I guess they really don’t have a full handle on the science and consensus after all.
NSF Releases Online, Multimedia Package Titled, “Clouds: The Wild Card of Climate Change”
Reader-friendly multimedia package covers the crucial but enigmatic role of clouds on climate change, and how scientists are defining that role
Clouds from an airplane over Michigan. |
November 4, 2010
View a webcast with David Randall, professor of atmospheric science at Colorado State University.
As discussions about climate change continue, one critical factor about this phenomenon has remained largely unknown to the public: the important but enigmatic role of clouds in climate change. The role of clouds is important because at any given time about 70 percent of the Earth is covered by clouds. The role of clouds is enigmatic because clouds can exert opposing forces: Some types of clouds help cool the Earth and some types of clouds help warm it. Which effect will win out as our climate continues to change? So far, no one is certain.
In order to help clear the air on clouds, the National Science Foundation is releasing an online multimedia package on the role of clouds on climate change, entitled, “Clouds: The Wild Card of Climate Change.” It addresses such pressing questions as, will clouds help speed or slow climate change? Why is cloud behavior so difficult to predict? And how in the world are scientists learning to project the behavior of these ephemeral, ever-changing, high-altitude phenomena?
“Clouds: The Wild Card of Climate Change” features:
- a live webcast with cloud and climate expert: David Randall, director of the Center for Multiscale Modeling of Atmospheric Processes and a professor of atmospheric science at Colorado State University;
- informative, easy-to-understand texts;
- eye-catching photos;
- a narrated slide show;
- dynamic animations;
- enlightening interviews with cloud researchers; and
- downloadable documents.
This package–which provides a wealth of information to reporters, policymakers, scientists, educators, the public and students of all levels–is posted on NSF’s website.
-NSF-
Stephen Wilde says:
November 6, 2010 at 10:17 am
CO2 as ‘kindling’ for the water cycle.
I like that. A very helpful metaphor, thanks.
Its a useful metaphor – but does it not imply positive feedback? George Smith who made the quote also distances himself from the implication of positive feedback, if I understand correctly.
Dave Springer says:
November 7, 2010 at 7:37 am
@phlogiston
Yes, the testimony of the geologic column is irrefutable. The much higher CO2 level in most of the past is what kept the earth green from pole to pole for tens or hundreds of millions of years at a stretch uninterrupted by ice ages.
Based on the palaeo timelines of CO2 and global temperature:
http://biocab.org/Geological_Timescale.jpg
I cant quite accept that over the last half billion years (the history of multicellular life), that CO2 and temperature are at all correlated. Both temperature and CO2 are now lower than in the Cambrian – but that is as much as you can say. Looking at the temperature line – it appears to seek two stable levels, about 12C and 22C globally. 22C appears to be the more stable, with a dip toward 12C regularly every 150 million years (Marinoan ice age 600 Mya, Saharan-Andean ice age 450 Mya, cold dip between Carboniferous and Permian 300 Mya, cold dip between Jurassic and Cretaceous 150 Mya, present cold dip and glacial period now). Of course the fly in the ointment is the prolonged fall in temperature during the tertiary epoch. But a bi-stable pattern is none the less discernable. (It has been suggested that the 150 My spaced cold spells are related to galactic rotation and cosmic ray / dust clouds.)
And this biphasic pattern bears no evident relationship to CO2 levels whatsoever. It is quite possible that CO2 plays no role in these temperature fluctuations.
The prediction based on this pattern is that sometime in the next 100 My or so we pop back up to 22C globally – with as you say rainforests at the poles. Regardless of CO2.
Just remember also – according to this paper by Franck et al – CO2 starvation – not overheating – will be the final cause of extinction of life on earth (see fig. 6) – worth remembering before getting too enthusiastic about removing CO2 from the atmosphere.
http://www.biogeosciences.net/3/85/2006/bg-3-85-2006.pdf
phlogiston says:
November 8, 2010 at 4:48 am
It’s a positive feedback (melting of ice and snow) that activates a negative feedback (evaporation and cloud formation).
