Guest Post by Willis Eschenbach
Well, in my last post I took a first cut at figuring the cloud radiative “feedback” from the CERES dataset. However, an alert commenter pointed out that I hadn’t controlled for the changes in solar radiation. The problem is that even if the clouds stay exactly the same, if the solar radiation increases, the net cloud radiative effect (CRE) increases due to increased reflection … and I hadn’t thought about that, had I? Dang … so my post was wrong.
So, to control for solar radiation, I did a multiple linear regression. The dependent variable was the net CRE, and the independent variables were the surface temperature and the solar radiation. As you might expect, this gave smaller results than my first analysis. I believe that this method is correct, but I’m always willing to be shown wrong. Not happy to be … but willing to be.
Figure 1. Net CRE as a function of surface temperature, after controlling for solar radiation. The gray lines are contour lines at zero W/m2 per °C. I suspect that the blue around Antarctica is an artifact due to the presence of the sea ice edge.
Note that there are several areas in the tropical oceans which have a strong negative change in radiation with respect to temperature. These are the areas of the Inter-Tropical Convergence Zones, about ten degrees both north and south of the Equator. It is in these areas that much of the regulation of global temperature takes place, by means of the combined effect of cumulus clouds and thunderstorms.
In addition, there is a large area of the Southern Ocean where the clouds oppose the temperature rise.
The area of clouds off of the coast of California and northern Mexico is an area of persistent stratus that also strongly opposes warming. (See here for a discussion of this location in the literature).
Finally, I note that the global average change in net cloud radiation for each degree of surface warming is positive, at 0.7 W/m2 per degree. On reflection, it seems to me that we need to compare that to how much we’d expect the cloud radiation to increase if the surface temperature goes up by 1°C.
And I don’t know the answer to that … still pondering on that one.
Finally, it’s worth bearing in mind that the radiative effect of clouds is only the beginning of a long list of ways that clouds cool the surface. These include:
• Physically transporting heat from the surface directly to the upper troposphere where it radiates easily to space. Since the heat is transported either as latent heat, or as sensible heat inside the thunderstorm tower, it doesn’t interact with the large amount of water vapor, CO2, and other GHGs in the lower atmosphere.
• Wind driven evaporative cooling. Once the thunderstorm starts, it creates its own wind around the base. This self-generated wind increases evaporation in several ways, particularly over the ocean.
a) Evaporation rises linearly with wind speed. At a typical squall wind speed of 10 mps (20 knots), evaporation is about ten times higher than at “calm” conditions (conventionally taken as 1 mps).
b) The wind increases evaporation by creating spray and foam, and by blowing water off of trees and leaves. These greatly increase the evaporative surface area, because the total surface area of the millions of droplets is evaporating as well as the actual surface itself.
c) To a lesser extent, surface area is also increased by wind-created waves (a wavy surface has larger evaporative area than a flat surface).
d) Wind created waves in turn greatly increase turbulence in the boundary layer. This increases evaporation by mixing dry air down to the surface and moist air upwards.
e) Because the spray rapidly warms to air temperature, which in the tropics is often warmer than ocean temperature, evaporation also rises above the sea surface evaporation rate.
• Wind driven albedo increase. The white spray, foam, spindrift, changing angles of incidence, and white breaking wave tops greatly increase the albedo of the sea surface. This reduces the energy absorbed by the ocean.
• Cold rain and cold wind. As the moist air rises inside the thunderstorm’s heat pipe, water condenses and falls. Since the water is originating from condensing or freezing temperatures aloft, it cools the lower atmosphere it falls through. It also cools the surface when it hits. In addition, the falling rain entrains a cold wind. This cold wind blows radially outwards from the center of the falling rain, cooling the surrounding area.
• Increased reflective area. White fluffy cumulus clouds are not tall, so basically they only reflect from the tops. On the other hand, the vertical pipe of the thunderstorm reflects sunlight along its entire length. This means that thunderstorms shade an area of the ocean out of proportion to their footprint, particularly in the late afternoon.
