Guest Post by Willis Eschenbach
In my last post I investigated the mathematical relationship between the amount of total precipitable water vapor (TPW) in the atmosphere, and the clear-sky greenhouse effect. Here is the main figure from that post showing the relationship:
Figure 1. Scatterplot, TPW (horizontal scale) versus Atmospheric Absorption (vertical scale). Dashed yellow line shows theoretical value based on TPW. Dashed vertical line shows area-weighted global average value. Dotted vertical lines show the range of the global average value over the period. The slope of the curve at any point is 62.8/TPW (W/m2 per degree)
In this post I’m looking at the other half of the relationship. The other half is the relationship between the ocean surface temperature and the total precipitable water. The good news is that unlike the CERES data which is only about 15 years, we have TPW records since 1988 and sea surface temperature for the period as well. Figure 2 shows the relationship between the two:
Figure 2. Scatterplot, RSS total precipitable water (TPW) versus the ReynoldsOI surface temperature data. See end notes for data sources
As you can see, the relationship is regular but not simple. I first thought that the relationship was logarithmic, but it turns out not to be so. It is also very poorly represented by a power function. After unsuccessfully investigating a variety of curves, I found it could be approximated by an inverse sigmoid function (shown in yellow above). Now, given the number of very smart folks here, I suspect someone will be able to give a physical reason complete with the right equation, but this one suffices for my purposes.
Now, the relationship between water vapor and atmospheric absorption is clearly logarithmic, as is predicted by theory. On the other hand, I don’t know of any simple theory relating SST to total precipitable water. For example, the curve doesn’t match the Clausius-Clapeyron increase in water vapor. And clearly, my method is purely heuristic and brute-force … but that’s OK because I’m not claiming that it is explanatory. My purpose in doing it is quite different—I want to figure out how much change there is in the precipitable water per degree of change in the sea surface temperature (SST). And for that, the main quality is that the function needs to be differentiable.
So let me recap where we stand. In the last post I derived a mathematical relationship between the two variables shown in Figure 1. Those are clear-sky atmospheric absorption of upwelling longwave radiation from the surface, and the total precipitable water content (TPW) of the atmosphere.
And above in this post, I’ve derived a mathematical relationship between the two variables shown in Figure 2. Those are the total precipitable water content (TPW) of the atmosphere, and the sea surface temperature (SST).
That means that by substituting the latter into the former, I can derive a mathematical relationship between the SST and the atmospheric absorption.
Of course I wanted to ground-test my formula that converts from sea surface temperature to atmospheric absorption. I only have the CERES data for the absorption, so this covers a shorter period than that shown in Figure 2. Since the overall relationship was established using the Reynolds sea surface temperature data, I used that for the comparison.
Figure 3. Atmospheric absorption of upwelling longwave radiation versus sea-surface temperature. See end notes for mathematical derivation.
Dang, I’m pretty satisfied with that as a comparison of theoretical and observed atmospheric absorption. A few comments. First, the difference below 0°C is because CERES and Reynolds are measuring slightly different things below freezing, when there is ice in the picture. CERES is measuring the average temperature of the ice and the water, and Reynolds is measuring water temperature alone.
Next, the slight bend in the black line from 0°C to 25°C is not completely captured by the red line. This is because I’ve included the data below freezing, which has slightly distorted the results. Probably should have left it out, but I figured for completeness …
Next, the slight bend in the black line from 0°C to 25°C is due to the fact that surface radiation is proportional to the fourth power of the temperature. If absorption were calculated against surface upwelling radiation rather than temperature, it would plot as a straight line … go figure. I’ve done it this way because there is much discussion about the value of the “water vapor radiative feedback” which is measured per degree C. I could get a slightly closer fit by including the T^4 relationship, but my conclusion was that the gain wasn’t worth the pain … if I need greater accuracy I can redo the figure, but it is more than adequate for the present purposes.
The amount of the feedback is calculated as the slope of the red line in Figure 3. The slope is the change in the absorption for a 1°C change in the sea surface temperature. Figure 4 shows the amplitude of the water vapor radiative feedback across the range of ocean temperatures:
Figure 4. Water vapor radiative feedback, calculated as the change in atmospheric absorption of upwelling longwave radiation per 1°C change in surface temperature.
That is a very interesting shape. Now, given the general shapes of Figure 1 and Figure 2, I might have expected the shape … but it came as a surprise anyhow. Over much of the world, the two tendencies cancel each other out and the clear-sky water vapor radiative feedback is about 3-4 W/m2 per degree C. But in the tropics, where the water is warm, the water vapor feedback goes through the roof.
DISCUSSION
So … with such a large radiative feedback from water vapor, three to four watts per square metre per degree and much higher in the tropics, why is there not runaway feedback? I mean, the so-called “climate sensitivity” claimed by the IPCC says that 2-3 W/m2 of additional radiation will cause one degree of warming. And according to observations above, when it warms one degree, we get additional downwelling radiation from water vapor of 3-4 W/m2. And that amount is claimed to be sufficient to warm it more than one additional degree … a recipe for runaway positive feedback if I ever saw one. So … with that large a radiative feedback, why isn’t there runaway feedback?
Well, you might start by perusing Dr. Roy Spencer’s discussion of the subject, yclept Five Reasons Why Water Vapor Feedback Might Not Be Positive. The TL;DR version is that as the amount of water vapor in the air increases, downwelling radiation does indeed increase … but there are plenty of other things that change as well.
To expand a bit on one of the things Dr. Roy mentioned, in his discussion of evaporation versus precipitation he said:
While we know that evaporation increases with temperature, we don’t know very much about how the efficiency of precipitation systems changes with temperature.
The latter process is much more complex than surface evaporation (see Renno et al., 1994), and it is not at all clear that climate models behave realistically in this regard.
Let me add a bit to that. Rainfall goes up with increasing atmospheric water as shown in Figure 5:
Figure 5. Scatterplot, rainfall evaporative cooling versus total precipitable water. TRMM data only covers latitudes 40°N to 40°S.
Note the size of the cooling involved … not watts per square metre, but hundreds of watts per square metre. As precipitable water goes from about forty to fifty-five kg per square metre, evaporative cooling goes from fifty to two hundred fifty watts per square metre or more … that’s a serious amount of cooling, about ten watts of additional cooling per additional kg of precipitable water.
We can compare that to the slope of increasing water vapor radiative feedback in Figure 1. The slope in Figure 1 is 62.8 W/m2 divided by TPW, so at a TPW of 50 kg/m2 that would be about 1.2 W/m2 of additional radiative warming per additional kg/m2 of water … versus 10 W/m2 of rainfall evaporative cooling per additional kg/m2 of water.
But wait … there’s more. Figure 6 shows the rainfall evaporative cooling versus sea surface temperature (SST). Since SST and precipitable water are closely related, Figure 6 is quite similar to Figure 5.
Figure 6. Scatterplot, rainfall evaporative cooling versus Reynolds sea surface temperature.
As in Figure 5, at the hot (right hand) end of the scale, the rainfall evaporative cooling goes from about 50 to about 200 W/m2 very quickly. However, in this case it makes that change as the SST goes from about 27° to 30°. And that gives us a net cooling of about 50 W/m2 per degree … kinda dwarfs the 3-4 W/m2 per degree of water vapor based warming …
There is another interesting aspect of Figure 6 … the empty area at the lower right. I have long stated that the thermoregulatory phenomena like thunderstorms are based on temperature thresholds. The blank area in the lower right corner of Figure 6 shows that above a certain sea surface temperature … it’s gonna rain and cool it down. And not only will it rain, but the hotter it gets, the greater the rainfall evaporative cooling overall, and the greater the minimum evaporative cooling as well.
Nor do the cooling effects of water vapor end there. Increasing water vapor also increases the amount of solar energy absorbed as it comes through the atmosphere. As with the absorption of the upwelling longwave, the relationship is logarithmic. Figure 7 shows that relationship.
Figure 7. Scatterplot, atmospheric absorption of downwelling solar radiation (vertical axis) versus total precipitable water (horizontal axis)
Logarithmic relationships of the form “m log(x) + b” have a simple slope, which is m / x. The slope of the equation shown in Figure 7 is 31.6/TPW (W/m2 per degree). Now, earlier we saw that the slope of the warming from increasing water was 62.8/TPW (W/m2 per degree). This means that at any point, half of the warming due to water vapor radiative feed back is cancelled out by the loss in downwelling sunlight due to increased water vapor.
Nor is this the end of the related phenomena … Figure 8 shows the correlation between total precipitable water and cloud albedo:
Figure 8. Correlation of total precipitable water (TPW) and cloud albedo.
As you can see, over much of the tropics, as precipitable water increases so does the cloud albedo (red-yellow). Makes sense, more water in the air means more clouds. Again, this has a cooling effect.
Nor is this an exhaustive list, I haven’t discussed changes in downwelling longwave radiation due to clouds … the relationships go on.
FINAL THOUGHTS
The center of climate action is the tropics. Half of the available sunlight strikes the earth between 23° north and south. The main phenomena regulating the amount of incoming solar energy occur in the tropics. And as the graphs above show, the amount of water in the atmosphere is at the heart of those phenomena.
So … is the feedback of water vapor positive or negative? Overall, I’d have to say it is well negative, for two reasons. The first is the long-term stability of the global climate system (e.g. global surface temperature only changed ± 0.3° over the entire 20th century). This implies negative rather than positive feedback.
The second reason I’d say it’s negative is the relative sizes of the various feedbacks above. These are dominated by the evaporative cooling due to rainfall and by the changes in reflected sunlight due to albedo, both of which are much larger than the 3-4 W/m2 in increased water vapor radiative warming.
However, there is a very large difficulty in isolating the so-called “water vapor feedback” from the myriad of other phenomena. This difficulty is embodied in what I refer to as my “First Rule Of Climate”, which states:
In the climate system, everything is connected to everything else … which is turn is connected to everything else … except when it isn’t.
For example, the temperature affects the water vapor – when the temperature goes up, the water vapor goes up. When the water vapor goes up, clouds and rain go up. When clouds and rain go up, temperatures go down. When temperatures go down, water vapor goes down … you can see the problem. Rather than having things which are clearly cause and clearly effect, the whole system is what I describe as a “circular chain of effects”, wherein there is no clear cause and no clear boundaries.
Anyhow, those are the insights that I got from examining the total precipitable water dataset … like I said, no telling where a new dataset will take me.
And speaking of precipitable water, it is sunset here on our hillside. As I look out the kitchen window towards the ocean I see the fog washing in from the Pacific. It is pouring in waves over the far hills, swallowing redwood trees as it rolls on toward our house … it came and visited last night as well.