Stephen Wilde says:
November 7, 2010 at 9:58 am
re; ice age regular cyclicity
Ice ages aren’t so regular. Interglacial/glacial periods during the most recent ice age are exhibit some regular cyclicity.
re; CO2 levels millions of years ago
I’m not sure but I don’t think the geologic column has the resolution to say whether CO2 leads or lags global temperature. All I know is that when CO2 levels were far higher than today, which is the case during most of the last half billion years, there were stretches of time measuring in the tens and hundreds of millions of years where there were no ice ages. Today we’re in an ice age that has persisted for about 3 million years with brief interglacial respites where the glaciers retreat to high northern latitudes only to return almost like clockwork. The current ice age is about tied for the deepest freeze in the last 500 million years where the other one this deep was over 400 million years ago.
It might be that orbital mechanics are at least partly responsible for the onset of major ice ages with cyclicity in the hundreds of millions of years. This would be the orbital mechanics of our sun in relation to the rest of the galaxy. Our solar system orbits the galactic center at a different rate then the spiral arms such that the solar system transits a spiral arm every couple hundred million years. The density of cosmic rays inside a spiral arm are much greater than outside due to the higher density of stars and hence higher density and proximity to supernovas. If the hypothesis that cosmic rays inhibit or accelerate high altitude cloud formation is correct then the short term cyclicity of the sun’s magnetic field which deflects more or less cosmic rays has a confounding factor which is a very long term cyclic change in the density of the rays it is defecting.
Continental drift must also play some role in very long time frames. Whether one or both poles are occupied or not by a continent would vastly change the mechanics of heat transfer. The poles are like a radiator in a car with ocean currents moving heat from the tropics to the poles. If a continent is blocking the warm current from reaching the pole it’s like your car radiator has a restriction in it which limits the flow which will of course cause the radiator to be cooler and the engine warmer than it otherwise would be. We can see this in the disparity in average temperature between the north and south poles today. The north pole is our most effective radiator today and the less difference in temperature between tropics and poles means the cooling system is working better.
From an engineering (always the way I look at things) viewpoint the melting of arctic ice cap has a negative feedback associated with it. Ice is a good insulator and albedo at the poles means little. A low angles of incidence water is a pretty good reflector of short wave (visible light) and at the poles insolation is minimal to begin with so surface albedo there changes little and on top of that there’s little to change. The interesting thing is that when the ice is gone so is the insulation which is hampering the escape of long wave energy from the surface to space. So as the ice cap extents and duration lessens the radiator performance improves. As the radiator performance improves the source of the heat (the tropical ocean) has heat removed from it faster. This is a negative feedback. Climate boffins believe this is a positive feedback entirely due to albedo change from ice (high albedo) to water (low albedo). But that’s just nonsense when you figure in the amount of insolation potentially changeable by polar albedo change and the inconvenient fact that water has a much higher albedo at low incidence angles.
Another negative feedback in this is the temperature differential between the tropics and the poles in relation to energy available to accomplish the work of moving warm water from the tropics to the poles. A larger temperature differential has a larger potential for producing work. So as the pole gets colder in relation to the tropics the heat pump has a greater potential energy source to move warm water from the tropics to the poles. As more water is moved the temperature gradient decreases and hence less energy available to accomplish the work.
CO2 is insignificant in this interplay as it’s well mixed and doesn’t change phase in the earth’s temperature range. It cannot be a working fluid for a heat pump as your working fluid gets the job done through phase changes. Water is a superb working fluid for heat pumps and heat engines in the phase change from liquid to vapor and vice versa due to it’s extreme latent heat capacity and non-extreme working temperatures.
It seems almost without doubt that orbital mechanics are what is currently tipping the earth in and out of interglacial periods but my question is what happened 3 million years ago that tipped the earth out of a warm period that had lasted for
@phlogiston
“it appears to seek two stable levels, about 12C and 22C globally”
12C appears to be about 8C too high for the cold side. The average temperature of the global ocean is 4C. The bulk of it lies below the thermocline at 3C while a shallow surface layer is predominantly much warmer until you get near the poles.
