. It has less than 51mm of precipitation per year and little or no vegetation.”
    http://www.universetoday.com/73868/what-is-the-largest-desert-in-the-world/

    • Willis seems to have assumed 100% relative humidity in the formula, which is probably reasonable for Antarctica, but shows as a discrepancy for warmer deserts.

      • Still that doesn’t explain the discrepancies. If Willis uses 100% RH that means that he will get the maximum possible value for NLM according to Brunt’s formula and that the Ceres values should all be identical to or lower than the Brunt values. That clearly isn’t the case. More likely he used Brunt’s actual values (which seem to imply 50 % RH). In which case this seems to be a neat method to determine the RH on a global basis.

      • “Still that doesn’t explain the discrepancies. “
        Well, there’s more. Willis says Brunt’s formula is
        “The Brunt method estimates the “effective emission” as a function of the form
        a1 + a2 * vapor_pressure

        But it is actually
        a1 + a2 * sqrt(vapor_pressure)
        That is going to create a few discrepancies.

      • Nick Stokes March 29, 2015 at 2:11 pm

        “Still that doesn’t explain the discrepancies. “

        Well, there’s more. Willis says Brunt’s formula is

        “The Brunt method estimates the “effective emission” as a function of the form
        a1 + a2 * vapor_pressure”

        But it is actually
        a1 + a2 * sqrt(vapor_pressure)
        That is going to create a few discrepancies.

        Thanks, Nick. The calculation was done properly, but the description in the head post was not. I’ve corrected it.
        Regards,
        w.

    • It is cute to include the polar regions as deserts but rainfall amount as a criterion was intended only for arid hot lands because the features we have come to know about the hot kind form under these conditions. It would be ridiculous to lump the polar regions in with the hot deserts because, excluding the oceans, these places have more water than anywhere else on earth. The radiometers in the satellites haven’t been let in on the joke, so they don’t get it. Also, 100% humidity occurs in pretty dry air only if it is exceedingly cold (based on the definition of relative humidity).

    • “It doesn’t seem to show the desert of Antarctic. And the State of Washington
      is fairly wet. And Seattle, Washington and western part of BC Canada are temperate rainforests.”
      Look more closely. Washington state east of the Cascades is not wet. It is part of the Great Basin and semi-desert.
      “But mainly I wonder about the Antarctica”
      Note that the map shows differences in absolute DLR. DLR is very low in Antarctica so even a large percentage error there will be fairly small in absolute terms. Still, much of East Antarctica shows “near desert” error.

      • Since there’s discussion of what constitutes a desert and gbaikie has invoked the term “temperate rainforest” for Seattle and western BC, I’d point out that much of the west coast is a lot less rainy than many think.
        Seattle’s annual rainfall is around a meter (40″). Vancouver 1.2m. The appellation ‘rainforest’ typically calls for a minimum of 2.5m of annual precipitation, and it should occur fairly uniformly through the year. That is not the West Coast; there are 4 distinctly dry months.
        Forests of any kind don’t seem to thrive where there isn’t decent rainfall as evidenced by the 25cm in southern BC, east of the Coast Range (as you point out,tty); sage brush and scattered pine.

      • Actually You can’t put a fixed rain figure on “rain-forest”. A lot depends on the temperature (=evaporation). And a short dry season is not unusual in rainforest areas, check Manaos for example. In North America temperate rainforest climate is usually defined as >1400 millimeters rain with a mean annual temperature between 4 and 12 degrees Celsius. This means that places like Seattle, Vancouver or Olympia, which are all in partial rain-shadow do not quite have temperate rainforest climate, but the western side of the Olympics and Vancouver Island most definitely has!

  43. ( “Willis Eschenbach
    March 28, 2015 at 1:40 am
    Thanks, Wicked. We’re looking at clear-sky conditions in the map above (no clouds). Desert areas get very hot during the day because they don’t have many clouds. The effect of this is much larger than any decreases in daytime downwelling longwave.
    And they get very cold during the night because there’s little water vapor to absorb radiation and leave the earth warmer.
    So no, they don’t say much about the greenhouse effect.” )
    Sorry Willis, but Wicked is correct, deserts say EVERYTHING about the greenhouse effect !!
    In simplistic terms ( so CAGW devotees can follow the logic) –
    We are told, Ad infinitum, that CO2 is the main cause of global warming via Infrared reflection etc…….
    It is agreed that CO2 is fairly evenly-ish mixed in the atmosphere around the globe.
    So if CO2 is the main culprit, deserts would stay warm at night…but they don’t…unless there are clouds
    Therefore a simple proof that CO2 is not the main driver …but cloud is THE greenhouse gas.
    Sarc on-
    To save the world from imminent destruction, we urgently need a way that politicians can make serious personal fortunes by taxing poor people for creating water vapor !! – Sarc off.