I love that sea fog. It reeks of my beloved ocean, with the smell of fishing boats and slumbering clams, of hidden coves and youthful dreams. And when the fog comes in, it brings with it the sound of the foghorn at the mouth of Bodega Bay. It’s about seven miles (ten kilometres) from my house to the bay, but the sound seems to get trapped in the fog layer, and when the fog comes I hear that foghorn calling to me in the far distance, a mournful midnight wail. I took frequent breaks from my scientific research and writing last night to sit outside on a bench, where I let the fog wreathe around my head and bear me away. I breathe in the precipitated water, and I emerged refreshed …
My best to everyone, and for each of you, I wish for whatever fog it is that carries you away in reverie and washes off the mask of socialization …
w.
REQUESTS
My Usual Request: Misunderstandings suck, but we can avoid them by being specific about our disagreements. If you disagree with me or anyone, please quote the exact words you disagree with, so we can all understand the exact nature of your objections. I can defend my own words. I cannot defend someone else’s interpretation of some unidentified words of mine.
My Other Request: If you believe that e.g. I’m using the wrong method or the wrong dataset, please educate me and others by demonstrating the proper use of the right method or identifying the right dataset. Simply claiming I’m wrong about methods or data doesn’t advance the discussion unless you can point us to the right way to do it.
NOTES
The math … I start with the equation for relationship between absorption (A) and total precipitable water (TPW) shown in Figure 1:
A = 62.8 Log(TPW) – 60
To this I add the inverse sinusoidal relationship between TPW and sea surface temperature, as shown in Figure 2:
TPW = – 13.5 Log[-1 + 1/(0.00368 SST + .887)] -19.1
Combining the two gives us:
A = 62.8 Log[-19.1 – 13.5 Log[-1 + 1/(0.887 + 0.00368 SST)]] – 60
Differentiating with respect to sea surface temperature gives the result as shown in Figure 3:
dA/dT = 3.13/((-1 + 1/(0.887 + 0.00368 SST)) (0.887 + 0.00368 SST)^2 (-19.1 – 13.5 Log[-1 + 1/(0.887 + 0.00368 SST)]))
Further Reading: NASA says water vapor feedback is only 1.1 W/m2 per degree C …
DATA
Reynolds SST data, NetCDF file at the bottom of the page
TRMM data, NetCDF file at the bottom of the page
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Willis;
Just below Fig 7, it appears a portion of your post is cut off at the following sentence:
“This means that at any point…”
Thanks, fixed.
w.
hey Willis:-)
they said ….the fog wasnt fogging n the redwoods were going to dry n die..
just sayin:-) lol
another educational post thanks;-)
Speaking of figure 7, isn’t that relationship also somewhat controlled by the amount of down-welling sunlight in the first place. The tropics happen to have the highest TPW and 50% of the sunlight entering the atmosphere. The circular chain of effects is complicated indeed. Nice post.
The wateer vapor feedback looks negative, but if climate is governed by chaotic rules, there is still a possibility it will bite your understanding on its metaphoric ass.
United Nations got a really fleshy behind – which might become severely bitten by natural variability.
Thank you. This looks impressive at the first look. It is a well written story connecting a solid theory of the complex adaptive climate system to empirical data.
The conclusion that the earth has a natural thermostat, a kind of a heat pipe system that we have in our computers, is plausibly explained.
The first question for the peer reviewers here: what is missing? Ice, ocean currents ? Are they important?
GC and Eschenbach,
For a given water or air temperature, evaporation will increase with wind speed. Also, air temperature plays a more important role than SST for evaporation. That is, if hot air is blowing off land onto the ocean, evaporation will be higher than if the air temperature over the water was in equilibrium with the SST because evaporation is a surface phenomenon rather than a bulk process.
If you oxidise hydrocarbons, you get at least CO2 and H2O.
If you oxidise a few gigatonnes of hydrocarbons you get a fair amount of water.
I suppose it all eventually precipitates out.
All very tricky.
Cheers.
Mike Flynn — yes indeed. For fun I calculated the amount of water released by fossil fuel burning a couple of years ago. My estimate (amateurish) was 116 cubic miles, or about the volume of Lake Erie. Anybody wanting to try this should start here: http://cdiac.ornl.gov/
Dan
I should clarify, this was over the historical period 1751-2013.
Dan
So. That’s why the sea level is rising! 😉
I think there is an error in the discussion after Fig. 7. It states that “This means that at any point, half of the warming due to water vapor radiative feed back is cancelled out by the loss in downwelling sunlight due to increased water vapour.” Surely it is the opposite – the feedback effect of water vapour is increased since (a) it absorbs downwelling visible light and (b) it absorbs upwelling long wavelength light. These effects both increase the amount of energy absorbed by the atmosphere and so add to the heating effect of water vapour.
There is also an error when discussing the effects of evaporative cooling. This should be regarded as a way to move heat and energy around from one point on the globe to another. It does not change the total energy of the atmosphere/ocean system and so won’t actually cause any cooling
on average. There will be a slight effect since the heat is effectively moved to the atmosphere where it can radiate away more efficiently than at the surface but I am guessing that this value is not what is plotted in Fig. 5
G,
you seem to be confusing visible water vapor in the air column (clouds) with invisible (to sw radiation) humid air.
clouds are the bugaboo in the Climate charlatans junk model outputs.
Hi Joel,
I don’t think so. Fig 7 is the absorption of water vapour for downwelling visible light. So water vapour firstly absorbs 50 to 100 W/m^2 of visible light from the sun as it enters the atmosphere and before it reaches the surface. Then of the long wavelength light emitted by the surface it absorbs another 3 W/m^2. So the
total additional absorption from water vapour in the atmosphere is the sum of the two not the difference. This has nothing to do with clouds which reflect
visible light and so would not show up in a measure of absorption but which are a negative feedback (and one that is explicitly not discussed in this post since it talks about clear sky effects).
By visible water, you are referring to droplets (liquid water), not water vapor (gas).
I think if solar radiation is absorbed in the atmosphere instead of at the surface it is more easily (more quickly) lost to space since it is radiated equally in all directions.
Craig, I would like to add one more thought for consideration to this. What you say appears logical and certainly atmospheric convection would change, likely accelerating. There is another factor in addition.
With an increase of water vapor, even in clear sky situations, s/w and overall insolation to earth’s longest residence time energy holder decreases. Of course this decrease is very substantial once clouds form, but it is non trivial even in clear sky conditions. Earth’s longest holder of energy is neither the atmosphere or the land, but the S/w selective oceans. Because this is the longest residence time of all energy entering the earth, (up to millennial scale) flux in this input and output can have a far greater affect, over time, of the amount of total energy in the system.
Alas, we are a long ways from seeing this chartered as we do not know the residence time of disparate insolation entering the oceans.
Willis, if still reading this, I welcome your thoughts.
An excellent and very interesting piece – thank you so much for having an enquiring mind and sharing it all with us.
Among other things I was stunned by the magnitude of the rainfall evaporative cooling.
I was also stunned by the curve forms. Steep curves tend to create high sensitivities and a correspondingly huge uncertainty in estimation of a dependent variable.
The belief that Climate models are capable to get the net global energy balance right within 1 W/m^2, or something like that, is far beyond my belief. (the Earth´s energy imbalance is in the order of magnitude 0,6 W/m^2).
“circular chain of effects”
I would say it as, “A tightly-coupled, complex system with emergent properties.”
Willis, your plots showing asymptotic behavior as SST approaches 30degC is why James Hansen was smoking good dope and selling lies when he opined the seas would boil with enough CO2.
Overall feedback of water in the climate system is strongly negative. Anyone (including the IPCC and GCM climate model charlatans) who says otherwise are selling an agenda, not science based on natural, observed phenomenon.
It is not quite that simple. The asymptotic behaviour depends on the temperature of the atmosphere which determines how much water vapour can be supported by the air column before it saturates and it starts raining. The warmer the atmosphere the more water vapour it can support and so the more the asymptote moves towards higher temperatures. The current graphs are really for relatively constant atmospheric temperatures and varying ocean temperatures. They do not say what will happen if the atmosphere heats up as well.
Geronimo July 28, 2016 at 11:56 pm
“The current graphs are really for relatively constant atmospheric temperatures and varying ocean temperatures.”
Huh? I don’t understand this. The data points are 1°x1° gridcell averages, and each gridcell most definitely has variations in both atmospheric and ocean temperatures.
Regards,
w.
Geronimo
July 28, 2016 at 11:56 pm : What you have been doing is deliberate twisting. The figures show what we knew to be the CAGW breakpoint. Where the water takes over and controls actual increased solar input as it occurs. You should be able to see and read here how any feedback, real or imagined, is swamped at an increasing rate by evaporative uplift of energy to space. Maybe you cannot understand the scale of it. but be thankful for what makes your existence possible.
Except humidifying air cools it. Google psychrometrics…
Willis there is a lovely kernel of information/proof hidden in the middle of your discussion above. You might remember that we discussed why the incoming 341 W of radiation (average) hitting the sea only produced 80 W of evaporation (average). I speculated at the time (logical guess) that it did not reach the water because of the saturation of the air right next to the water surface, meaning that a large % of the incoming radiation was absorbed and tossed back before reaching the surface. Some hits the surface to produce evaporation and some passes into the water providing illumination and warming.
Your evaporative cooling chart provides insight into this simplistic guess of mine. The answer is not that a certain amount of energy reaches the surface but that the answer is a formula, not a number. When the sea surface temperature rises past 25 C the evaporation rate ramps up rapidly. I attribute this to the heat available just above the surface that, when the sea is cool, doesn’t add much to evaporation. But above 25 that heat, trapped by the water vapour close to the surface, starts to reach the skin and drives additional evaporation. Maybe.
In short I wasn’t all that wrong and that the evaporative cooling rising to the hundreds of Watts per Sq m supplies the detail explaining why the average is only 80 W. It is because most of the oceans are far cooler and contribute far less to the total mass evaporated.
Locally evaporated water vapour moves away, messing up the chart a bit, but the principle remains. the % of incoming radiation that reaches the water surface must change rapidly above a surface temperature of 25C. Otherwise it could not drive a cooling rate of a few hundred W when it is only 8 w over a very cold ocean. The mechanism that takes the heat absorbed in the air just above the water might be radiative transfer or convective flow from wind. Whatever it is, it kicks in big time above warm oceans that exceed 25C.
Alternatively, the “average” of 80 W could be the problem – we are asked the wrong question. In the data above one can show that sometimes the incoming radiation is 341 W and the cooling is 261 W the difference goes into warming the water, not evaporating the surface. 261 is not 80 so thinking about the global “average” is misdirection. Your curves show clearly that as the water temperature rises the evaporation mechanism mysteriously becomes much more efficient, whether it is cloudy or not.