• Modification of upper tropospheric ice crystal cloud amounts (Lindzen 2001, Spencer 2007). These clouds form from the tiny ice particles that come out of the smokestack of the thunderstorm heat engines. It appears that the regulation of these clouds has a large effect, as they are thought to warm (through IR absorption) more than they cool (through reflection).
• Enhanced nighttime radiation. Unlike long-lived stratus clouds, cumulus and cumulonimbus generally die out and vanish as the night cools, leading to the typically clear skies at dawn. This allows greatly increased nighttime surface radiative cooling to space.
• Delivery of dry air to the surface. The air being sucked from the surface and lifted to altitude is counterbalanced by a descending flow of replacement air emitted from the top of the thunderstorm. This descending air has had the majority of the water vapor stripped out of it inside the thunderstorm, so it is relatively dry. The dryer the air, the more moisture it can pick up for the next trip to the sky. This increases the evaporative cooling of the surface.
Finally, since they are emergent phenomena that only arise where the surface is warmer than its surroundings, clouds and thunderstorms preferentially cool mainly the warmer areas in a way which is not well represented in bulk averages. In other words, the averages of the bulk measurements of say temperature and relative humidity in a gridcell containing thunderstorms gives little idea of the high-speed movements of massive amounts of energy which are taking place.
Anyhow, that’s take two on the CRE … I’m still ruminating on what I can learn from the CERES data, it’s far from mined out.
Best to all,
w.
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Willis,
Your list of mechanisms that cool the surface (such as Cold rain and Cold wind) add energy to the atmosphere. Condensation in clouds adds a LOT of energy to the air. Of course, you maintain that this energy is more easily transmitted to space, which I believe is true. Just a semantic use of the term “surface”. I guess the question would be how much more efficient is the radiation of energy from the upper atmosphere as a result of this added ‘heat’ as compared to the decrease in radiation from the surface due to its loss of ‘heat’. Oh, and sorry for the use of the term ‘heat’ as a synonym for temperature increase or energy.
Willis says: “On reflection, it seems to me that we need to compare that to how much we’d expect the cloud radiation to increase if the surface temperature goes up by 1°C.”
Hi Willis. Haven’t you answered your own question in the preceding sentence?
“Finally, I note that the global average change in net cloud radiation for each degree of surface warming is positive, at 0.7 W/m2 per degree. “
So comparing the 0.7W/m^2 to the 0.7W/m^2 seems to be a bit of a “Tada” moment.
This is getting to be funny. Every now and then (but amazingly frequently…), Willis sits down for a few hours and actually does effective science on a CAGW (or what ever we’re calling it this week) topics of interest.
Geez – if I was one of the hoard of IPCC enthusiastic fools, this would be downright embarrassing. I sure wouldn’t want my mom to know I was so ineffective that some guy named Willis sits in his den and does more and better work than my entire IPCC crowd of hundreds of scientists, economists, psychologists, train engineers, tree surgeons, etc does in 4-5 years.
Keep up the good & interesting work, Willis.
Willis, I believe you might have missed one important radiative effect that I believe dominates the short term balancing act that water in its many forms contributes as the planets heat governor. You came close when you mentioned the effect of “Physically transporting heat from the surface directly to the upper troposphere . . . ” in latent heat and sensible heat, where it can be radiated out to space . . . but the pertinent question is how? How does water carry and then very rapidly radiate a disproportionate amount of energy back to space as compared to other gases?
