Guest Post by Willis Eschenbach
My thanks to Nick Stokes and Joel Shore. In the comments to my post on the effects of atmospheric black carbon, Extremely Black Carbon, they brought up and we discussed the results of Ramanathan et al. (PDF, hereinafter R2008). Black carbon, aka fine soot, is an atmospheric pollutant that has been implicated in warming when it lands on snow. However, despite many claims to the contrary, atmospheric black carbon cools the surface rather than warming it.
There is an important implication in Ramanathan’s work regarding the canonical claim of AGW supporters that changes in surface temperature slavishly follow changes in forcing. Their claim is that the change in surface air temperature ( ∆T ) in degrees Celsius is a constant “lambda” ( λ ) called the “climate sensitivity” times the change in forcing ( ∆F ) in watts per square metre (W/m2). Or as an equation, the claim is that ∆T = λ ∆F, where lambda( λ ) is the climate sensitivity.
In R2008 they discuss the effect of black carbon (BC) on the atmosphere. Here’s the figure from R2008 that I want to talk about.
Figure 1. Figure 2C from R2008 ORIGINAL CAPTION: BC [black carbon] forcing obtained by running the Chung et al. analysis with and without BC. The forcing values are valid for the 2001–2003 period and have an uncertainty of ±50%. [Presumably 1 sigma uncertainty]
This figure shows the changes in forcing that R2008 says are occurring from black carbon forcing. Here is R2008’s comment on Figure 1, emphasis mine:
Unlike the greenhouse effect of CO2, which leads to a positive radiative forcing of the atmosphere and at the surface with moderate latitudinal gradients, black carbon has opposing effects of adding energy to the atmosphere and reducing it at the surface.
R2008 also says about black carbon (BC) that:
… as shown in Fig. 2, for BC, the surface forcing is negative whereas the TOA forcing is positive (Fig. 2c).
What are the mechanisms that lead to that re-partitioning of energy between the atmosphere and the surface?
Before I get to the mechanisms, I want to note something in passing. R2008 says that the forcing values have an uncertainty of ± 50%. That means the “Atmosphere” forcing is actually 2.6 ± 1.3 W/m2, and the “Surface” forcing is -1.7 ± 0.85 W/m2. This means that there is about a 30% chance that their “TOA” forcing, which is atmosphere plus surface, is actually less than zero … just sayin’, because Ramanathan didn’t mention that part. But for now, let’s use their figures.
PART I – What’s going on in Figure 1?
According to R2008, atmospheric black carbon causes the surface to cool and the atmosphere to warm. The surface is cooled by atmospheric black carbon through a couple of mechanisms. First, some of the sunlight headed for the surface is absorbed by the black carbon, so it doesn’t directly warm the surface. Second, any sunlight intercepted in the atmosphere does not have a greenhouse multiplier effect. Together, they say these effects cool the surface by -1.7 W/m2.
The atmosphere is warmed directly because it is intercepting more sunlight, with a net change of + 2.6 W/m2.
R2008 then notes that the net of the two forcings, 0.9 W/m2, is the change in the top-of-atmosphere (TOA) forcing.
The authors go on to say that because black carbon (BC) has opposite effects on the surface and atmosphere, the normal rules are suspended:
Because BC forcing results in a vertical redistribution of the solar forcing, a simple scaling of the forcing with the CO2 doubling climate sensitivity parameter may not be appropriate.
In other words, normally they would multiply forcing times sensitivity to give temperature change. In this case that would be 0.9 W/m2 times a sensitivity of 0.8 °C per W/m2 to give us an expected temperature rise of three-quarters of a degree. But they say we can’t do that here.
This exposes an underlying issue I want to point out. The current paradigm of climate is that the surface temperature is ruled by the forcing, so when the forcing goes up the surface temperature must, has to, is required, to go up as well. And vice versa. There is claimed to be a linear relationship between forcing and temperature.
Yet in this case, the TOA forcing is going up, but the surface forcing is going down. Why is that?
To describe that, let me use something I call the “greenhouse gain”. It is one way to measure the efficiency of the poorly-named “greenhouse” effect. In an electronic amplifier, the equivalent would be the gain between the input and output. For the greenhouse, the gain can be measured as the global average surface upwelling radiation (W/m2) divided by the global input, the average TOA incoming solar radiation (W/m2) after albedo. For the earth this is ~ 390W/m2 upwelling surface radiation, divided by the input of ~ 235 W/m2 after albedo, or about 1.66. That’s one way to measure the gain the surface of the earth is getting from the greenhouse effect.
Note that the surface temperature is exquisitely sensitive to the surface gain of the greenhouse effect. The gain is a measure of the efficiency of the entire greenhouse system. If the greenhouse gain goes down from 1.66 to 1.64, the surface radiation changes by ~ 4 W/m2 … on the order of the size of a doubling of CO2. Note also that the greenhouse gain depends in part on the albedo, since the 235W/m2 in the denominator is after albedo reflections.
Here is the core issue. For the “greenhouse” system to have its full effect, the sunlight absolutely must be absorbed by the surface. Only then does it get the surface temperature gain from the greenhouse, because some of the surface radiated energy is being returned to the surface. But if the solar energy is absorbed in the atmosphere, it doesn’t get that greenhouse gain.