Clean water in a very smooth container boils at a much higher temperature than the same water in a rough container. Perhaps there is a water evaporating equivalent of cloud condensation nuclei that kicks in more vigorously above 20-25 degrees, and that the nature of sea water (filled with impurities) permits/assists the evaporative cooling profile.
Crispin in Waterloo July 29, 2016 at 12:19 am
Crispin, this reanimation of your desperately dogged attempt to convince people that downwelling longwave radiation is somehow not actually absorbed by the ocean is as incorrect now as it was when you first proposed it. I’m not going to argue well-established physics with you, this is neither the thread nor the site for that.
And no, there is no way that the downwelling longwave is “absorbed and tossed back” just microns above the surface as you seem to think. Downwelling IR is absorbed by the ocean. Why is that so hard for you to accept? If the downwelling IR were not absorbed by the ocean, the ocean would have frozen eons ago.
Look, I know that you truly believe all those things, but the only folks who agree with you are wearing tinfoil hats. I can’t say this clearly enough. You are putting hand-waving pseudo-explanations out there as if they were valid science, and they’re not.
Now, I know I should sugar-coat all of this to make it more palatable, but there is no easy way to tell a man he’s talking impossibilities.
It puts me in mind of the Corporal who calls a Private in and says to him “Son, I just got the news that your mother died”. The Private breaks down completely because of the sudden shock, weeping and wailing.
The Sergeant says to the Corporal, “You need to learn to do that correctly if you want to be a leader. You should break bad news gently to your men!”. The Corporal asks him how to do that. The Sergeant says “Suppose you hear a man’s favorite cat died, his favorite pet. You might first say ‘I heard that your cat got stuck up a tree.’ Then the next day you might say ‘They still haven’t been able to rescue your cat’. Then on the third day, when he’s prepared, you give him the bad news.”
“I understand, Sergeant, give them time to absorb it”, said the Corporal.
So the next time the mother of one of the recruits died, the Corporal called him in and said to him,
“Private Jones, I have some bad news for you. Your mother got stuck up in a tree …”
Anyhow, Crispin, what I’m trying to say is that your science got stuck up in a tree.
Regards,
w.
PS—I also don’t understand your claim that downwelling longwave radiation causes “illumination and warming” when it is absorbed by the ocean. Warming I get, but illumination?
Well, for those of us in the animal kingdom that can see in the infrared ….
Willis
I read your whole reply. I am surprised by some of the things you don’t get.
You object to my statement that not all the IR makes it to the ocean surface then launch into a humorous lampooning of the author’s tin foil hat mental state. Mine.
So, let’s look at your article. You mention in your piece that water vapour in the column intercepts some of the incoming radiation and then when the water mass total rises to, for example, 50 kg per Sq m, there is a significant rejection, by re-radiation upwards, of some of it. You even explained that as the water vapour mass increases, the effect increases.
This is literally identical to ‘my science’ as you characterise it. Absolutely the same effect.
I am more interested in understanding what is happening than lampooning you in witty reply, despite the many hooks you proffer. Listen to your mother, drop the ‘something extra’.
You obviously accept the mechanism because you describe it well and provide supporting evidence that not all the incoming radiation makes it to the surface. I pointed out that as the distance from the ocean surface becomes very small, the absolute humidity is very high and it’s interception efficiency rises proportionately (at the relevant wavelengths). The intercepted energy, absorbed by the water vapour just above the water surface, heats the vapour, bringing up the temperature at least near ambient. This helps transport it away from the surface and more evaporation takes place. That intercepted energy never makes it to the ocean surface in exactly the same way it doesn’t penetrate the water column, as you clearly explained.
I was reminding you of our earlier conversation, highlighting the mechanism and its increased effect as the humidity rises. It seems you have some around to my view, albeit by another path of investigation.
I also said that directly above the ocean surface there is a layer of air, very thin, that is supersaturated. You doubted that at the time. Well, physical phenomena are what they are. Incoming knowledge can also be absorbed and rejected. The interception of radiation at that point explains in part why air blowing off the ocean is not 1 degree C.
Light:
Part of the radiation that does make it to the surface is visible light. That is why if you go scuba diving the water around you is illuminated. Most of that energy is absorbed by the water, some makes it out again, which is why you can look into the water and see the coral (etc).
Easy now, “downwelling IR” from water covers a broad area of the spectrum. This is what Modtran “sees” in the water bands from the surface looking up:
Note the extremely large range of blackbody temperatures (altitudes) across the spectrum of deviation from surface temperature (300K).
We are talking about a range from WN 600 to 1300 and the ocean surface can be expected to absorb differently across this range.
Remember also that atmospheric water is a very efficient absorber of incoming solar radiation.
Seemingly a portion of this would be kinetically converted to “downwelling” IR much in the way the surface converts it to “upwelling IR”.
Crispin in Waterloo July 29, 2016 at 7:24 am
Crispin, thanks for your reply. I said that a column of air ~20 km tall can absorb a significant amount of downwelling infrared.
You have claimed some mythical 20 mm or 20 cm or so thick layer of saturated air just above the ocean can do the same thing … no matter how saturated the air is, there simply aren’t enough water molecules in a thin layer to absorb much of anything.
Rather than speculating about the numbers, I turned to MODTRAN calculate the per-metre absorption of longwave. The actual shape of the graph of the per-metre absorption is quite interesting. Absorption peaks at about 1.5 km, at an absorption rate of 0.019 W/m2 per metre of depth. So let’s suppose for the sake of argument that your one-metre-thick layer of supersaturated air can absorb at a rate of ten times the maximum absorption observed in the normal air column …
…
… that’s still only an absorption of two-tenths of one W/m2, an amount that is lost in the noise.
Next, you seem to think that the air right next to the surface can absorb lots more water or become supersaturated in some manner … but in fact, air immediately over the ocean is typically already pretty highly saturated with water vapor. Average air around the TAO buoys, for example, runs at about eighty percent relative humidity (95%CI = 68%RH to 95% RH, so it physically cannot absorb much more water. (Not that it would matter, even at an RH of 100% a one-metre thick layer of air is still far too thin to do what you claim.)
Yes, you are calling on identical scientific principles … but you are totally neglecting the physical situation. A layer of the atmosphere one metre thick will not absorb a significant fraction of downwelling IR, regardless of its composition.
Best regards,
w.
Crispin:
Your observation about what might happen to DLWIR has merit. But there’s little hope of convincing anyone totally clueless about the existence of the Knudsen layer and the nearly total absorption of remaining DWLIR by the microns-thin surface skin of the ocean. Physical oceanography is not Willis’ field.
Thanks for a very interesting article … as usual 🙂 !
Very interesting post, thank you!
What is this Warmist obsession with ‘radiation’…downwelling, upwelling or otherwise?
The important thing about water vapour is that it PHYSICALLY TRANSPORTS heat.
Any other measurements you take are dwarfed by this property.
charles nelson July 29, 2016 at 1:10 am
Thanks, Charles. To use your terms, about 80 W/m2 of energy is PHYSICALLY TRANSPORTED as latent heat, that is to say as water vapor, from the surface to the atmosphere. Another 20 W/m2 of energy or so is PHYSICALLY TRANSPORTED as sensible heat, that is to say as air directly warmed by contact with the surface.
By contrast, the surface is constantly radiating about 390 W/m2 upwards, some of which is absorbed by the atmosphere and clouds and a smaller portion of which goes directly to space.
So no, radiation is not “dwarfed” by the physical transport of latent and sensible heat. Instead, the energy radiated away by the surface is about four times the size of the total surface energy loss in the form of latent and sensible heat.
And going the other way, the energy entering the surface is almost entirely radiation, about 170 W/m2 of solar and about 330 W/m2 of longwave …
Finally, the energy transport into and out of the planet is entirely radiative, with shortwave entering the planet and longwave leaving.
That’s why people discuss radiation … because it is important in the overall scheme of things.
However, you’ll notice that I have included the cooling effect of rainfall driven evaporation, so by no means am I ignoring direct transport of energy.
Regards
w.
And how much energy is transported as latent heat into the warmest areas of the globe?
Willis…heat energy (as latent heat is PHYSICALLY) transported into regions of polar darkness in WINTER where there is not much in the way of incoming radiation taking place at all!
Also rapidly rising warm moist air over equatorial oceans PHYSICALLY carries vast amounts of physical heat high into the atmosphere where it seems to have no problem cooling.
I just checked the satellite data a few moments ago and the surface temperature over the equatorial pacific ocean is around 30˚C…the tops of the cloud band in the same area are around minus 60˚C.
Willis,
“Finally, the energy transport into and out of the planet is entirely radiative, with shortwave entering the planet and longwave leaving.”
By “planet” I assume you mean the earth and its atmosphere. This is a very important point because it implies that evaporative does not cause overall atmosphere to lose heat.
Water evaporates from the surface, then rises (in part because water vapor is lighter than air), then cools, then condenses. The latent heat of condensation (warming) is equal to the latent heat of evaporation (cooling) and there is no heat lost or gained by the overall atmosphere.
Evaporative cooling does not remove heat from the earth/atmosphere system, only radiation can do that.
Water vapor molecules absorbs some of the incoming long-wave radiation and some of the outgoing long-wave radiation. Then they re-radiate a portion of the absorbed radiation to the surface, which keeps the surface warmer than it would otherwise be.
If the water vapor feedback were positive without limit, the earth would much warmer and wetter than it is today. Sunlight would cause evaporation, which would enhance the greenhouse effect, so more evaporation would occur, so the greenhouse effect would be amplified, so more evaporation would occur, etc. But this is not the entire effect. Water vapor also condenses to form clouds, which reflects incoming solar radiation and that keeps the planet cooler than it would otherwise be.
Condensation also places an upper limit on the amount of water vapor that can accumulate in the air. Water is returned to the surface as precipitation from clouds or the dew and frost that forms on cool nights. Condensation means that there is never enough water vapor to saturate the air at high daytime temperatures. For example, the highest water vapor content ever reported occurred in July of 2003 at Dhahran, Saudi Arabia. The dew point was reported as 35°C (95°F) and the dry bulb was 42°C (108°F). This equates to a vapor content of 3.3%. But the relative humidity was only 68%, so the air was far from saturated.
A summer day in the tropics can feel very humid but the relative humidity is never much above about 60% during the hot afternoon. Relative humidity tends to be highest at night and reaches it’s lowest point during the hot afternoon.
It seems to me that water vapor is a positive feedback but its effect is capped by condensation and greatly damped by the reflection of sunlight from clouds.
Er…did you actually understand what you were writing?
“the surface is constantly radiating about 390 W/m2 upwards”
“And going the other way…..about 330 W/m2 of longwave”
So the net LWIR radiative transport is 390-330= 60 W/m2 which is considerably less than 80+20=100 W/m2.