  44. micro6500
    March 28, 2015 at 1:44 pm
    “Right, surface stations show no real change in rel humidity (~69-70%), and no loss of nightly cooling.”
    A good reason for this away from the effect of the oceans (where most stations are), it seems to me, is that if you have humidity in the day near the above levels, the dew point is reached at some time in the night and water is forced out of air as droplets on the vegetation. When the sun comes up, it just re-evaporates most of the same water back into the atmosphere (some of which has been taken up by the vegetation as it slips down to the roots) and adds some more from evapotranspiration. It seems one could calculate what the likely daily relative humidity average should be knowing the diurnal temperature variation and knowing that nighttime is ~100% humidity before dawn in the temperate zone. Add and subtract deserts, tropical zones and the rim of ocean affected land. A simple (simplistic?) model to be sure. Were I to have been asked to guess the figures, I would have said roughly around 70%.

    • And if I could figure out how to link the jpg of my weather station you can see how the average temp increases in the spring until it maxes out rel humidity on the high side in the summer, and the low side in the winter.
      I would have never guessed it did this even though I knew of all of the individual effects.
      [Reply: Just post the link, separately. It has to end in .jpg or .png or .gif to appear. Otherwise, readers will have to click on the link. ~mod.]

      • Micro,
        I hope you are able to post some graphical form of your humidity data. I have been watching intently with regards to the ~ 80% RH you have observed and commented on.

        • I don’t have a graph, but I do have the data. Now this is a straight average of stations that had at least 360 samples per year, but it isn’t weighted for distribution of stations and it probably should be.
          But the data includes dew point, I calculate Rel Humidity
          YEAR DEWPOINT RELH
          1940 40.56682644 75.34768165
          1941 44.24091639 74.97565368
          1942 44.45971805 71.45144152
          1943 48.52910657 68.21156434
          1944 47.20622234 68.58368678
          1945 48.92415329 70.02185462
          1946 46.15443042 71.94139546
          1947 44.61259741 70.85602068
          1948 44.4461462 69.10623409
          1949 43.74718298 68.89516838
          1950 43.04368306 69.42639585
          1951 43.86450442 69.32324362
          1952 42.81918995 67.84774625
          1953 44.66486394 67.82353649
          1954 44.74067333 68.41008572
          1955 44.97189331 69.33341908
          1956 44.32255233 68.67325051
          1957 44.88539286 69.36450976
          1958 44.54795943 68.15226773
          1959 43.90947345 68.17989382
          1960 43.20859712 68.02032403
          1961 42.49861668 68.96802513
          1962 41.98599219 69.00100279
          1963 41.61687443 68.71413467
          1964 41.50618815 68.02378888
          1965 41.49677782 68.43474935
          1966 40.55561334 68.54323846
          1967 41.51172772 69.03934749
          1968 41.08154826 68.15801744
          1969 38.29465457 69.28906119
          1970 35.09911457 69.28693236
          1971 43.25642281 66.0854363
          1972 43.42498767 66.80676248
          1973 42.97526167 69.31133555
          1974 41.02287683 70.27566127
          1975 38.82723865 69.58104188
          1976 38.16243391 69.30562984
          1977 40.65054845 68.85577927
          1978 39.78448988 70.22669152
          1979 40.14715555 69.79472106
          1980 38.77878518 69.88084667
          1981 40.31178052 69.57833066
          1982 40.54020181 70.71218634
          1983 40.64922774 70.74111249
          1984 40.02106401 70.4694655
          1985 38.69228449 70.99691469
          1986 39.49661508 70.62265641
          1987 39.6419206 71.08693085
          1988 39.46636274 70.27924484
          1989 39.79061357 70.86782886
          1990 41.27510356 70.69013438
          1991 41.31413254 71.14807546
          1992 41.44899262 70.18820229
          1993 41.66703505 70.11676981
          1994 42.43282258 69.70913829
          1995 42.85852681 69.6589601
          1996 43.00022387 70.24634663
          1997 43.58569476 70.1466172
          1998 44.27042243 70.58096154
          1999 43.56819776 69.96230073
          2000 43.37874393 70.31183227
          2001 43.23721187 69.85904807
          2002 43.37056012 69.80694885
          2003 43.16938149 69.59319163
          2004 42.93039789 69.55653173
          2005 42.71627221 69.01247888
          2006 42.63294836 68.89994799
          2007 42.8232091 68.5272092
          2008 42.16064641 68.82682172
          2009 42.62356904 69.51095147
          2010 42.41952692 69.47312855
          2011 43.08406857 69.29540385
          2012 43.42689236 68.27844709
          2013 43.23127161 69.0916613
          9999 is an average of all years.
          9999 42.37539614 69.58612645

  45. Joeldshore are you saying the ratio between natural and anthropogenic C02 is decreasing with anthropogenic being the driver?