While mixing between the thermocline and bulk of the ocean is limited and in the short term driven by convection where the convective energy is supplied by the temperature gradient between tropics and poles in the longer term, such as the time it takes to complete one glacial/interglacial cycle, conduction should suffice to bring the water below the thermocline to the average of the surface temperature. Thus I consider it almost certain that the average temperature of the earth in during the last few hundred thousand years is 4C not 12C. Brrr… that’s pretty chilly.
@phlogiston
Actually I think the great attractor on the cold side is well below the average temperature of the moon if it weren’t for atmospheric CO2. The moon’s average temperature is -23C and its average albedo is near 15%. The earth receives exactly the same amount of insolation but when it gets cold its average albedo rises far higher than the moon due to being covered with ice and snow which of course means the equilibrium surface temperature would be far lower. This is where CO2 greenhouse effect becomes critical. In clear sky with dry air a mere 100ppm or so keeps the surface warmer by a calculated 30C or so which, in most times, is enough to spell the difference between being covered by liquid water and being covered by snow and ice.
Obviously it isn’t always enough as ice ages present well in the geologic column and we’re living in a deepest ice age of the last few hundred million years right now. Complaining about anthropogenic warming in the midst of an ice age seems to me to be something that could only be embraced by those who are grossly uninformed, in a state of denial, or have some vested interest in keeping the FUD (fear, uncertainty, and dread) surrounding the dumbass controversy alive and growing.
@Stephen Fisher
Snowball earth is a bit controversial but ice ages where glaciers cover the surface two miles deep down to at least 40 degrees north and south latitude are not. Volcanic activity over a long period of time I think is almost certainly what brings the earth out of an ice age. Ash cover lowers the albedo of snow & ice and CO2 emitted by volcanoes will also accumulate absent the normal sinks of ocean surface and green plants. CO2’s potential as a greenhouse gas is beyond credible dispute when it is unfettered in cold dry cloudless air. In warmer conditions it is fettered by the water cycle. Just as indisputable is its diminishing effectiveness as a greenhouse gas per unit increase in concentration. At the current concentration with the water cycle modestly active additional CO2 greenhouse warming can only be a good thing as it might be enough to break the earth out of the ice age. Less CO2 can only be a bad thing as it’s beyond dispute that the earth is and continues to be in an ice age that began about 3 million years ago is still getting colder with no end in sight. See here:
http://en.wikipedia.org/wiki/Timeline_of_glaciation#Known_ice_ages
@Stephen Fisher Wilde says:
November 7, 2010 at 6:29 pm
“I agree that we don’t have a complete solution but I’d rank the causes in order of length of timescale involved as astronomic then oceanic then solar.”
Astronomical is solar, whether at a daily scale, or glaciation cycles.
I get a feel for the oceanic effects by looking at how fast land temperatures can change, despite the heat capacity of the oceans.
“I think you favour planetary gravitational influences as the factor inducing the gross solar variation and that may be so but I don’t know either way.”
From what I am looking at, I would say it has to be electromagnetic, and nothing to do with barycenters or solar tidal effects.
On feedback:
When the garbage truck backs up to the edge of the landfill, and tips its load onto the side of a slope covered with previous loads of garbage, you can expect that that dumped truckload will bounce or roll or sink, or blow around, until it all reaches new locations and everything settles down. In the process garbage that had previously been dumped; will also get displaced; and find new locations; until all is quiet again; or the next truck load arrives.
That IS NOT FEEDBACK !!! All that is happening, is that everything is adjusting to a new condition once the existing stationary state is disturbed.
If you launch your boat onto the ocean; the sea level will rise. That is NOT FEEDBACK; it simply is a system readjusting itself to its new conditions.