I believe you are right on the money concerning latent heat. Water does have an enormous heat capacity, but when you take into account the massive energy consumed during phase transitions, the enthalpy of vaporization, ” 40.65 kJ/mol, is more than five times the energy required to heat the same quantity of water from 0 °C to 100 °C (cp = 75.3 J K−1 mol−1) (WIKI). Likewise, the enthalpy of fusion of water and enthalpy of sublimation are far greater for water than for any other naturally circulating gas or liquid, (except perhaps ammonia). For water these numbers tell the whole story:
Melting: -79.7 cal/g, -330,000 J/kg
Evaporation: -597.3 cal/g, -2,500,000 J/kg
Sublimation: -677.0 cal/g, -2,830,000 J/kg
Freezing: +79.7 cal/g, +330,000 J/kg
Condensation: +597.3 cal/g, +2,500,000 J/kg
Deposition: +677.0 cal/g, +2,830,000 J/kg
Those enormous amounts of energy are absorbed by water at the sea surface, then water physically transports the energy up to the first cloud layer where condensation occurs.
So what did you miss? Well, in addition to cooling the gases around it, I believe the very process of condensing gives off IR radiation. Likewise when sufficient energy is still contained in the liquid water droplets that are billowing higher and higher into the cloud tower – when these water droplets hit the second layer of the atmospheric ocean and freezing occurs, then a second massive round of energy release occurs. So I believe thunderheads must glow even brighter at their pinnacle because of all the IR radiation that is given off by these phase transitions.
I first suspect that IR energy is directly given off by the phase transitions when I saw IR images of Sandy from space at night. The fact that there was “detail” in the images suggested to me that some clouds were actively irradiating (condensing and freezing) while others not so much. The second clue came when I watched the lecture by Gerald Pollack explaining his theory of liquid crystal water. During that explanation he mentions that water droplets take in IR energy to form the thin liquid crystal layer on their surface. So my thought was, if the process works one way, why not the other. Once the water is transported to a layer where the structure that it finds itself in can no longer support its current physical state, it must give off the energy to change state the same way it got it.
I believe the bottom layer of clouds (condensation) and the layer that forms the “anvil” in thunder clouds (freezing) are powerful IR radiation sources and glow quite brightly. In addition all of the electrical energy that the liquid crystal layer creates is rapidly released in ENORMOUS amounts in the form of lightning. . . visible light . . . brighter than the brightest sunlight.
What do you think?
Your mention that clouds are emergent phenomena leads to one more way clouds lose heat from the climate system. Systems with nonlinear emergent pattern export entropy. With cloud this means heat loss to space. The system’s own entropy decreases on account of the emergent structure. This is one aspect of Ilya Prigogine’s nonlinear thermodynamics.
Don’t trees have the same effect on land surface temperatures as clouds have on the oceans. When land was covered by enormous woods most of the solar radiation did not reach the surface because it was absorbed by the leaves what makes day temperatures colder and keeps night temperatures warmer.Clouds also form more easily over forest what makes the effect even bigger. Cutting down these big extensions of forest ( ship building) must have had a some influence on temperature. Great Britain had nearly no forest left because of this.
What is measured by the CERES dataset?
What does it not measured?
You have shown us (I think) the gridded slope of the best fit through 120 months of CERES, land, and SST data. How good it the fit for each grid cell?
Could we see a sample of cross plots at a selection of grid cells on a North-South traverse, say along longitude 180 or 150W or 150E. every 10, 12, or 15 deg latitude?
I also forgot to mention the additional theory that perhaps once cloud dropets form they become IR ‘sinks’. That is that they absorb a disproportionate amount of IR energy to form the “liquid crystal” layer that also creates their surface charge. This surface charge is what keeps clouds “organized” and billowing. So not only do clouds have a higher visible light albedo because they are natural white light prisms, but they are also IR “scavengers” and prevent IR from penetrating to the surface. What sort of make sense is that a disproportionate amount of the radiation that they give off during condensation is either radiated disporportionately out to space (because of the high concentration of water vapor ascending vertically below the condensation event) or is absorbed to form the liquid crystal layer by the droplets immediately adjacent to them. Only the droplets on the top surface of the billowing cloud actually have their IR irradiance propagate unrestricted to space. Any IR irradiation given off in any direction other than UP is “scavenged” by water’s HUGE energy capacity in the IR portion of the spectrum.