  46. Willis, your maps even indicate the Taklamakan Desert, which is high and cold. Very interesting analyses and map. It appears to be better at indicating desert areas than the sinking hot air at about +/- 30 deg.
    I too love color maps and the eye can find much information in them.

  47. What, after reading all comments (some of which I can follow, others not so much) is as far as I can tell nobody seems to include the geographical features of our planet that help create deserts without doing a thing . They just kinda sit there, you know the Rockies, the Andes, Alps, Himalayas etc. The rain shadows they create have as much (if not more) to do with all the things I have read on this thread regarding deserts so far. (call me stupid). You all can talk about solar this, gases that reverse heat radiation etc but as far as I have experienced for decades as a farmer I look up at the mountain ridges and tops and they tell me more than a $100,000 a year weather guy

    • Rain shadow is important for some deserts (e. g. Takla Makan, Kyzyl Kum, Gobi, Great Basin), but not for others, that go straight down to the sea-shore (Sahara, Atacama-Nazca, Namib, Rub al’Khali).

    • asybot,
      I think I may be in the same or similar boat as you. A lot of most valuable understanding (e.g. large desert regions) may be being lost due to annual means and the likes. Large desert areas may be much influenced due to the lack of convection due to water vapor at low levels. But then that could be caused by the Hadley (hope I got that right) circulation pattern. I believe that the data needs to be reviewed in the desert regions on a much shorter time scale to get a better understanding.
      Willis’s emergent thermostatic hypothesis in the tropics seems good to me. Solve the deserts and we may be closer to reality. Since the ‘global warming’ meme started there has been too much misdirection from the ‘believers’ but those days are numbered.
      BTW, I see WUWT has passed the “one quarter of a billion” views this past week. There are a lot of real people looking at the real issues.

  48. Great – a ‘desert finder’!
    reproduceable, falsifiable.
    real world measurment of DLR + a robust, empirical backed formula.
    Thanks, Willis – Hans

  49. Nice work, Willis. Some time ago you spotted an error in a paper and corrected it. The author was furious that a mere non-scientist had the nerve to correct him. TS, I thought It is this attitude that makes their “climate” science accumulate a pseudo-scientific dogma that cannot be changed by the logic of science. If there is a breakthrough I expect it from people like you, not from these academics with outsized egos. Keep up the good work.

  50. Once again I get to enjoy a Willis piece.
    From some of the comments from others about “Well mixed CO2” I get the impression that your look at CO2 around the world still hasn’t sunk in yet. CO2 isn’t well mixed. There are definite highs and lows around the world. It isn’t quite like water vapor though, the delta between high and low values isn’t as extreme.

  51. Kristian March 29, 2015 at 11:38 am

    wickedwenchfan,
    You’re right. It does say something about the ‘greenhouse effect’. The atmospheric ‘greenhouse effect‘ is after all supposed to make the surface below warmer (its temperature higher) ON AVERAGE. Clouds allegedly contribute significantly (~25%) to this atmospheric ‘greenhouse (average, net warming) effect’.
    Problem is, the AVERAGE (annual) sfc temps in tropical/subtropical desert and generally dry areas are consistently higher, not lower, by several degrees (corrected for altitude) than the ones in tropical/subtropical rainforest and generally wet areas.

    Mmm … thanks, Kristian, but I fear you and wickedwf are oversimplifying. The great global desert belts have a variety of physical differences from “tropical/subtropical rainforest and generally wet areas”. These include:
    • Descending dry air. The great Hadley cells are driven by the tropical thunderstorms. These move air upwards, wring out the water, and send it poleward. This dry air descends at about 30° north and 30° south, and it is the reason for the existence and the location of the desert areas.
    http://wattsupwiththat.files.wordpress.com/2009/06/willis_image1.png
    The existence of this global belt of descending dry air has a variety of knock-on effects:
    • Fewer clouds. Because the descending air is dry, there’s little moisture in the arid areas to form clouds. This allows a much larger amount of the solar energy to make it to the surface, which leaves the desert area warmer than it would be otherwise.
    • Less absorption of solar energy by water vapor. In clear-sky conditions, about 78 W/m2 of incoming solar energy is absorbed by the atmosphere (CERES data). Somewhere around half of this, call it 40 W/m2, is due to absorption by water vapor. So the dry air allows more solar energy to make it to the surface.
    • Less vegetation. This has two effects. First, plants absorb solar energy and convert it to chemical energy. So a lack of plants allows for greater peak temperatures. Second, plants pull water up out of the soil and evaporate it (transpiration). This cools the area.
    • Drier soil. This has three effects. First, it directly reduces thermal mass, which allows for greater peak temperatures. Second, it reduces soil heat conduction. This has the effect of reducing the thermal mass involved in daily temperature fluctuations, and again leads to greater peak temperatures. And third, it reduces direct evaporation from the soil. This prevents evaporative cooling.
    Note that all of these effects are due to the lack of water. As a result, the 30° north/south belts of dry descending air have little effect over the ocean (see Figure 1).
    In any case, those are some of the reasons for the differences, there are others. As a result, it is by no means a simple referendum on the greenhouse effect.
    My best to you,
    w.