When you add CO2 (extra) to the atmosphere; you don’t need all of the existing GHG molecules of all other species; to keep the atmosphere at the same temperature; and the abundance of every other species of GHG molecule in the atmosphere will settle on some new value; with pretty much the same total atmospheric heating effect. In the case of H2O where more H2O in the atmosphere menas less solar energy captured by the planet; a rise in CO2 will simply end up with evnutally more clouds. Who knows; eventually the ozone level would likely change as well as all the other various atmospehric reactions rattle aorund; just like that truck load of garbage that just got dumped on the landfill.
The difference between H2O and every other common GHG species, is that as a vapor, it has both surface cooling (absorbs sunlight) and atmospheric warming (absorbs sunlight, & also absorbs LWIR) effects; but once it forms clouds out of vapor, liquid, and solid phases, H2O takes planetary cooling to a new level.
H2O is the only player, that plays both for the offense, and the defence; HEY ; IT’S THE WATER !!
George,
At what level of cloud affects would increasing albedo causing a decrease in SWR reaching the surface of the ocean, overwhelm the atmospheric warming of increased LWIR in the atmosphere? In other words can high thin clouds cause a short term warming but a long term cooling due to reduced SWR impacting the oceans?
Dave Springer says:
November 8, 2010 at 8:15 am
It is annoying that the Nahle 2007 timeline figure for temp and CO2 is the absence of y axis values – thus I may have used the wrong numbers.
CO2 does trap heat of course, in a logarithmic relation to its concentration in air. However, in my view CO2’s most significant effect on climate is not this physical radiative balance effect, but in sustaining the biosphere. No CO2 – no life. The spread of photosynthesizing plants across land and sea brought down atmospheric CO2, and the land plants – particularly trees – mixed humates into the weathered silicates (from glaciations) to give us soils and trap more water on land, extending the hydrological cycle. Over the sea also sulphides emitted by plankton nucleate clouds and further accellerate the hydrological cycle.
Thus the big fall in both temperature and CO2 from the Cambrian to the Carboniferous does not prove CO2 causality – I believe the primary mechanism was extension and accelleration of the hydrological cycle over (previously arid) land. A nice paper by Beerling and Berner 2005 showed that transiently there was a positive feedback between evolution of more efficient trees and leaves and falling CO2.
http://www.pnas.org/content/102/5/1302.full.pdf+html
Separating a small effect (CO2 on global temperature) from a big effect (hydrology on global temperature) is difficult analytically – like in the medical field separating a handful of radiation induced cancers epidemiologically from thousands of “background” naturally occurring cancers.
But looking at the whole picture, I agree fully with you that the case does not really exist for claiming catastrophic consequences (FUD etc.) of rising CO2 concentration from trace levels. The effects on the biosphere of rising CO2 (plants will evolve to exploit more abundant CO2) could well be greater than direct physical effects on radiative balance.
“”””” david says:
November 8, 2010 at 7:30 pm
George,
At what level of cloud affects would increasing albedo causing a decrease in SWR reaching the surface of the ocean, overwhelm the atmospheric warming of increased LWIR in the atmosphere? In other words can high thin clouds cause a short term warming but a long term cooling due to reduced SWR impacting the oceans? “””””
Well David, I am not sure that I exactly understand your question.
First off, I presume that you DO understand that ANY H2O vapor in the atmosphere WILL block (some) sunlight from reaching the surface (by absorbing it); and maybe 20% of the Total solar spectrum energy is available to be absorbed by H2O vapor. (over the spectral region from about 750 nm to 4.0 microns. Only 1% of solar energy arrives beyond 4.0 microns.
I presume you also understand that ANY increase in H2O vapr in the atmosphere WILL result in more absorption, and even less sunlight reaching the surface; and we are not talking about here today; gone tomorrow; we mean amounts and changes, that persist for climae meaningful times. I’d be happy even with one full trip around the sun.
Then we come to clouds. I presume you understand that ANY cloud will reflect SOME sunlight off the tops back out into space. (albedo); and bear in mind that now we are talking about the WHOLE solar spectrum containing significant energy. Clouds scatter and “reflect”most of the visible range; so a lot more than just the 20% that water vapor could capture. And I assume you understand that ANY increase in clouds will reflect EVEN MORE sunlight back into space. Also I assume you understand that those same clouds will absorb additional sunlight so it doesn’t reach the ground; and that more clouds will absorb even more sunlight.