DONV,
I have a pet theory that the dust paricles in the water droplets are actually the IR radiators, which is why they promote condensation. I believe the dust particles function very much like the doping elements in plastic scintillators.
Willis,
I thank you again for your good work and open mind.
I just came across your website AND the website regarding global cooling!!
http://gnosis474.blogspot.com/2009/12/fiction-of-climate-science.html
When the USAF flew planes above and below the cloud deck taking simultaneous measurements,they found that clouds were absorbing different amount of energy than theory said they should. And I’m not talking about a few tenths of a W/m^2 here or there. More like a couple of dozen W/m^2
Anyone interested in this subject really needs to read this paper.
http://tallbloke.files.wordpress.com/2012/11/cess.pdf
http://gnosis474.blogspot.com/2009/12/fiction-of-climate-science.html
I find the discussion of this, and Willis’s first take: http://wattsupwiththat.com/2013/10/03/the-cloud-radiative-effect-cre/#more-95082 fascinating and informative, and I cannot help but compare this against the story that Popular Science has closed its comments because “debating science is dangerous”: http://joannenova.com.au/2013/10/popular-science-stop-comments-because-debating-science-is-dangerous-readers-are-dumb/#more-30899
Here this delightful discussion is speeding development and ideas along, and we’re all learning something, including Willis, who is giving us a prime example of what science is all about… while over there in consensus-land… well, there’s just nothing. No thought, no open-mindedness, no science in any form.
I mean, heck, if you want SCIENCE, it’s clear where you have to be.
A huge thank you, Willis, for demonstrating so clearly how a true scientist thinks and behaves and advances, and also why debate and discussion is so very important, and fun, and educational, and exciting, etc. I’m loving this. 🙂
Thank you tallbloke for the link.
1. I wonder if anyone has taken an IR spectrum of the top of large cumulonimbus in the tropics. This should give some credence or falsify my pet theory that dust particles are acting as radiators..
2. In my pet theory I would expect dust in water droplets, heated by condensation of water vapor and conduction, to act like black body radiators, allowing some wavelenghs to bypass the many adsorption bands of water, especially in the longer wavelengths.
Otsar: You’re welcome. Some more discussion of Mie scattering and cloud optical oddities here:
http://tallbloke.wordpress.com/2010/11/14/alistairmcd-aerosols-cause-warming/
“Mie solved Maxwell’s equations for a plane wave so the assumption of constant ‘Mie asymmetry factor’ is correct only when light first enters a cloud. Also, substantial direct backscattering at the upper cloud boundary is ignored yet it has an opposite dependence on droplet size than diffuse scattering. Therefore, above a threshold ‘optical depth’, pollution causes a reduction of albedo, another form of AGW. So, at the very least, the IPCC’s predictions of CO2-AGW should be reduced by a factor of about three, possibly much more if ‘cloud albedo effect’ heating explains most recent warming.”
Along with Roy Spencer’s new post we can be sure clouds will e keeping us guessing for some time to come.
If you wish someone to look over your theories, stats viewpoint, I’m happy to collaborate.
David
Willis
Compliments on your explorations.
To separate out cause and effect, may I suggest exploring the time lag between solar insolation and surface temperature. This should vary annually with latitude from south to north. See
Key Evidence for the Accumulative Model of High Solar Influence on Global Temperature David R.B. Stockwell
Stockwell finds Pi/2 (90 deg) or 2.75 year lag between the 11 year solar cycle and surface temperatures. I expect similar lags from annual variations varying with latitude with opposite phase between northern and southern hemispheres. That will also give you N-S graduations in the lag magnitude. Are there corresponding variations in your cloud radiation effects with phase lags during the year?
Could greater cloud cover in summer make it cooler as opposed to greater cloud cover in winter make it warmer?