    • So water vapour acts as an anti greenhouse in the tropics and subtropics, it reduces maximum daytime surface temperatures. There are temporal and spatial claw-backs by means of the heat capacity of WV to the night time, and by advection to higher latitudes. And the whole system is set up to gather more solar near infrared in the horse latitudes, and with atmospheric rivers delivering strong water vapour warming to higher latitudes, biased towards the winter hemisphere. But what is the net balance?

      • Surface stations, when you look at yesterday’s rise and last night’s falling temps, over a year it’s slightly negative (more cooling).

    • We all know about these other effects, Willis. That’s exactly the point. You cannot under any circumstance look at a radiative budget alone and determine sfc temps. Not regionally. And not globally.
      The rGHE hypothesis seeks to derive directly the temperature of the surface purely from an atmospheric radiative balance (the lapse rate down working only as its extended arm). You get nowhere with such a simplistic approach. You will only fool yourself.
      The total energy content (the ‘internal energy’) of a thermodynamic system – like the Earth system – is certainly determined by the balance between its total energy input and output, in the context of the Earth system, simply the balance struck between SW IN and LW OUT through the ToA. Energy content is an extensive property.
      However, the specific temperature (an intensive property) of different subsystems inside the overall system can by no means be derived from this same balance/imbalance. The tropical dry/wet region comparison is a good case in point. This is where the rGHE hypothesis goes wrong. Internal temperatures would be set rather by differing ‘heat capacities’ and ‘internal movement’ of energy. The internal movement of energy between the subsystems inside the Earth system is governed almost exclusively by the process of convection/advection.

      • Kristian said:
        “Internal temperatures would be set rather by differing ‘heat capacities’ and ‘internal movement’ of energy. The internal movement of energy between the subsystems inside the Earth system is governed almost exclusively by the process of convection/advection.”
        Exactly right. Note though that both KE and PE are energy but only KE is heat.
        So you have to, somehow, get convective overturning to raise surface temperature above that predicted from the purely radiative S-B equation.
        What suggestion do you have other than the description of adiabatic processes that I have already put forward ?
        Either it must be radiation as per AGW or it must be atmospheric mass acting via adiabatic warming on descent and Willis’s findings are consistent with the latter but not the former.

    • Again, low RH, dry, does not mean low DLR. Above the Sahara there is appr. 380 W/m2 SW ‘available’ at TOA but at the surface net SW is only 170 W/m2, enough to keep the surface at -40 deg C. DLR is twice the net SW. The Saharan atmosphere is absorbing more than 100 W/m2 solar, much more than the global average, so stop this dry air misinformation.
      CERES-plots here: http://virakkraft.com/Sahara-rad.pptx

      • LGL
        The issue is not the absolute amount of DLR because however much DLR there is the thermal effect at the surface gets negated by convective adjustments along the lapse rate slope which is determined by the density gradation as one moves upwards. That density gradation being a consequence of the kinetic energy of the mass of the atmospheric gases doing work both with gravity on descent and against gravity on ascent.
        The issue is that regions with more GHGs do not warm as much as regions with less GHGs. Under AGW theory that is impossible.

        • lgl
          Those charts simply show that the tropics are warmer than other latitudes.
          In Willis’s version one can see clearly that there is less DLR over deserts and there is no doubt that sunny deserts become warmer under insolation than humid regions.
          You need to show the land surface chart to reveal that which is probably why you didn’t include it. That omission makes me doubt your integrity.

        • lgl,
          I wonder what the specific’s for those are. my experience with measuring SW IR is that when pointed straight up the temp measured is greatly dependent on the amount of water in the air, air temp and ground temp.
          Dry air overhead on a clear cool to cold day is very cold, -40F to < -70F, a 60F – 70F day with 60-70% rel humidity can be from 32F to 0F, cloud bottoms are 10-20 colder than surface temps, as much as 90F warmer than clear skies. The attribution of that SW is critical.
          So, while an all-sky reading when it's cloudy will have a very high SW flux, Clear dry skies there is far less SW flux, which is what Willis's chart shows.
          And TOA is a redherring, we live down here, and we have no past measurements prior to the 60's-70's to know what it did in the past.