So any way you want to skin the cat; water in the atmosphere in any and all phases WILL reduce the ground level solar energy; and MORE water, WILL mean LESS solar energy at the ground.
Now the albedo reflections from the clouds are simply lost solar energy; end of story. The atmospheric water absorptions WILL warm THE ATMOSPHERE. The atmospheric warming caused by absorbed SOLAR ENERGY; will result in LWIR emissions; about half of which will reach the surface and MAY warm it; BUT not as much as would have the ORIGINAL solar energy that was intercepted.
NOW THAT is ALL the warming energy there is in the system (neglecting geo-thermal which is miniscule). There is NO OTHER significant source of energy input; it all comes from the sun. (I can just see all the ambulance chaser nit picking lawyers lining up their exceptions).
Now what about the LWIR thermal radiation emitted from the earth surface; and that emitted from the atmosphere. We already explained that a part of the atmospehric LWIR thermal emission is due to the original solar energy absorbed by the water vapor and clouds.
THE REST OF IT CANNOT warm anything. The surface, and the atmosphere, and the clouds are simply swapping that LWIR energy back and forth between themselves; but it is slowly being DISSIPATED to space.
So the most you can say is that the atmospehric absorption of LWIR can and does slow down the cooling of the surface; but it cannot warm the surface. ONLY the SOLAR INPUT can warm the surface; and no matter how you slice it; water in the amosphere can only reduce the amount of solar energy and warming that the earth receives from the sun.
As to the height of the clouds. The sun is a near point source (to some people); specifically it has an angular source diameter of 30 minutes of arc; 1/2 degree. So a cloud casts a shadow, with a 1/2 degree penumbral edge on it. You can see these shadows on the ground from an aeroplane so they are quite real. So a one square km cloud casts a one square km shadow on the ground; and inside that shadow, the surface solar irradiance (W/m^2) is reduced. That same ground shadow zone is also reflecting some sunlight, and emitting some LWIR thermal radiation. Except for a calm water surface, both the reflection and the emission have at least a Lambertian . That is the Radiant intensity varies as Cosine of the angle off normal.
I = Izero.Cos (theta). (Watts per Steradian) We can show that the total energy is simply pi.Izero Watts. Now if we wanted to factor in the area; we would start with the Radiance, in Watts per m^2 per steradian; and we would end up with Watts per m^2 for total Emittance. In this case the Radiance is independent of angle; since the projected area also changes as Cosine(theta).
Now that is the best case. Since the earth surface is quite rough; each surface element radiates in a Lambertian pattern; but the surface orientation is random; so the end result is that the radiation pattern is isotropic.
The point is that whereas the cloud shadow is essentially the same size as the cloud; the emitted LWIR from that area WILL illuminate THE ENTIRE SKY; and out of that entire sky area our cloud is one square km; and it will intercept very little of the LWIR emission from that shadow zone; most of it will escape the cloud. And the higher the cloud is; the less of that surface emission it will intercept.
And what of the LWIR that the cloud DOES intercept. Well some may be reflected again; and some will be absorbed; and subsequently re-emitted; and in both cases; those emissions too, will be at least Lambertian, and more likely isotropic; and the amount of that which returns to our shadow zone is going to be minute in the extreme.
Well actually it will fall off (for the round trip) as 1/H^4 where H is the cloud height; and then there is an obliquity factor of Cosine^8(theta) For 30 degrees off normal, the obliquity factor is about 32%; for 60 degrees off normal it is 3.9%.
Now don’t let the quickness of the hand deceive the eye. We must not forget; that every other spot outside our shadow zone is also emititng LWIR and reflecting sunlight. Each of those elemental areas will have its own cloud height and obliquity factor; so the cloud will receive a lot more LWIR than just from our shadow; BUT on the return trip; when the cloud radiates to the surface; we still have a full 1/H^2, and a cos^4(theta) obliquity, and that cloud radiation will be spread over the entire surface.