You have fallen for one of the oldest tricks in the CAGW basket. Radiative transport figures is invariably gross while convective transport is equally invariably net. Please note that neither the descending dry air between convection cells nor the rain is at absolute zero, so there is lots of “downwelling” heat there too.
One of the reasons that it is dry is that it is heated as a result of compression as it descends, not unlike the dry Nevada desert created from air coming down over the top of the Sierra Nevada.
“Evaporative cooling does not remove heat from the earth/atmosphere system, only radiation can do that.”
But, it makes a very big difference whether the heat radiates from the surface or from TOA. Radiation from the surface has to get past the atmospheric filter, and is inhibited in particular by CO2. Radiation from TOA does not encounter that filter.
Very interesting article Willis with much food for thought. Good to see you back.
I will throw out a comment that I have raised many times before, and that is: maybe DWLWIR is not (to any significant extent) absorbed by the oceans and thereby does not (to any significant extent) warm the oceans.
It maybe the case that whilst there is potentially substantial ‘positive feedback’ from water vapour over the tropical oceans (25 to about 33degc), the resulting high level of DWLWIR is a signal incapable of performing sensible work in the environment in which it finds itself, and this is why there is no runaway warming of the tropical oceans.
Whilst there is a negative feedback to high temps (however these temps are generated, ie just solar, or solar + DWLWIR) of evaporative cooling, if ocean temps are governed essentially simply by solar, one does not have the issue that your article raises with potentially runaway DWLWIR and circuitous warming.
I just throw this out as a possible explanation (which may be a component part of a wider explanation).
richard verney July 29, 2016 at 1:29 am
Thanks, Richard. Some of my research takes a while to hack through, and I only write about a subject when I can no longer stand to NOT write about it. Plus I have eight or ten articles started that just petered out for a host of reasons.
And then the writing (and re-writing, and fact checking, and re-re-writing, and the like) all takes a while as well.
And somewhere in there is my own continuing education, reading articles, learning to write better code in shorter time, researching what is known about various subjects, following my monkey-mind from one shiny object to the next …
For those wondering, DWLWIR is downwelling longwave infrared … and here is my comment on the claim that it is not absorbed by the ocean.
We know (because we can measure it and from Stefan-Boltzmann’s equation) that radiative loss from the ocean is on the order of 400 W/m2.
We know (because we can estimate it in a couple of ways) that latent and sensible heat loss from the ocean is on the order of 100 W/m2.
This gives a total loss from the surface of about half a kilowatt per square metre, as a global 24/7 average.
Next, we know (because we can measure it) that the solar energy entering the ocean is on the order of 170 W/m2
We know (because we can measure it) that the downwelling longwave striking the ocean is on the order of 330 W/m2.
If the longwave is absorbed by the ocean, then the energy budget balances—half a kilowatt per square metre in, half a kilowatt out, the ocean neither boils nor freezes.
BUT IF (as you claim) the longwave is not absorbed by the ocean … then the ocean is losing half a kilowatt constantly but it’s only picking up 170 W/m2 from the sun.
So IF your claim is correct, why hasn’t the ocean frozen long ago? A constant imbalance of only 10 W/m2 would cause rapid cooling, and you are proposing that there is a constant imbalance of hundreds of watts per square metre …
Best to you,
w.
PS—The ocean as a global average is warmer than the land. IF as you claim the land can absorb DWLWIR and the ocean cannot, the difference of hundreds of watts per square metre would make the land much, much warmer than the ocean …
“Next, we know (because we can measure it) that the solar energy entering the ocean is on the order of 170 W/m2”
In the tropics, solar energy entering the ocean is over 1,000 W/m2 and penetrates at depth. Once you correct that figure, the absurdity of the atmosphere delivering twice the amount of energy into the ocean as the sun becomes obvious.
FTOP:
Do you understand what averages are? More precisely, do you understand what integrations over space and time are? And do you comprehend the differences between these and peak values?
For fully half the time, even in the tropics, the solar energy entering the ocean is precisely 0 W/m2. The DWLWIR at night there is still over 300 W/m2.
What do you think happens to the energy in the DWLWIR when it strikes the water?
Bob Irvine
The long wave component of solar radiation is absorbed on average to a depth of 0.267 meters in the oceans according to “The Technical Guide to MOM 4.0, 2008” and this is the assumption used by all the CMIP5 models. This energy, as you say adds to OHC by turbulence etc.
On the other hand, CO2 radiated absorption centred at 15 microns is almost totally absorbed in the first fraction of a millimetre, and consequently within the evaporation layer. It is almost totally returned to the atmosphere as latent heat and does not warm the ocean.
Willis you are correct as far as the long wave component of solar is concerned and Crispin is correct for CO2.
The result of this is really messy but should/might mean that the earth’s sensitivity to changes in CO2 is significantly lower than to similar changes in Solar radiation.
Enjoyed the article.
Yes, Ed. I do understand averaging. Because I understand averaging, it becomes plain how non-physical these calculations are. Ocean Tmax is derived completely from solar intensity.
As Bob and TonyL note below, DLWIR (which is completely non-physical) could not cause any upward change in ocean temperature.
The ocean skin layer is well established science and LWIR cannot impact below the cool layer in the temperature profile, which is within the first few microns. Less than the width of a human hair.
To understand the implication of this. Fill a thimble with water. What temperature differential would it have to be to raise the temperature of an Olympic size swimming pool at 20C? When you pour it in, what is the new average temp of the pool?
As you calculate the differential and the average, remember that the water in the thimble is free to evaporate. The reality is that your mythical 300 W/m2 DWLIR is non-physical and the atmosphere is warmed from below and doesn’t raise ocean temps.
Ask yourself this.
Assuming an atmosphere with no radiative gases (CO2, methane, etc.) only water vapor
Accepting that water vapor is the most powerful radiative gas
Initially, all water is in liquid form
Now, when this water evaporates, it extracts energy from the ocean during the phase change
The water below is cooler than before evaporation
The vapor immediately uses energy on ascent and is replaced by colder air
So the question is, how does a process (evaporation) that removes energy from the ocean heat it?
How does the energy that is needed to fight gravity on ascent go back to the ocean without stopping convection?
Assuming water vapor is the only radiative gas, how does it remove energy from the ocean, wisk it away to altitude and have anything left to “heat” the water it just escaped?
If it was returning 300 W/m2 to the ocean, it could not have the energy (heat content) to rise and the evaporative process would fail. No Virginia, the well established properties of water prove there is no DWLIR Santa Claus.
FTOP: Wow! So many misconceptions packed into a single comment!
Let’s start with your assertion that DWLWIR is “completely non-physical”. What is non-physical about it?
– That substances at earth-ambient temperatures emit LWIR?
– That LWIR is capable of traveling downward?
– That this radiation carries energy with it?
– That when this radiation is absorbed, it adds energy to the absorbing body?
Next, you assert that this radiation “could not cause any upward change in ocean temperature” because it is absorbed “within the first few microns.” Let’s examine this. Lots of objects are heated to higher temperatures by radiation that is absorbed right at the surface. Rocks in the sun, for one.
Even visible light penetrates only a tiny fraction (meters or tens of meters) of the ocean’s depth (typically multiple kilometers). So would you say the sun cannot heat the ocean either?
Let’s look carefully at this skin layer. Because water is so opaque to LWIR radiation, virtually all of its emitted radiation comes from this skin layer. At typical temperatures, this is about 400 W/m2 just from the top few microns. If there were no DWLWIR absorbed, this rate of energy loss would be far greater than could be restored by conduction from below, and the surface water would quickly freeze. This can be, and has been, demonstrated in the lab.
So really what the DWLWIR is doing is preventing the surface layer from freezing. In most cases, the DWLWIR is of lower density than the water’s emitted radiation, so it is reducing the power imbalance in the skin layer (but there is still usually an imbalance in favor of outgoing radiation).
Your “thimble” example just shows you have no idea how to analyze thermodynamic systems, as you confuse issues of temperature with heat flow, plus one-off effects with ongoing effects. I have a pool about 12 meters by 4 meters, so about 50 m2. At 20C temperature, the skin layer emits 400 W/m2 x 50 m2 = 20,000 W. But the atmosphere provides about 300 W/m2 x 50 m2 = 15,000 W, so the imbalance in the skin layer from radiation is about 5000 W. This is on an ongoing basis, unlike your one-off thimble example. The pool would cool off far more rapidly in the absence of this DWLWIR.
But what about evaporation, you ask? The skin layer, as thin as it is, is hundreds of times thicker than the evaporative layer. Even if the incoming LWIR is greater than the outgoing (which can happen at night) it doesn’t just cause evaporation.
This is easy to demonstrate in the lab, and I’ve done it. LWIR lasers (10.6 um wavelength) are easy to obtain, and not that expensive. Shine one downward at water in a beaker and observe the results. Your analysis says that it should just evaporate away the water from the surface. But that is not at all what happens. You can easily boil the water in the beaker. And this is without the mixing effect of wind and waves that you get in the ocean — it still heats the bulk of the water.
So yes, Virginia, there is DWLWIR, and it does result in higher water temperatures than would occur without it.
I would like to comment to you and Willis both. I hope the thread is not going stale already.
The absorption of LWIR by water is almost beyond belief. I finally found a quantitative dataset which measures water absorbance across the IR spectrum. It is a paper by a pair of biochemistry people measuring proteins, and so has absolutely nothing to do with the Climate Wars.
Here is the link, the full paper is downloadable as a .pdf
https://www.researchgate.net/publication/223170741_Water_H2O_and_D2O_Molar_Absorptivity_in_the_1000-4000_cm-1Range_and_Quantitative_Infrared_Spectroscopy_of_Aqueous_Solutions
Here is the money shot:
http://i67.tinypic.com/akjpqf.png
Too bad it does not go down to 666 cm-1 there the action is, but there is help. We get the full spectrum for water at NIST:
http://webbook.nist.gov/cgi/cbook.cgi?ID=C7732185&Type=IR-SPEC&Index=1
So now using the two together we can flesh out the Molar Absorbtivity through the LW area of interest.
When I did that I calculated that the thickness of the “thin film” used in the NIST spectrum was on the order of 0.1 micron thick. (I do not have the calculation handy, but I will recreate it if there is interest.)
This basically means that the top micron of the ocean quantitatively absorbs everything that gets there. Looks to me like the energy goes straight to evaporation and not bulk warming.
I expanded a volume of water into 2% moisture and repeated the calculations. That showed that LW IR at 666 cm-1 is near total absorption in about 25 meters.
Absorbance = 3.0
Transmittance = 0.1%
That means getting through the atmosphere, LW must be getting absorbed and re-emitted like crazy.
TonyL,
You said, “Looks to me like the energy goes straight to evaporation and not bulk warming.” Then how do you propose that water exposed to sunlight warms?