      • micro
        I can’t tell from your writing but if I am to speculate you mean LW IR and you are using an IR thermometer in the 8-14 micron band, which is mostly within the atmospheric window, in which there is not much radiation from clear sky (but a lot from clouds) so the temp you are reading does not tell you much about the total LW.
        Regarding Willis chart I think all he has shown is that there is no globally valid Brunt formula, and that people working in this field already knew that.

        • micro
          I can’t tell from your writing but if I am to speculate you mean LW IR and you are using an IR thermometer in the 8-14 micron band, which is mostly within the atmospheric window, in which there is not much radiation from clear sky (but a lot from clouds) so the temp you are reading does not tell you much about the total LW.

          Yes, I did mean LW.
          Actually 8-14u is part of the main BB spectrum for environmental temps. So this should be right in the middle of the hole to well very cold temps. But this is what the surface see, You really need to add the energy in the 15-16u Co2 spectrum to this, but I think this can be calculated and then added to the rest of the skies LW IR flux.
          Water absorbs in the 8-14u spectrum that shows up nicely.
          When you get down too it, anthro Co2 isn’t a lot of forcing, and compared to the energy spent regulating rel humidity, Co2 doesn’t seem to impact night time cooling, and if it’s not restricting cooling it’s doing nothing to surface temps.

      • Stephen
        So your theory is invalid for 70% of the surface, nice to know. I didn’t use the JMA temp diagram because it goes in 5 deg steps. If you have one with 1 deg resolution I’ll be happy to include it. Anyway, much of the deserts are quite chilly on average because of high altitude and can not be compared to sea level.

        • The point was that temperatures get highest over deserts where GHGs are lowest contrary to AGW theory.
          You have, presumably deliberately, declined to show a land surface temperature chart which, when compared to the sea surface temperature chart would show the difference between lower sea surface temperatures beneath large amounts of GHGs (water vapour) and higher land surface temperatures beneath small amounts of GHGs (low humidity).

      • Stephen
        There is no “contrary to AGW theory” in this. (and is is standard GH theory, not AGW theory)
        I have told you, there is 170 W/m2 SW and 350 W/m2 LW to the Saharan surface. What more do you need to get the 30 or 35 C or whatever the average is? (Also remember the emmisivity there is somewhere around 0.9) Of course there are hot regions in some deserts, hotter than the ocean, and Willis has told you why, lack of water. Nobody has denied that.

        • lgl
          The DLR to the Saharan surface has no thermal effect due to the lapse rate.
          The absence of water for evaporation is not relevant for the S-B equation.
          The heat that develops above S-B is due to the restraint on convection beneath the descending air column.

        • lgl
          Please try to see it.
          The average temperature of the Earth’s surface is said to be 33C warmer than predicted by the S-B equation.
          AGW theory attributes that 33C to DLR from radiative gases.
          I say it is a consequence of descending air warming adiabatically (50% of the atmosphere is descending at any given moment) restraining convection from the surface below the descending column so that the surface rises 33C above S-B overall. The effect is just like a greenhouse as I explained before but a result of mass and not radiative capability.
          If radiative gases are present they radiate energy to space from witrhin the atmosphere which leads to less total energy (KE plus PE) in the descent leg of the convective cycle than was present in the ascent leg.
          That reduction in total energy in the descent offsets the potential surface warming from DLR so DLR fails to have any net thermal effect at the surface.
          The lapse rate slope determines the amount of convection needed to keep radiative energy in from space equal to radiative energy out to space and the lapse rate slope is set by the density gradient of atmospheric mass which results from gravity acting on total atmospheric mass. The more mass or the stronger the gravitational field the denser the air at the surface and the greater the proportion of incoming radiation that can be taken up by conduction and convection. Once that energy has been absorbed by the mass of the atmosphere it cannot be radiated out to space. Instead it is held as PE (not heat) in the molecules suspended off the surface and the higher those molecules the more PE they carry relative to KE.
          Density at the surface is critical to surface temperature because density determines the proportion of incoming radiation that can then be transferred to atmospheric mass by conduction and convection.
          The rate of decline of density with height is critical to the lapse rate slope because that rate of decline determines how much of the conduction from the surface to the lowest air molecules can then be moved further up by conduction.
          If anything other than mass density tries to alter the lapse rate slope then convection changes to neutralise it by changing the relationship between total energy involved in the ascent and total energy involved in the descent.
          If there are no radiative gases energy in the ascent equals energy in the descent.
          As one increases the radiative capability of the atmosphere then energy in the descent reduces relative to energy in the ascent to keerp surface temperature stable and the radiative balance with space stable.
          If the atmosphere were 100% radiatively efficient then all energy from the planet would leave to space from within the atmosphere and none from the surface but that can never happen as long as the gases comprising atmospheric mass can conduct and convect.
          Conduction and convection create a PE rerservoir within the atmosphere that is called upon (or not) as necessary to maintain thermal stability as long as insolation continues.
          Note that this only applies to gases and not liquids or solids hence the need for the Gas Laws.