But remember that this is just a redistribution of energy which has already been acccounted for in the original solar input.
And no matter what; the clouds; and more clouds will mean less; and even less total energy captured by the earth from the sun; and it WILL cool down. The GHGs just slow the cool down process; but they DO NOT prevent it.
George, thank you for taking the time to write this, and yes I do follow it. One point you have not addressed as directly as I am hoping to understand is in my question, “In other words can high thin clouds cause a short term warming but a long term cooling due to reduced SWR impacting the oceans?” Your answer is in the affirmative, but not at all quanative.
The orthodox view is that the increased residence time of LWIR within the atmosphere due to increased GHG overwhelms the decrease in SWR reaching the ocean surface when compared on a WM/2 basis, and somehow this increased atmosphere temperature and LWIR somehow warms the ocean, creating an additional warming over a decade or longer lag effect and that feedbacks such as high clouds amplify this warming further.
On the other hand your presentation appears more intuitive to me. However I have seen neither scenario quantified on a WM/2 basis along with an analysis of the radiative spectrum effects that appear critical to me. So, (please forget the inaccuracy of my any numbers, they are illustrative only) the high thin clouds that “climate scientist” consider to have a net warming on the planet, (atmosphere, earth and ocean), change the incoming TSI from what spectrum and WM/2 to what spectrum and WM/2 at the OCEAN surface, and further how does this DECREASE in SWR affect the ocean LONG TERM even though there is a rapid increase in atmospheric temperature due to LWIR bouncing all around before finally leaving?
My questions are awkwardly formatted because I am not a scientist so please understand the poorly worded structure and ignore the numbers. Perhaps a more simple assertion would be something like this. High thin clouds, which produce an ocean surface REDUCTION of 5 WM2 SWR in these spectral WL, have greater long term cooling of the planets heat content then the increase in LWIR in the atmosphere which achieves a temporarily higher atmospheric radiative balance until the oceans radiative balance equalizes to a cooler temperature, which then reduces the LWIR from the surface, counteracting the temperature rise from the increased residence time of LWIR due to increased GHGs.
Or to really shorten the assertion” Over X time a reduction of 5 WM/2 of SWR at the ocean surface negates 10 WM/2 increase in LWIR in the atmosphere. (Again the numbers are merely illustrative.)
Now I know there are many other factors, the ones you mention, an increase in all clouds, the speeding of the hydrologic cycle, the increased biomass which has a CO2 reducing lag effect via absorbing more CO2 as the biomass increases, latitude shifts in jet streams and therefore cloud cover, etc, but the different long term effects of changes in the radiative spectrum is what I am trying to understand and I think the oceans and how they absorb radiation have everything to do with this. As you say, “The GHGs just slow the cool down process; but they DO NOT prevent it.”
Thanks for your time, the layman’s understanding is greatly increased by sites such as this when we take the time to understand.
Hell George, let me make the assertion really simple, One SW photon in the ocean is worth two IR photons in the atmosphere. (Only the real numbers need to be quantified). (-:
“”””” david says:
November 11, 2010 at 3:07 am
George, thank you for taking the time to write this, and yes I do follow it. One point you have not addressed as directly as I am hoping to understand is in my question, “In other words can high thin clouds cause a short term warming but a long term cooling due to reduced SWR impacting the oceans?” Your answer is in the affirmative, but not at all quanative. “””””
Well David, my stick for scratching in the sand; contains NO memory chips; so I can only scratch about stuff that I can remember in my gray, and ever graying matter.
I do have access to some very ancient but extensive text book data; but very little to much current work. But from time to time a lot of the regulars here publish links to all sorts of really interesting stuff.
As to your question; I am not sure that I can agree with the premise. I don’t buy the climatism 101 mantra that high thin clouds warm the earth up and so are a positive feedback.
You see the choice is; will the earth (the whole thing) get warmer without those high thin clouds; or with them.