Clyde,
What I am referring to here is specifically LWIR, and and more exactly 666 cm-1, (15 um) where CO2 has an absorption band. The big fuss is all about CO2 after all.
When you say “sunlight”, we all take that to commonly mean visible from 400 to 750 nm, and maybe into the NIR as well. Note here that visible has plenty of energy to cause warming. on a photon for photon basis, Vis photons are far more energetic than IR. As you know, visible penetrates very well depositing its energy throughout the illuminated water column. Water also has lots of absorption bands in the NIR but they are nowhere near as intense as the IR bands, so you get at least some penetration into the bulk water.
This shows up in the first 10-100 cm or so. As an aside, water’s NIR bands are in actuality, the higher order harmonics of the big absorption bands in the IR.
No mysteries.
Its UV that warms water…. Far more than IR, which simply does not have the intensity (frequency) to penetrate.
TonyL July 29, 2016 at 8:40 am
RUN THE DAMN NUMBERS, HANDWAVING GOES NOWHERE!!!
Sorry for the shouting, but unless you can show that your claim works QUANTITATIVELY, you are wasting your time and everyone’s time by posting it. Here’s what I mean in this case.
Downwelling longwave at the surface = ~ 330 W/m2 (24/7 global average)
Evaporation = ~ 80 W/m2
Now explain to me again … if downwelling LW is going “straight to evaporation” as you claim, why don’t we have 330 W/m2 of evaporation?
w.
Impressing. But what is exactly “rainfall evaporative cooling”?
Wim Röst July 29, 2016 at 1:43 am
Good question, Wim. In English we have a saying, “What goes up must come down.” What is not so obvious is that what comes down (rain) must first go up (evaporation).
If a location gets a metre of rain in a year, that much water must have evaporated. Since it requires a constant flux of about 80 W/m2 of radiative energy over the period of one year to evaporate a cubic metre of seawater, when that cubic metre of water evaporates it cools the surface by that amount. So a metre of rain represents a rainfall evaporative cooling of 80 W/m2.
I discuss this question further in a post called How Thunderstorms Beat The Heat, which you might enjoy.
Best regards,
w.
Do winds have an effect on evaporation as they do on sublimation?
As I understand it wind speed is an important factor that will throw out any base calculation of constant flux of radiative energy to evaporate x amount of water.
4x wind speed doubles sublimation for example (I think)
So as such this would leave out a primary factor of such a base calculation
Throw in air temperature too actually
Akin to Henry’s law, which concerns a static system of water and gas take up without real world variables, as in say CO2 and oceans.
Thanks Willis, clear.
Am I right that you used rainfall data and not evaporation data to create fig. 6?
Wim Röst July 29, 2016 at 3:16 am
Yep.
w.
Yep
and that’s why you got it all wrong
http://ds.data.jma.go.jp/gmd/jra/jra25_atlas/surface-1/eva-rain_ANN.png
lgl July 29, 2016 at 9:09 am “and that’s why you got it all wrong”.
WR: No Igl. As explained Wim Röst July 29, 2016 at 9:14 am, excess evaporation from elsewhere is (in the tropics) transported by trade winds in the direction of the convection cells. In fact your figure “Evaporation minus precipitation” shows this excess of evaporation elsewhere. The evaporated H2O (and so the energy) is brought by the prevailing winds to convection cells where it is ‘launched’ to a height where the energy can easily be emitted to space.
Willis is right.
It is a dynamic process: the warmer it is, the more thunderstorms, the more emission to space. In this way extra warming in the tropics is diminished. A degree of warming in the tropics will create more thunderstorms which will diminish the degree of warming.
I guess, due to being passed over, I am incorrect. 😀
Mark; evaporation and sublimation are physical processes that take place at the interface between two media, in these cases just two phases of H2O .
Solid-Vapor for sublimation, and liquid-vapor for evaporation.
The immediate effect of both of those processes, is that the atmospheric gas layer immediately adjacent to the solid or liquid interface will have a higher than average density of molecules of water vapor, compared to the atmosphere at large.
As a consequence of that higher abundance, there is an increased likelihood of H2O molecules in the atmosphere falling back into the liquid or solid phase, and at equilibrium, there are as many molecules going one way, as going the other way.
This occurs in virtually all bi-directional physical or chemical processes.
The buildup of vapor H2O molecules in the air slows down the evaporation or sublimation.
The sole contribution of WIND to the process, is that the wind, will physically transport those new H2O vapor molecules away from the interface surface and distribute them in the atmosphere.
This reduction in the near surface density of vapor H2O molecules is what allows the evaporation or sublimation to continue at a faster rate.
In all reactions when elements combine to produce some new product; usually plus some garbage, if you don’t take out the garbage it will pile up and quench the reaction.
It’s really just that simple.
G
One of the big tricks used in GCMs to get water feedback, to get cs high enough to make GCMs warm up, is they allow a super saturation( >100% rel humidity).
This is part of what’s wrong with them.
WR: Am I right that you used rainfall data and not evaporation data to create fig. 6?
Willis Eschenbach July 29, 2016 at 8:46 am “Yep”
WR: That is interesting in this way, that the heat transport upwards is local and is measured in hundreds of hundreds of watts per square metre. But the actual evaporation will partly be located elsewhere, as (trade) winds bring in in the convecting cells the humid surface air from possibly far away. So, in fact this is a system to cool the whole tropics.
Typo: “hundreds of hundreds of watts per square metre” must be “hundreds of watts per square metre”
And translated better: “as (trade) winds bring into the convecting cells the humid surface air from possibly far away.”
Willis
Your quote
“Downwelling longwave at the surface = ~ 330 W/m2 (24/7 global average)
Evaporation = ~ 80 W/m2
Now explain to me again … if downwelling LW is going “straight to evaporation” as you claim, why don’t we have 330 W/m2 of evaporation?”
Most of the 330 w/m2 DLWR you mention would come from either solar or water vapour and according to the MOM 4.0 used by the GCMs would have an average attenuation in the oceans of 0.267 meters. You are correct to say that this energy is almost totally included in OHC and warms the ocean as it is overwhelmingly absorbed below the evaporation layer. It will be readily mixed by turbulence, wave action etc.
CO2 on the other hand is almost totally absorbed in the evaporation layer with a significantly higher proportion being returned to the atmosphere as evaporation.
This explains the discrepancy between DLWR and evaporation you mentioned above, but also means that Tony and Crispin are correct as far as CO2 is concerned.
https://wattsupwiththat.com/2010/09/14/spencer-on-water-vapor-feedback
This is explained excellently and gives a very good perspective on this subject.
My conclusion is an increase in on water vapor overall likely would promote global warming al factors being considered, but as this article says the key is what is happening to the water vapor content in the stratosphere.
From my point of view the overall GHG gas effect is a result of the climate not the cause.
I am probably misunderstanding something but if I look at your first plot it shows about 150 watts/sqM atmospheric absorption at the average 29 kg/sqM atmospheric water content. But we know the surface at the average temperature of 288K emits 390 watts/sqM. Thus if the atmosphere only absorbs 150 it suggests 390 -150 gets through to outer space ie: 240 watts/sqM. But we know the total loss to outer space is about 243 watts/sqM. That seems to imply just about all the emission to space is radiation from the surface not absorbed by the atmosphere. Hardly in agreement with Trenberth et al who claim only 40 watts/sqM of the surface emission escapes to space. Also, if the atmosphere absorbs it must also emit (emissivity=absorptivity) in all directions up as well as down. At some altitude such emissions will escape to space and the intensity of emission depends on the temperature. Even if it all occurs from the coldest point in the atmosphere (the tropopause at about 220K) that would still be significant and would add to the 240 watt/sqM passing straight through the atmosphere. The again if energy absorption rises it means the atmosphere is becoming more opaque (at the thermal infrared wavelengths) and that would also mean it would emit more energy to space (ie: if its absorptivity rises so does its emissivity).
Is the energy reflection by clouds additional to your 150 watts/sqM? If so, assuming Trenberth is right (OK I admit that’s a very large IF) clouds would have to be reflecting about 200 watts/sqM which is even larger than the atmospheric absorption. I guess its possible if cloud cover is 60% (60% of 390 = 234watts/sqM). But then again that should be 60% of 390-150 = ( 144) since the clouds cannot very well reflect the energy already absorbed by the atmosphere. Either way cloud effects are as large at atmospheric absorption and thus cannot possibly be ignored in any analysis
Then again evaporative cooling transfers the energy to the atmosphere not to space. Increased energy loss to space would only occur if the atmosphere at the altitude where it is emitting to space would be rising since emission depends on temperature and that means we should be seeing a significant rise in upper atmosphere temperatures particularly in the tropics – exactly what the CAGW proponents predict yet which 1000’s of balloon flights show is not happening.
Sorry if the above sounds a bit disjointed, I wanted to give some feedback before the comments get overwhelming, your analysis is interesting (I need to study it in more detail) but I cant help but feel there is more to this issue.
Michael Hammer July 29, 2016 at 2:47 am Edit
Good question, Michael. The figures are solely for clear-sky conditions, meaning no clouds. Clouds cover nearly 70% of the planet and are generally blackbodies w.r.t. longwave, so they absorb a lot of radiation.
w.
So, they absorb a “lot” of long wave radiation. What does mean?
It seems to me that it drives the clouds to a higher elevation where that heat is lost mostly into space ( even more efficiently).
To be ” near BB ” a body needs only to be able to absorb almost all of the incident EM radiation in a 16 to one spectral wavelength range appropriate to the Temperature of the body.
98 % of the radiation of a BB lies between wavelengths from one half of the radiance peak wavelength, to eight times that peak wavelength. 25% (almost exactly) of the total energy lies at wavelengths shorter than the peak, and 75% is longer than the peak. Only 1% lies beyond either end of that 0.5 to 8.0 times the peak wavelength.
For 288 K the peak wavelength determined from the Wiens Displacement Law is about 10.1 microns; about 20 times the solar spectrum peak wavelength corresponding to about 5760 K for the sun surface Temperature.
G
Again the climate stability notion Willis keeps trying to push is all relative to how one views climate stability.. For example I view the climate system as being unstable just based on the change in N.H. temperatures from the Medieval Warm Period to the Little Ice Age to present and the impact those changes have had and are having on humanity..
With solar prolonged minimum conditions becoming more established (finally ) once again the factors which govern the climate system which is DRIVEN by the sun will be influenced and if solar activity is EXTREME enough they will be influenced to a degree which will cause the climate to change especially if climatic thresholds are met.
Past history shows beyond a doubt that this has occurred due to the many documented abrupt climate changes shown in the ice core record.