      • … and, what does the Saharan surface know about the lapse rate? The 350 watts is hitting the surface. How can the surface avoid absorbing it?

  52. As a reference, you give “Estimation of Daylight Downward Longwave Atmospheric Irradiance under Clear-Sky
    and All-Sky Conditions”
    http://journals.ametsoc.org/doi/pdf/10.1175/JAM2503.1
    which claims

    Saturated water vapor pressure es was calculated by means of the Magnus expression (Guyot 1997)

    However, the provided equation is nonsense – it most definitely is NOT one of the Magnus equations. (There are several.) Here are 2 equations, one provided by the paper and the MagnusTetens equation.

    e_s = 6.107 * 10^(7.5*(T-273)/(508+T)) – paper

    e_s = 6.1078 * EXP(17.269388 * (T-273.16) / (T-35.86)) – MagnusTetens

    At 300K (88.33F), the paper’s equation gives a saturation vapor pressure of 10.9 mBar, and MagnusTetens gives 35.3 mBar – not even close!! Though there is no universally accepted formula to determine this, the correct value is somewhere between 35.2 and 35.4.
    Unfortunately, I have no way of determining if the paper has an error, or if the error is in Guyot 1997. However, either way, that paper should have never made it thru peer review!
    For details on about 30 formulas for calculating saturation vapor pressure, please see my web page. I also provide 2 programs (in a zip file) that you can use to help understand the problems.

    • Robert Clemenzi March 29, 2015 at 9:59 pm
      Interesting work!
      Maybe you might be interested in helping me with something, your line by line spectrum program, I’d like to take the measurement from my IR thermo which is calibrated to a BB with some emissivity that can be set. But I know that BB has a big spike from Co2 that needs to be added to get a more accurate flux, that Co2 “spike” should be able to be calculated by a program such as yours. An app that anyone could use that would take maybe air temp and the sky temp in IR and tell me how much more flux has to be added for Co2 along both natural and anthro. I think it would be beneficial to see how much IR is actually from Co2.
      If not, maybe you can point me to enough info that I could create it maybe from your analyzer.

      • micro6500, that is a difficult problem. None of the specs I’ve seen specify the frequencies used by IR thermometers. As a result, I just assume that they cover the entire spectrum, but that might be wrong. At any rate, using my line-by-line program, at 15C (59F), for a path of one meter, CO2 emits 2.37 W/m2 and water vapor at 60%RH emits 32.2 W/m2 with insignificant spectral band overlap. The blackbody emission for the same temperature is 390 W/m2. Therefore, for measuring the temperature of items only an inch or two away, these gasses are ignored.
        Of course, the CO2 and water vapor emissions are greater over longer distances. My program uses a default of 1,000 meters yielding 54.5 W/m2 for CO2 and 207.4 W/m2 from water vapor with about 20 W/m2 of spectral overlap.
        When pointing the thermometer toward the sky, I assume that an IR thermometer absorbs all the available IR radiation and indicates the temperature expected from a blackbody only one inch away. (The apparent or equivalent temperature, not the actual temperature.) As such, no “correction” is needed. To find an “actual” temperature, put the apparent temperature into the program and find the associated blackbody emission. (The program uses Stefan’s equation.) Then modify the temperature until the atmosphere emits the same amount. This will be very approximate, mainly because the temperature of the atmosphere changes in an unpredictable way with height.
        For example. if the IR thermometer reads 0C, that corresponds to a blackbody emitting 315 W/m2 with an emissivity of one. Using the program defaults, for 1km of atmosphere to emit the same power, its temperature must be 35C (95F) at 18%RH and 29C (84F) at 60%RH. If you change the assumed thickness to 2km, you will get 25C (77F) which is still a bit too high. However, if you change Alpha multiplier (on the Tools tab) from 200 to 20,000 (which makes the program way too slow) then the atmosphere temperature becomes 20C (68F) which is closer to what I observe. (Whether or not this large Alpha multiplier is really more accurate is beyond all the references I have access to.)

        • It has a 8-14u filter over the sensor. As for distance it has a 10:1 (iirc) distance to field ratio, since I can measure clouds my distance is pretty far.
          I’ll have to check your link out tomorrow. , thanks!