So my experimental grant money would be spent measuring the global temperature without clouds over some useful time scale; and then adding in those high thin clouds to observe whther the temeprature now goes up or down; surface temperature that is.
And I simply can’t find any Physical mechanism that would cause the Temperature to go up.
Suppose for example that the earth surface; and the clouds had a very high and specular reflectance for LWIR as if they were two plane mirrors (well large radius curved mirrors); which they certainly don’t. Now we won’t make them perfectly reflecting; say 95% for a start. I don’t care if we call it 95 or 99 or 99.9; just not 1.0 reflectance.
So the ground will absorb some of the LWIR energy falling on it; 5%, and for the time being we won’t get intot what happens to that; we just assume that it goes into the earth and stays there.
Likewise the cloud doesn’t reflect everything; it absorbs 5% too.
Now both the cloud and the surface are also emitting LWIR Thermal radiation just because of their Temperatures, and that is what is rattling around back and forth between the two highly reflective layers.
As a result of the 5% that is absorbed at each end, the cloud or surface will re-emit some more thermal LWIR radiation. But that radiation is emitted isotropically; and in the case of the cloud; only half of it will go back down to the surface, and the rest is lost to space. Likewise the surface emits some of that energy but the rest is conducted into the earth.
So we have a sort of resonant cavity, with LWIR radiation bouncing back and forth between the two “mirrors”; BUT with that inexorable continuous loss through the mirrors to get removed from the cavity.
So absent any new energy input, this radiation filled cavity can only cool down. There is no process by which its Temperature could go up; since it is constantly losing energy.
Well of course the initial input of energy to this system can only come from the sun, as short wave, or at least solar spectrum radiant energy; and no matter how long it takes the cavity to “ring down” as they say (depending on its Q), it will ring down and lose energy and can only be heated up again by input of solar energy, and the more water vapor, and the more clouds of any sort in the sky the less of that soalr energy that can get into the cavity to heat it to tis operating temperature; it MUST cool down.
Now I chose to make the mirrors high reflectance like those of an Optical Fabry-Perot Etalon; but in reality, they aren’t anywhere near as good as that, and in addition to being lower reflectance; they are also highly scattering or diffuse in their radiation patterns.
And I believe that the key to understanding this, is to realize that those high wispy clouds are the RESULT of the warmer muggier surface conditions during the day; which will rise during the night and form those clodus. The clouds are NOT the CAUSE of the warm balmy daylight conditions.
As to radiation levels; the TSI is 1366 W/m^2 extra-terrestrially, and maybe 1000 W/m^2 at the surface with average atmospheric water contents (vapor) and assuming no clouds. Of that over 70% arrives over tropical oceans; and about 97% of that is absorbed quite deepluy in the ocean 10s to 100s of metres. For terra firma terrains the absorption and reflectances are quite diverse; and one problem is that they vary wildly from solar spectrum wavelengths to the LWIR wavelenghts which are typically 20 times longer. So the hard surface picture is much more complex; but also deals with less than 30% of the area, and somewhat less than that of the total solar energy input.
You see I’m not too concerned about what exactly all those other W/m^2 numbers are; because I don’t think it matters; except in the details.
The picture which I find completely inescapable; is that the water evap/condensation/precipitation cycle is in firm and complete negative feedback control of a robust stable system; and CO2 doesn’t have much to do with it.
And for the legal disclaimer; NO I do not believe that CO2 is not a GHG that absorbs LWIR and warms the atmosphere; it is and it does; mox nix because H2O puts the kibosh on any of that.
Don’t know if anyone’s still reading this. Primary benefit of clouds is that they cool the earth by carrying heat up in water vapour, high heat storage capacity, conductivity, without this we’d have desert conditions globally, as we have locally (+20-30degrees C global estimate). CO2 can only join in the cooling, and the rest of cycle, the distribution of water and food for life.
Can’t do the link, but google books Oceanography:an invitation to marine science By Tom Garrison Page 161 for the amazing properites of water.