I suggest what I just wrote to convey that the climate system as far as humanity is concerned is not stable
The increase of total water vapor with SST on a gridpoint basis will be larger than that computed from large-scale area averages (say, over the whole tropics). The former (gridpoint-based) will be dominated by geographic differences, which are strongly affected by vertical circulation systems that cause water vapor to converge and deepen over warm SSTs and decrease over cooler SSTs; the latter (large scale area averages) will be dominated by interannual variations in the whole system (say, from La Nina and El Nino) and are usually used as a possible surrogate for a climate change response.
Thanks for these articles.
You look at clear sky absorbtion, but how about all sky or clouds only?
The word absorbtion as ingoing minus outgoing is possible to use that way, but with an actve radiating atmosphere it could lead to amplification in rare instances.
Willis,
” that’s a serious amount of cooling, about ten watts of additional cooling per additional kg of precipitable water”
I don’t understand this argument. I presume it means that if there is a sustained increase of 1kg PW, the rain increases and the latent heat associated with its condensation is 10 watts. But the latent heat at condensation has a warming effect, not cooling. The cooling happens when the water is first evaporated. And the two must balance if PW is steady; no net heat can be created if the water starts and ends as liquid at SST temp. So the latent heat allows vertical transport (Trenberth’s 80 W/m2), but it doesn’t cause net cooling.
Cooling is heat leaving the system. If head energy gets from surface ( SST ) to tropopause,it’s half way out of the climate system.
“Cooling is heat leaving the system.”
Yes, the water cycle augments heat transport. But to convert that quantitatively to a cooling rate would involve some heavy duty analysis, with a spectral GHG analysis, levels of atmosphere etc. And I don’t see any indication of that being done here.
Nick:
The notebook computer I am using to type this comment has a thermal system that evaporates/boils water over the processor and then condenses it to the outside of the computer at ambient temperatures. This is the cooling system for the computer.
Similarly, the surface evaporation cools the surface, and as the water vapor condenses high in the atmosphere, the warming effect here is better able to be rejected to the ambient of space, as it is above most of the radiative absorption of the atmosphere.
Trenberth’s 80 W/m2 of latent heat loss from the surface is a NET value of this effect.
The latent heat of evaporation; amounting to something like 590 cal/gm, (depending on the Temperature at which the phase change occurs), is now part and parcel of the WATER VAPOR, and as correctly mentioned by somebody here, it is PHYSICALLY transported by CONVECTION to the upper atmosphere, which somebody also said could be at -60 deg. C (have actually been in an aero-plane over the Pacific, reporting exactly that outside air Temperature for all the passengers to read.)
Somewhere along that upward path, the formerly warm H2O vapor gets cooled (LOSES HEAT) to the cooler air (the two are physically mixed and exchange heat energy among themselves).
ONLY after the LATENT HEAT has already been lost by the H2O VAPOR to the N2 and O2 and Ar of the dry atmosphere, can that H2O molecules find a low curvature substrate surface (microbe or dust particle), at a Temperature somewhere near the DEW POINT Temperature, CONDENSE (not precipitate), and become LIQUID water droplets, which can then grow; or perhaps after losing another 80 cal/gm (if cold enough) , and become solid ice crystals.
So the water droplets or ice crystals that make VISIBLE clouds, have already disgorged all of the latent heat of phase change, that they PHYSICALLY transported from the surface (ocean maybe) up into the upper atmosphere, where it will eventually be lost to space by various sequences of processes.
The RAIN or SNOW or other precipitation which ultimately occurs when it gets too dense to support, will fall to earth (through an increasingly warm atmosphere of air) which will somewhat warm the precipitate, to its final Temperature as it lands back on earth or back in the ocean.
Its Temperature is entirely due to the HEAT energy that may reabsorb from the ordinary atmosphere gases, in CONDUCTIVE heat exchange processes, on the way back to the surface.
The H2O while in either of its condensed phases, makes a very fine efficient radiator of THERMAL LWIR radiant energy, at whatever the ambient Temperature happens to be where those clouds are, and maybe half of that goes towards space, and the other half towards the surface, so the clouds comprise an effective near BB like thermal radiator at whatever the local Temperature happens to be.
The atmospheric H2O VAPOR on the other hand, is a low emissivity thermal radiator (due to its Temperature), but also a good radiator of molecular LWIR spectral radiation (that which is characteristic of the H2O molecule. (CO2 does likewise).
Yes it is true that in daylight, the atmospheric water in all three phases will absorb some parts of the incoming solar spectrum radiant energy (short wave or near IR), which will locally warm the atmosphere, BUT ! the majority of the incoming solar energy reaches the surface at about 1,000 W/ m^2 (NOT 341 or 250 or any other average number), and 3/4 of that surface is deep ocean water into which the solar beam penetrates to depths of tens to hundreds of meters.
It will be eons, before the oceans manage to distribute that 1,000 W/m^2 solar beam, around the entire planet, to establish some 288 K supposed mean Temperature at which it can possible radiate some 390 W/m^2 in a 10 micron peaked wavelength spectrum.
Clouds don’t even come into existence until the HEAT ENERGY (noun) in the form of latent heat of phase change, is entirely removed from the H2O molecules by CONDUCTION.
The COLD air (there’s masses of it) COOLS the water vapor (there’s much less of that).
The “latent heat” is NOT going to stop the upper atmosphere from getting down to -60 deg. C outside your aero-plane.
The exact Temperature at which the phase change occurs from (atmospheric) water vapor to CONDENSED clouds depends on a host of factors which are generally recognized, in the form of some sort of “dew point” Temperature, but also the local availability of a nucleation substrate to obviate the need for an infinite internal pressure in a zero radius water droplet . (surface tension delta p = 2 t / r) )
G
I don’t own any text books on “forcings” so I don’t do those calculations; so I stay with the Physics.
GES,
You said, “Somewhere along that upward path, the formerly warm H2O vapor gets cooled (LOSES HEAT) to the cooler air (the two are physically mixed and exchange heat energy among themselves).”
Now, if the warm air were diffusing upward, it would be well mixed and it could lose heat by conduction. However, for strong convection, such as at the base of a cumulonimbus cloud, there isn’t strong mixing and that is what preserves the latent energy and precipitable water. It is the application of the Ideal Gas Law that explains the cooling of the water vapor and the associated air. The liquid water can be cooled by conduction when it condenses, and is still being lofted upwards by convection. The ‘cell’ contains an air mass that is physically different from the surrounding air that you consider to be responsible for conductive cooling “among themselves.”
Well Clyde, a single H2O molecule in the atmosphere; well mixed or not, is surrounded by hundreds or tens of ordinary N2 , O2, and Ar molecules. For CO2 it’s about 2500 molecules surrounding one CO2, maybe 13 molecular layers thick to the closest (average) next CO2 molecule.
So even in unwellmixed air, an H2O molecule is in thousands of collisions per second with the ordinary air molecules, so they reach the exact same local Temperature in microseconds or milliseconds.
So it is the whole mass of atmosphere that is rising in convective up drafts, not just the H2O.
So an H2O molecule remains in statistical thermodynamic Temperature equilibrium with the surrounding air as they all rise in altitude, and they all reach the (near) Dew point Temperature together, at whatever the lapse rate happens to be.
Only the H2O molecule knows that it is on average too energetic to join together with other H2O molecules and form a droplet. So that process is often, and maybe usually delayed, until a suitable low curvature substrate is encountered, on which the H2O molecules can deposit as a covering water layer.
Any notion that any single H2O molecule remains at some elevated Temperature relative to the air for some reason, is bogus. The H2O molecule will rapidly fall into place on the Maxwell-Boltzmann equi-partitioned kinetic energy range appropriate for that Temperature.
The Eqi-partition law holds in general for any mix of gas molecular species. Now some species will have different numbers of degrees of freedom, and for those each degree of freedom is equally endowed with mean KE appropriate to that local Temperature.
G
@Nick
> … it doesn’t cause net cooling.
This is correct only in the sense that the heat of evaporation is returned by the heat of condensation. But as Greg also points out, this heat of condensation is returned in the high troposphere, in these large tropical convection systems, above most of the earth’s warming planetary blanket of air.
Yes, some of this heat will be directed downward and will be “trapped” in the blanket, but the other half will be radiated (and of course, not convected) upward where the path to outer space is now much freer.
http://images.slideplayer.com/24/7319525/slides/slide_35.jpg
You can see this image that convection does indeed stop at the tropopause (with a little “overshoot” here and there of course), but radiation does not.
So the 10 W/m^2 cooling computed by Willis does seem consistent with this notion.
Johanus says, July 29, 2016 at 9:24 am:
No. All the heat drawn from the surface and up into the troposphere is radiated to space as Earth system heat loss. We’re in a dynamic steady state, Johanus. If half the heat were continuously being radiated back down, into the system, Earth would heat without end. At dynamic equilibrium, as much energy always exits the Earth system to space as heat as what enters as heat from the Sun. This is Thermodynamics 101.
As I said, some of the downward LWIR radiation is “trapped” (quoted to show irony), in the sense that is absorbed and raises the temperature of the planet as sensible heat, raising the expected black body temperature from 255K to 288K. The upward radiation has no effect on the surface temperature so, in effect, cools the surface (the point I was reinforcing.
But, yes, all of the input radiation is eventually returned to space, once radiant equilibrium is achieved. To see this, imagine that the Sun suddenly disappears. Then the terrestrial temperature will plunge toward absolute zero as earth radiates the previously absorbed solar energy into space. (But will never quite achieve 0K because of internal geothermal energy)
Johanus:
No. Accumulation of energy inside the Earth system only occurs between t_0 and t_1, when it warms from initial heating (by the Sun) to the final steady state (when heat OUT=heat IN). This accumulation is what gives the Earth its temperature(s).
Are you being serious here, Nick? Evaporation is cooling the SURFACE. Parallel to the Sun heating it. It’s pretty obvious Willis is talking about the SURFACE, not the troposphere above. The latent heat of vaporization, drawn from the surface upon evaporation and later released in the tropospheric column upon condensation is not returned to the surface. It is radiated to space. As Earth system heat loss. The water returns, not the energy. That’s how heat generally flows through the Earth system: Sun > surface > troposphere > space.
Nick Stokes July 29, 2016 at 3:51 am
Thanks, Nick. I had said:
I apologize for the lack of clarity. I had thought that the subject under discussion was clearly the surface and not the planet, since the evaporation directly cools the surface, and the temperature in all the charts is the surface temperature. You are right that the globe doesn’t directly lose energy in the form of latent heat.
However, as I discussed elsewhere on this thread, the effects of evaporation and convective rainfall activity can indeed create net global cooling.
My best to you,
w.