        • Robert Clemenzi commented

          using my line-by-line program, at 15C (59F), for a path of one meter, CO2 emits 2.37 W/m2 and water vapor at 60%RH emits 32.2 W/m2 with insignificant spectral band overlap. The blackbody emission for the same temperature is 390 W/m2. Therefore, for measuring the temperature of items only an inch or two away, these gasses are ignored.
          Of course, the CO2 and water vapor emissions are greater over longer distances. My program uses a default of 1,000 meters yielding 54.5 W/m2 for CO2 and 207.4 W/m2 from water vapor with about 20 W/m2 of spectral overlap.
          When pointing the thermometer toward the sky, I assume that an IR thermometer absorbs all the available IR radiation and indicates the temperature expected from a blackbody only one inch away. (The apparent or equivalent temperature, not the actual temperature.) As such, no “correction” is needed. To find an “actual” temperature, put the apparent temperature into the program and find the associated blackbody emission. (The program uses Stefan’s equation.) Then modify the temperature until the atmosphere emits the same amount. This will be very approximate, mainly because the temperature of the atmosphere changes in an unpredictable way with height.

          I think most of the hand help ones have a filter of 8u-14u, the open window in the atm, so mine seems pretty accurate from over 30′ away, and differences I attribute to changes in spot size with distance. I read your GHG paper, and I think you’re going the right way, but you need a IR thermometer like mine (plus then you’ll have a vested interest in the calculator I need), but you’re neglecting the heat in the ground, at night it(dirt, brick, concrete, asphalt) is warmer than the sky and air temps (clear day night cycle), grass however is colder that air temp.

          For example. if the IR thermometer reads 0C, that corresponds to a blackbody emitting 315 W/m2 with an emissivity of one. Using the program defaults, for 1km of atmosphere to emit the same power, its temperature must be 35C (95F) at 18%RH and 29C (84F) at 60%RH. If you change the assumed thickness to 2km, you will get 25C (77F) which is still a bit too high. However, if you change Alpha multiplier (on the Tools tab) from 200 to 20,000 (which makes the program way too slow) then the atmosphere temperature becomes 20C (68F) which is closer to what I observe. (Whether or not this large Alpha multiplier is really more accurate is beyond all the references I have access to.)

          I think when combined with surface temp data you could calibrate this. For instance you can measure the Tsky temp, see the rate of temp decrease, and something I’ve found is that when the rel humidity rising into the 80’s and 90% range (as the night cools) cooling slows down, even though the Tsky hasn’t changed. So the rate of cooling changes during the night, the cause of this should be able to be simulated. And there’s a lot of data that restricts the output.
          I was looking for the code you use to calculate the H2O and Co2 flux, but I couldn’t actually find it, can you point me to what I’m looking for?
          BTW, I have lots of surface data that you would find useful. I’m looking at the rate of change by day, by year, and by area on temps, and part of that is the forcing, I’m adding solar forcing for each station to my code now, I figure I have what was at toa prior to albedo changes, and I can see what the temps do, should be interesting, then if I can add co2 and h2o to the mix based on air temp and forcing, sound like something to learn.
          here: http://sourceforge.net/projects/gsod-rpts/

      • If you had better data, I think you would find that the ground cools much faster than the atmosphere. Unfortunately, you will need balloons to personally collect that data, or you can get the data online.
        I have written a Lapse Rate Animation program that plots a year’s worth of data in a way that helps to understand the reality. I strongly suggest looking at the SouthPole data. (Notice that the actual SouthPole data differs from what the text books say!)
        BTW, I like your sourceforge plots.

        • @Robert Clemenzi
          When I say air, I’m meaning 2 meters, since you mentioned balloons, that air temp goes down and then up.
          But, when we’re told of catastrophe, the only reason they would talk about the troposphere is because the surface isn’t behaving.
          But if you measure the temp of a concrete sidewalk, or the dirt between patio bricks and the air above it, or the grass besides it right before Sun up, it’s still warmer than both (at least is has been for me). Maybe with short days, it might get non-linear.
          Michael 2 commented

          Up a ways you asked about how air gives up heat when it cannot emit infrared. Gases such as nitrogen give up energy by physical contact to molecules of carbon dioxide, methane or water which CAN then emit infrared. In this sense, more carbon dioxide improves “top of atmosphere” cooling by becoming a more effective radiator, but it also retains more heat at the surface. This increases the vertical gradient which in turn would usually provoke more convection.

          This is both where I was coming from (that physical contact would normalize molecular temps and my IR thermometer could detect it) and where I’m going(that the bulk of the atm doesn’t actually cool by itself).
          But it explains the various bits of data I have and, I was going to say trust, but understand might be a better word.
          But we have a pretty detailed log of the response to the days solar energy as it changes through out the year.

      • micro6500 says

        the only reason they would talk about the troposphere is because the surface isn’t behaving.

        No, they look at the troposphere because their theory says to. However, their theory has a serious error which explains why their predictions will never come true.
        I am a bit confused by the rest of your post – too many pronouns. Basically, in the morning the ground is significantly colder than the air a hundred meters above it when measured with a thermometer (assuming no wind). Two meters is not high enough to be above the morning “fog” layer which limits how cold the ground can become.
        BTW, the *ground* temperature may be +/-20C (and sometimes more) with respect to 2 meters above the ground.