Willis,
I believe there may be some benefit in expanding your examination of “emergent phenomena”. It is not just clouds that can be viewed in this way but also the breakaway of surface airmasses as their Raleigh number is exceeded each dawn and intermittently during the day.
The Raleigh Bernard circulation in the Hadley, Ferrel and Polar tropospheric convection cells could be compared to film running through an old 35mm projector. It runs smoothly past the sound pick up (near the tropopause) but stutters past the projection gate frame by frame (air masses breaking away from the surface during the diurnal cycle).
This circulation, including the transport of water vapour, is the primary mechanism for transporting energy high above the level of maximum IR opacity, where it is then radiated to space.
Increasing the concentration of radiative gases in the atmosphere will decrease the Raleigh number for airmass breakaway and increase the general speed of tropospheric convective circulation.
Increasing the concentration of radiative gases in the atmosphere will increase radiative cooling at altitude, and decrease the time to airmass subsidence.
Increasing the speed of tropospheric convective circulation will increase the speed of mechanical energy transport from the surface.
PS. – You mentioned the high altitude ice clouds causing warming claim. It is worth re-examining those papers. The proposed warming mechanism was ice crystals reflecting IR back to the troposphere, reducing radiative cooling of airmasses at altitude, increasing the time to subsidence, slowing the speed of tropospheric convective circulation and decreasing the speed of mechanical energy transport from the surface. I think you may be able to see why those papers had to be quietly forgotten 😉
I admire your efforts, but the following isn’t found in any meteorology text book.
“The air being sucked from the surface and lifted to altitude is counterbalanced by a descending flow of replacement air emitted from the top of the thunderstorm. This descending air has had the majority of the water vapor stripped out of it inside the thunderstorm, so it is relatively dry.”
(In addition to my last question)
I understand we have more cloud cover both summer and winter from cosmic rays as proven by the CERN Cloud experiment.
The real problem with all this completely logical conjecture is that it will never penetrate the unreasoning dogma of the climate CAGW religion . . . primarily because this theory begins with the assumption that the system is constantly striving to “balance” the energy imbalance. And that therefore, when you integrate underneath the instantaneous energy transfer curve on a second by second basis you don’t come up with a “temperature average”. Even CERES data set is an “average”. The energy released in any given thunderstorm, heck even during one lightning strike is never factored into the “average”. The bottom line is “average air surface temperature” is a terrible indicator of the earths net energy balance act, even when measured, then averaged, and homgenized and averaged again. A better measure would be to integrate the area under the curve on minute by minute basis of the relative humidity at each of the three layers of the atmospheric ocean for any given reporting period.
Look again at the picture at the top of WUWT! See the clouds? See the very very bright reflection off the clouds? See the huge thunder head? See the shadow it casts? What would this picture look like in the IR? Can you get any meaningful measure off of such a picture when you consider that it is actually a motion picture and that the reason for that thundercloud is that the atmospheric ocean in that particular location is very much “unbalanced” and is in the process of rebalancing.
I believe that unfortunately all Willis has done here is create a map, through careful billiant mathematical analysis that show the average distribution of thunder storms across the globe.
Good post. Thank you.
I liked your list of mechanisms whose quantitative effects are poorly characterized. Skeptics are accused on not knowing “the science” (or “the physics”) but you are adept at highlighting physical processes known to exist that are poorly known.
Otsar: Intersting theory. I agree that in order for condensation to occur in a “supersaturated system” some sort of seed is necessary to trigger droplet formation, but I think that dust is not as large a player as energetic particles bombarding the planet from outer space are. Look at Willis’s map. The Sahara generates more atmospheric “dust” than any other large land mass IMHO. Yet just to it’s west you see a large “blue” area? What’s going on there? Yet lower dust generated clouds represented by the thunderstorms coming off of the west of South America have much higher IR. Why the disparity?