“‘..effects of evaporation and convective rainfall activity can indeed create net global cooling…”
Not multi-annually Willis – over long periods they balance. Sure the evaporation in the Pacific cooled but then the rain over Ca. warmed. Willis demonstrates no net global cooling from the multi-annualized effects of evaporation and convective rainfall data as he shows balanced here, Willis: “the model I developed over a decade ago”..:
https://wattsupwiththat.com/2016/07/28/precipitable-water-redux/comment-page-1/#comment-2268428
Emitted & “Absorbed by troposphere” running R to L:
22+58+76+339-321-321+147 = 0
Balanced, no net cooling from effects of evaporation and convective rainfall data, per Willis’ own chart.
Trick August 3, 2016 at 2:50 pm Edit
Mmmm … perhaps you misunderstood me, likely my fault. It may be we are discussing different kinds of cooling. By “net global cooling”, I am talking about the global average surface temperature. It’s clear that I’m not talking about the top-of-atmosphere cooling or warming. There is 340 W/m2 entering the system at the TOA, and given that the system is observably in general overall dynamic balance, there has to be 340 W/m2 leaving the TOA. And indeed, this is verified by the CERES satellite data.
However, while the TOA has to balance as you say, there is no such requirement regarding the surface. It is currently running well above the expected Stefan-Boltzmann temperature … and it could easily run at some cooler temperature. Suppose, for example, that the clouds change just a little bit, increasing the albedo from ~30 to ~31% … the system would run cooler “over long periods”.
And in the comment above from which you have quoted, I listed a number of ways that evaporation and convective rainfall activity affect the global temperature, both by actively reducing incoming energy, and by actively cooling the surface. The big effects are the changes in cloud, surface, and ocean albedo; the greatly increased evaporation due to the thunderstorms; and the change in the rate at which the ITCZ thunderstorms circulate the heat from the tropics to the poles.
Regards,
w.
Willis, a very interesting basic view:
Willis Eschenbach August 3, 2016 at 3:11 pm
“However, while the TOA has to balance as you say, there is no such requirement regarding the surface. It is currently running well above the expected Stefan-Boltzmann temperature … and it could easily run at some cooler temperature. Suppose, for example, that the clouds change just a little bit, increasing the albedo from ~30 to ~31% … the system would run cooler “over long periods”.
And in the comment above from which you have quoted, I listed a number of ways that evaporation and convective rainfall activity affect the global temperature, both by actively reducing incoming energy, and by actively cooling the surface. The big effects are the changes in cloud, surface, and ocean albedo; the greatly increased evaporation due to the thunderstorms; and the change in the rate at which the ITCZ thunderstorms circulate the heat from the tropics to the poles.”
WR: I had a first look at ‘Boltzmann – Earth Temperature’. Wikipedia:
https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law#Effective_Temperature_of_the_Earth
“(…) As a result, the Earth’s actual average surface temperature is about 288 K (15 °C), which is higher than the 255 K effective temperature, and even higher than the 279 K temperature that a black body would have.”
WR: And the Earth’s average surface temperature and the average temperature of the deep sea have been far higher in the past, as Paleo data tell:
http://d29qn7q9z0j1p6.cloudfront.net/content/roypta/371/2001/20120294/F1.large.jpg
http://www.alpineanalytics.com/Climate/DeepTime/WebDownloadImages/CenozoicTsGlobal-7.5w.600ppi.png
Apparently for the Earth’s average surface temperature there is a wide variability possible. For example, our present cool deep oceans give an enormous possibility to cool the surface. What will happen with the Earth’s average temperatures when Earth’s average wind speed enhances at the places where cold water upwells? Isn’t this what happens when more thunderstorms develop?
Willis – Good discussion thx. In your gray band labeled “Absorbed by Troposphere” your example processes* might of course change over periods observed to take net energy out of that zone leading to “net global cooling” in that zone for the period (KT97 was 5yr.s in the mid-80’s, you do not specify a period here). A new annual balance would be established after a transient rebalancing.
My point is things are pretty much balanced around 287-289K Tmedian meaning rain and evaporation are likewise pretty much balanced (76 up, 76 down give or take) for your gray area over the periods we’ve observed. Climate changes, so that will change. You can see the small natural changes even in the data (mid-80’s KT97, 2000 – 2004 in KT09, 2000-2010 in Stephens12) but they all stay in ~balance, perfectly in yours.
*”changes in cloud, surface, and ocean albedo; the greatly increased evaporation due to the thunderstorms; and the change in the rate at which the ITCZ thunderstorms circulate the heat from the tropics to the poles.”
The vertical transport of heat causes net cooling because warmth at higher elevations radiates to space more efficiently than warmth at lower elevations.
Cheers, 🙂
In 70s I published several articles in the India Meteorological Journal [Indian J. Met. Hydrol. Geophy.] to estimate parameters that were measured over few stations with data measured over wide networ. They included rainfall versus sunshine/cloud cover, global solar radiation & net radiation, evaporation & evapotranspiration. One such paper published in 1976, 27:163-166 “Simple formulae for the estimation of wet bulb temperature and precipitable water.
The total moisture content of the atmosphere is expressed by the precipitable water vapour in the atmosphere. This is defined as the depth of liquid water that would result by condensing all the vapour in the vertical column of the atmosphere over one square centimeter cross-section.
Tw = T [0.45 + 0.006 x h x square root (p/1060)
and
W = = c’ x square of Tw
Tw = wet bulb temperature in oC — daily orhourly
T = dry bulb temperature in oC — daily or hourly
h = relative humidity in % — daily or hourly
W = precipitable water vapour in gm/square centimeter — daily or hourly values
c = regression coefficient vary with season [months] — c’ = 1/ square of c — based on the radiosonde data measurements at 12 12 stations for 6 years was used.
Dr. S. Jeevananda Reddy
So ” precipitable water vapor ” is (by definition) the TOTAL water VAPOR in the atmosphere.
ergo clouds are NOT PWV; that is NOT water vapor.
G
Why do they have to make such a big deal out of “It’s the atmospheric water vapor ” ???
GES,
There are often problems in science, and philosophy especially, resulting from not carefully defining terms. If “precipitation” is that which falls from the sky (a commonly accepted definition), then I guess we could call clouds “unborn precipitation.” It isn’t water vapor any longer, but it hasn’t yet formed droplets large enough to fall and therefore isn’t really precipitation. So, I think we should take Willis to task for not carefully defining “precipitable water” when he started this series. However, I suspect that clouds are not included in the definition because of the ways in which the parameter are determined. That is, one can’t see with a satellite sensor what is under a thick cloud, so nothing intelligible can be said about what is in the water vapor column when there are intervening clouds.
Clyde, my comment (above) about precipitable water vapor, was really a rhetorical question to Dr. Reddy above where he defined PVW in the form of a depth of liquid water that could be condensed out of the water vapor in that column of air.
As such that is literally ALL of the water in that column, since the cloud part of it is simply already condensed, and on its way to precipitating.
IT IS NOT MY DEFINITION.
…… Precipitable Water Vapor …… is just about (but not quite) the stupidest damn pseudo scientific mumbo jumbo ever foisted on us as some sort of supposedly useful information.
The atmospheric air column from the condensed state earth surface out to maybe halfway to the sun, contains H2O molecules either in the form of a gas (vapor) or liquid droplets or ice crystals, or all three of those, and as such that water contributes to the total atmospheric pressure on the surface, which adds to that pressure cause by N2, O2, Ar and a zillion other atomic / molecular species.
If you put all of that water in a bucket, you have your PWV. That is ALL of the water in that atmosphere column so you can’t get any more precipitated no matter what.
As for what that means for our climate. One would expect that in each of those three phases, each type interacts with atmospheric energy, either radiative (from zero frequency to zero wavelength) or thermally as ” HEAT ” which is the random kinetic energy (mechanical) of matter at Temperatures greater than zero kelvin, and those interactions are likely to be different for each of the phases.
The study that Willis presents here attempts to make some sense out of those differing processes.
I don’t pretend to understand just how Willis’s manipulations all work; but he usually does his homework; so I just accept that some readers do understand it.
But the notion that somehow water in the atmosphere is special if it is precipitable, is about as sensible as the equally silly notion that CO2 in the atmosphere has a half life or a residence time.
BOTH H2O and CO2 are PERMANENT components of the atmosphere, in varying amounts that change with time and location.
It matters not if one CO2 molecule, or one H2O molecule gets replaced by another.
It only matters how many of each there are at any given time or location.
Mother Gaia knows how many there are and where they all are so she sets the Temperature to be just what it is supposed to be; and it always is; no matter what.
And it almost NEVER EVER has the global average Temperature ANYWHERE, or at ANY TIME.
Only people pay any attention to the average. Planet earth does not.
G
PS.
Note my rant is not any criticism aimed at Willis’s analysis here; so don’t get the idea that it is.
Whether H2O is precipitable or not is just how you define it.
So it is about as useful as climate sensitivity.
Everybody defines it a different way, and then everybody else talks about it as if we are all talking about the same thing.
No amount of mathematical statistical prestidigitation can establish that a “Climate Sensitivity (S) “, (whatever the hell that is) of 2.00 is perfectly acceptable and we can live with that forever; but if it comes out to 2.01, then we are all doomed to roast.
Nor does where the water in the atmosphere is today matter.
G
Having lived in the tropics for many years, I can testify from personal experience that the almost daily “3Oclock thunder plump” drops a load of rain and the temperature by 10 degrees or more.
No argument! It happens!.
except, as Nick Stokes points out above, the cooling at the surface caused by evaporation and convective rainfall activity is exactly balanced by heating in the upper troposphere where the condensation takes place. There is no net cooling of the climate system.
“balanced by heating in the upper troposphere where the condensation takes place”
Dr. Spencer, what happens with the energy from the condensation in the upper troposphere, will it fully be emitted to space?
If so, what would have happened if the same amount of energy would have stayed down at the surface, how much would have been emitted?
As I just comment to Nick above, heat leaving the climate system leaves the surface and rises as latent heat. It then returns to sensible heat in the upper troposphere. At this point it is half way on it’s journey into space. Though at this point is it correct to say that there is not yet any net heat loss to system as measured at TOA.
“There is no net cooling of the climate system.”
Convection certainly doesn’t transfer heat to space.
However, the so-called Lapse Rate Feedback is negative, no?
The ( modeled, but missing for the satellite era ) Hot Spot reduces the net radiative imbalance.
The shape of the warming ( that is, the vertical profile ) can certainly effect the efficiency of radiance to space.
Sure, but I thought the impacts of AGW (the reason for all of the alarm) generally required warming at or near the surface. How is a warming of the troposphere going to drive increases in SLR? How will this adversely affect agriculture, or drive species extinctions?
Disagree about no net cooling. The latent heat of evaporation released by condensation is released higher in the troposphere, closer to the effective radiating altitude. Therefore there is relatively more cooling as the GHE is less. Analogy to thinner insulation.