        • Robert Clemenzi commented.

          Basically, in the morning the ground is significantly colder than the air a hundred meters above it when measured with a thermometer (assuming no wind). Two meters is not high enough to be above the morning “fog” layer which limits how cold the ground can become.
          BTW, the *ground* temperature may be +/-20C (and sometimes more) with respect to 2 meters above the ground.

          I’ve only measured it colder in the pre-dawn morning, and warmer in the late afternoon.
          You can see this “fog” reduce night time cooling, but only when rel humidity goes over ~80%, until then cooling rates are much higher.

    • I finally found a reference to the important parts of Guyot 1997 – on page 142

      T is expressed in degrees-C.
      Among the most commonly used formulae is that of Magnus
      e(T) = 6.1070 * 10^(7.45T/(235+T)) (3.12)

      If that equation is converted to Kelvin, then it should be

      e(T) = 6.1070 * 10^(7.45(T-273.16)/(235-273.16+T)
      e(T) = 6.1070 * 10^(7.45(T-273.16)/(T-38.16)

      From this it is pretty obvious that someone added when …

      235 + 273.16 = 508.16

      To be clear, the text book is nearly correct, but the paper .. it passed peer review and therefore qualifies as “climate science”. In addition, there are at least 12 references to it.

    • Hardware store infrared thermometers are sensitive to infrared in the “atmospheric window” meaning they are completely insensitive to carbon dioxide and apparently also water vapor. They do see the emission of liquid water droplets in clouds. This is easily demonstrated by point it at anything more than a few meters away, especially the clouds at night. If they were seeing CO2 you’d have a nearly uniform temperature measurement but mine goes to max-negative, -60 F, on a clear sky but typically +21 or so for clouds.

      • Michael2, that is like mine, 8-14u but water does show up there.
        But when you measure -60F, that is the temp of that window to the surface. The full spectrum IR (pyrometers iirc) get more water, Co2 and the rest of the long wave IR and can make up for that, but I still point to that you can make ice on a clear dry night without air temps going below 32F.

    • Robert Clemenzi
      I was thinking about the temp vs altitude chart, In relationship to the surface being warm compared to ground level air most of the year (at least locally), that the chart showing temps dropping as altitude goes up would be how the IR from the ground would penetrate surface air, brightly near the ground, and it would be attenuated by GHG’s over distance (up).
      Now I understand (if I understand this at all) Co2 blocks all IR in far shorter distances than the minimum temp altitude, but I still thought it striking, and something I should say out loud, if nothing more than to plant a seed.
      http://mc-computing.com/Science_Facts/Lapse_Rate/Lapse_Rate_Summer.html

  53. Joeldshore, it might help you to remember the scientific question here. It is not incumbent upon the skeptics to knock your nonsense into a cocked hat, it is the burden of “your side” to falsify the null hypothesis with respect to climate change, i.e. nothing is happening that lies outside the parameters of natural variability.
    Please locate and quantify the weather events you imagine lie outside the realm of our historical data set?
    Until the AGW mob can satisfy that most basic of scientific principles, the null hypothesis holds, no?

    • Thank you Larry. When today’s wriggles are still within past natural variability, anything said about today cannot be significant. Period. End of statistical lesson. And please Joel, do not be showing spliced temperature reconstructions with modern observations to demonstrate alarming conditions. Apples and oranges. The fine scale of today, measured by averaging fine scale daily observations, cannot be captured in the reconstructions which do not use daily averaged observations.
      And now a question. How is relative and absolute humidity at different atmospheric levels, collected and reported? Curious. Directly observed or calculated?

      • Pamela, NOAA uses balloons to measure the temperature and humidity at various altitudes. For high precision, humidity is determined using a chilled mirror to determine the local dew point which is converted to relative humidity using a model (an equation). As a cheaper alternative, they could use a calibrated humidity sensor. Since “the science is done”, I was surprised to find over 30 models (equations) to make the conversion.

  54. Today myself and my good lady have been riding our harley in out back oz , it has an ambient temp gauge, we had the odd cloud that gave maybe a quarter of a mile shadow, every time in shadow the air temp dropped up to two degrees c. Strange that the temp drops so quickly with a sun shade.

  55. I wish your comments weren’t closed on the Norwegian lifespan vs sunspot article but you might have some interesting data that would perhaps yield interesting results twisted a different way.
    I ran some analysis on my own Norwegian ancestors and turned up an interesting thing — summer-born Norwegians have a lifespan distribution that peaks at 75 years of age (bins spaced 5 years apart) whereas winter born Norwegians had two peaks, one at 65 and another at 75. In other words it seems to matter what month of the year you were born as to lifespan.

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