I’m with Wim and Greg here and don’t get the ‘no net cooling argument’ at all. The energy may (must!) balance if you consider the evaporation/convection a closed system, but it isn’t. Nor is it ever at true equilibrium. Once at the lower pressure of the upper atmosphere, radiation efficiency to space is far greater because there’s less chance of interception of the photon by another molecule. So you move energy from a part of the Earth system where radiation is relatively inefficient to where it is highly efficient. It’s like taking a blanket off and similarly must result in a higher rate of heat loss.
Surely convection and condensation (cloud formation) is especially important because the energy exchange is very sudden at the condensation point. So heat can move quickly from the surface to altitude and be released very quickly. Incoming solar is highly variable over the 24 hrs (duh!), whereas convection can take place whenever there is the energy to facilitate it.
All that convection has to be balanced by incoming cooler air and that presumably further increases heat loss at the surface as a result of convection.
What am I missing?
Disagree about no net cooling. The latent heat of evaporation released by condensation is released higher in the troposphere, closer to the effective radiating altitude. Therefore there is relatively more cooling as the GHE is less.
I think that’s true –
1. Convect heat and humidity from lower to upper levels, and upper levels radiate more effectively.
2. But, more heat & humidity in the upper levels, means the lower levels radiate less effectively.
3. But that leads to cooling over warming, which leads to… more convection,
4. which leads to… ( 1. above )
The Hot Spot is a reflection of convection in the models which in theory leads to some negative feedback.
BUT – that feedback is not 100% of delta CO2+H2O.
Warming, in the context of unknowns and variability, should ensue, just not at rate implied by twice the forcing from CO2.
And the Hot Spot hasn’t occurred for the satellite era, so does that mean LR feedback hasn’t occurred?
damn ! we can’t get nothing for nothing !
G
Nobody ever accounts for the mgh involved in getting the H2O from down here to up there (and back later)
g
Roy Spencer
July 29, 2016 at 4:26 am
except, as Nick Stokes points out above, the cooling at the surface caused by evaporation and convective rainfall activity is exactly balanced by heating in the upper troposphere where the condensation takes place. There is no net cooling of the climate system.
I’ll just state this as kind of Postulate involving Energy Balance since I’ve never officially studied Radiative Physics:
Sun-warmed surface layer water leads to increased water vapor which emits infrared light. Not all of its Energy is Kinetic. Therefore I don’t see how some % of water vapor’s infrared light Energy isn’t lost to Space, since E=mcc. In other words, I’m saying the Sun’s incoming Energy which quickly increases [more or less] the evaporation of water at the surface, and [more or less] the cooling there, is balanced by the Energy used in the upper troposphere when condensation takes place + the [more or less] Energy lost to Space by water vapor’s infrared = net Energy loss and [more or less] cooling.
Dixon July 29, 2016 at 8:37 am:
“All that convection has to be balanced by incoming cooler air and that presumably further increases heat loss at the surface as a result of convection.
What am I missing?”
Dixon, your cooler air is very dry. As is explained by Dr. William Gray: http://icecap.us/images/uploads/Crux_Flawed_Science.pdf
The lowering air from the top of a thunderstorm can have a Relative Humidity of only 7% as it returns to sea level (table 4). The dry air is perfect for rapid evaporation, helped by the strong winds which – as far as I remember – have an exponential effect on evaporation.
The article of Dr. Gray is very interesting. Hereby his conclusion on evaporation:
“Real global warming to be expected.
Without upper-troposphere water-vapor change
and without enhanced surface evaporation cooling associated with extra rainfall, the
pure radiation response to a doubling of CO2 would indicate we should expect about a
1.0oC global warming. But even with zero assumed water-vapor change this 1oC
warming is two to three times larger than what will likely take place. This is because
about 60 percent of the 3.7 Wm-2 IR blocking to space from a doubling of CO2 will be
balanced by an enhancement of surface evaporation and an increase of the global
hydrologic cycle by about 2½ to 3 percent. A zero water-vapor feedback will thus be
expected to only bring about a 0.4oC global temperature rise from CO2 doubling.
We show that there is a very modest degree of negative water-vapor feedback of 0.1 to
0.2oC. With this occurring we should expect that the real amount of global warming that
will occur from a doubling of CO2 would be only about 0.2-0.3oC or about 5-10 percent
the amount projected by the many global models of 2-4oC. The AGW threat and
especially the catastrophic AGW (or CAGW) threat cannot be a realistic assertion of
how the planet’s climate system functions.”
Hi Wim,
Thanks for that. So in summary, I’m not missing anything and Dr Spencer and others are wrong? That’s not a very comfortable position for me to be in!
I’m struggling to believe the GCMs can really have such a crude approximation of water vapour. I knew they didn’t do clouds and fine-scale very well, but I didn’t realise it was that fundamental. How have the atmospheric physicists been complicit with such shoddy science? There must be enough of them modelling convection on fine spatial scales to be able to call bull in the peer reviewed literature on parameterisation of water vapour if that paper you gave the link for is a reasonable summation. It’s not like this is all that new. Or does peer-review of climate models not go to people who actually understand the real science behind the elements of the models? I can see why some scientific fields are wary of getting into the climate debate, but it really is unforgivable if your field overlaps their fundamental ‘science’.
As I read the link I was reminded of tephigrams and wish I’d paid more attention when I had the benefit of an uncorrupted Met man to explain them properly. I could have got to this enlightened state 20 years ago. Pretty sure there should be a lot of publicly available data from research aircraft out there, but of course that’s weather, not climate, so there’s probably no money or interest in it.
I live in Perth Australia and I only realised very recently that the howling dry easterlies we get in summer are part of Hadley circulation. They suck the moisture out of your lungs with every breath. But give me 37C and 5% humidity over 30C and 100% humidity any day.
Hello Dixon,
I can reassure you, I didn’t do an extensive research whether you’re not missing anything besides what I was telling you. And about the well respected Dr. Spencer and others I can only say that I am reading with interest all they are writing and that I try to get the fundamental things out of their knowledge and from their points of view. So you must feel more comfortable now!
As far as I know, the role of water vapour in the models is based on assumptions. If it indeed is, the feedback of water vapour is the big lie, the lie which was necessary to make the problem ‘really dangerous’. It is very interesting what Bill Illis July 29, 2016 at 6:53 am said about the water feedback:
“The +2.4 W/m2 per 1.0C is, thus, a VERY important number. It is “everything”. If, in reality, the feedbacks are only half of predicted, global warming would fall to 1.6C per doubling. If it were one-quarter, warming falls to 1.3C per doubling. If it were twice as big, well, global warming would then +47.0C per doubling and there would be a runaway greenhouse effect.
That is how finely tuned the chosen feedbacks are. It is the difference between benign-nothing warming and a runaway greenhouse effect.”
WR: ‘Finely tuned’ ! Indeed! “If it were twice as big, well, global warming would then +47.0C per doubling and there would be a runaway greenhouse effect.”
Like you, I am understanding more and more about how the whole problem (dangerous warming) is created and which tricks were used in trying to make all of us ‘people with fear’. To be honest: not too long ago I was one of those who had some fear, even while I – as a geographer – was better informed about climate than most of the other people. Fortunately there was that excellent book “De staat van het klimaat” by Marcel Crok that opened my eyes. And I found websites like this with persons with a feeling for what is right (being honest) and for what good science should be. In this way someone’s point of view can become more realistic.
And fortunately there are persons like Willis who have the skills and the insight to reveal more about the real functioning of climate than hundreds – if not thousands – of well paid researchers do. This last group, the well paid researcher, is mostly living in his or her ‘virtual world’ and is producing ‘variations’ of biased research based on at least partly wrong assumptions. Like about the feedback of water vapour.
On this website recently someone wrote a comment about ‘group think’. Researchers are forming a group and all are sharing a need for confirming investigations as wanted by the public, the government, their own institutes and themselves. But that research is far from the fundamental scientific research that would be needed to get the big lie out of the climate ‘debate’. Therefore you must dare to have doubt about what 97% is believing.
I myself am living in Holland and fortunately we have had some warming here last century. Mainland western Europe is from the densely populated regions the region that warmed most, I think. But still, as we have in Holland our warmest period of the year – summertime – during holidays our people are fleeing to countries where they can find temperatures 5 to 10 degrees higher than our present (2016) average (day and night) July temperature of 18,4ºC. From our population of 17 million, countries like Portugal, Spain, Greece, former Yugoslavia and Turkey – the really hot ones – attracted last year in summertime (!) 3 million Dutch to celebrate their holidays in their country. Nearly all returned happily and no fatal climate problems have been reported nor for the local people nor for the Dutch. Even not after the ‘unprecedented warming’ of last century. On the contrary, Dutch still like ‘warmer’. At least during their summer holidays. And in autumn, winter and spring.
As always an interesting post Willis.
Willis,
You wrote –
“So … with such a large radiative feedback from water vapor, three to four watts per square metre per degree and much higher in the tropics, why is there not runaway feedback”
Because at night time, the sun is not shining.
The surface cools. Hardly rocket science – any reasonably intelligent 12 year old can explain it.
Neither H2O nor CO2 heat anything. No feedback – complete nonsense. The surface warms during the day, and cools at night. Only dimwits and climatologists think otherwise.
Cheers.
The surface cools.
Does it cool faster with high humidity above, radiating infrared on it?
Or does it cool faster with low humidity above and little downward infrared radiating on it?
I think you will find the latter.
Willis: “Here is the main figure from that post showing the relationship:”
Not quite, this is the same as your earlier graph but this time with a linear scale, not log scale. This is useful as a second way to visualise the data.
The caption to fig. 1 says: ” The slope of the curve at any point is 62.8/TPW (W/m2 per degree)”
This is clearly not correct. The slope of that graph varies notably. It is the slope of the log graph which is constant.
This ties in with a comment I made in the previous thread about the change in slope as TPW increases.
As TWP increases the slope decreases. This means that the magnitude of the positive feedback decreases. While remaining positive and finite it is reducing in magnitude.
At 12 kg/m^2 the slope looks to be about 5 W/kg. At your ‘average’ point it is less then half that.
So this is positive feedback which is itself subject to a negative feedback. The negative f/b being the masking effect as the density of water molecules rises. They become masked by others and the net effect of a give increase is less and less. This is the classic log relationship of absorption.
This shows that the positive w.v. feedback will be stronger in cooler, higher latitudes than in the warm and humid tropics.
But the negative feedback limiting water vapor also increases as well.
Willis, many thanks for the time and effort you put into these articles. Always interesting, even though a lot of it goes over my head.
My questions is – “Why do you need to look for these relationships when the (so-called) ‘climate scientists’ should already know how these physical processes work and have them dialled into the models?”