So that is what is happening in Figure 1. The black carbon short-circuits the greenhouse effect, reducing the greenhouse thermal gain, and as a result, the atmosphere warms and the surface cools.
PART II – Almost Black Carbon
R2008 discusses the question of the 0.9 W/m2 of TOA forcing that is the net of the atmosphere warming and surface cooling. What I want to point out is that the 0.9 W/m2 of TOA forcing is not fixed. It depends on the exact qualities of the aerosol involved. Reflective aerosols, for example, cool both the atmosphere and the surface, by reflecting solar radiation back to space. Black carbon, on the other hand warms the atmosphere and cools the surface.
Consider a thought experiment. Suppose that instead of black carbon (BC), the atmosphere contained almost-black carbon (ABC). Almost-black carbon (ABC) is a fanciful substance which is identical to black carbon in every way except ABC reflects a bit more visible light. Perhaps ABC is what is now called “brown carbon”, maybe it’s some other aerosol that is slightly more reflective than black carbon.
As you might imagine, because almost-black carbon reflects some of the light that is absorbed by BC, the atmosphere doesn’t warm as much. The surface cooling is identical, but the almost black carbon reflects some of the energy instead of absorbing it as black carbon would do. As a result, let us say that conditions are such that ABC warms the atmosphere by 1.7 W/m2 and cools the surface by -1.7 W/m2. There is no physical reason that this could not be the case, as aerosols have a wide range of reflectivity.
And of course, at that point we have no change in the TOA radiation, but despite that the surface is cooling.
Which brings me at last to the point of this post. To remind everyone, the canonical equation says that the change in surface air temperature ( ∆T ) in degrees Celsius is some constant “lambda” ( λ ) times the change in TOA forcing ( ∆F ) in watts per square metre (W/m2). Or as an equation, ∆T = λ ∆F, where lambda( λ) is the climate sensitivity.
But in fact, all that has to happen to make that equation fall apart is for something to interfere with the greenhouse gain. If the efficiency of the greenhouse system is reduced in any one of a number of ways, by black carbon in the atmosphere or increase in cloud albedo or any other mechanism, the surface temperature goes down … REGARDLESS OF WHAT HAPPENS WITH TOA FORCING.
This means that the surface temperature is not simply a function of the TOA forcing, and this clearly falsifies the canonical equation.
In fact, I can think of several ways that surface temperature can be decoupled from forcing, and I’m sure there are more.
The first one is what we’ve just been discussing. If anything changes the greenhouse thermal gain up or down, the TOA radiation can stay unchanged while the surface radiation (and thus surface temperature) goes either up or down.
The second is that clouds can decrease the amount of incoming energy. It only takes a trivial change in the clouds to completely counterbalance a doubling of CO2. This is a major function of the tropical clouds, which counteract increasing forcing by forming both earlier and thicker.
The third is that the system can change the partitioning between the throughput and the turbulence. The throughput is the amount of energy that is simply transported from the equator to the poles and rejected back to space. On the other hand, the turbulence is the energy that ultimately goes into heating the climate system. In accordance with the Constructal Law, the system is constantly evolving to maximize the total of these two.
Fourth, the El Nino/La Nina system regulates the amount of cool ocean water that is brought to the surface, as well as increasing the heat loss, to avoid overheating. (One curious consequence of this is that the surface temperature in the El Nino 3.4 area has not warmed over the entire period of record … but I digress).
Part III – CONCLUSIONS
The conclusion is that the simplistic paradigm of a linear relationship between temperature and forcing can’t survive the observations of Ramanathan regarding black carbon. For the surface temperature to vary without changes in the TOA forcing, all that needs to happen is for the greenhouse thermal gain to change.
w.
APPENDIX- How it works out
For the math involved, let me steal a diagram from my post, “The Steel Greenhouse”
Figure 2. Single-shell (“two-layer”) greenhouse system, including various losses. S is the sun, E is the Earth, and G is the atmospheric greenhouse shell around the Earth. The height of the shell is greatly exaggerated; in reality the shell is so close to the Earth that they have about the same area, and thus the small difference in area can be neglected. Fig. 2(a) shows a perfect greenhouse. W is the total watts/m2 available to the greenhouse system after albedo. Fig. 2(b) is the same as Fig. 2(a) plus radiation losses Lr which pass through the atmosphere, and albedo losses ( L_albedo ), shown as W0-W. Fig. 2(c) is the same as Fig. 2(b), plus the effect of absorption losses La. Fig. 2(d) is the same as Fig. 2(c), plus the effect of thermal losses Lt. These thermal losses can be further subdivided into sensible ( L_sensible ) and latent heat ( L_latent ) losses (not shown).
We are interested in panel (d) at the lower right of Figure 2. It shows the energy balances.
As defined above, the thermal gain ( G ) of a greenhouse is the surface temperature (expressed as the equivalent blackbody radiation) divided by the incoming solar radiation after albedo. In terms of the various losses shown in Figure 2, this means that the greenhouse thermal gain G is therefore:
where
The important thing to note here is that if any of these losses change, the greenhouse gain changes. In turn, the surface temperature changes … and the TOA balance doesn’t have to change for that to happen.
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“there is about a 30% chance that their “TOA” forcing, which is atmosphere plus surface, is actually less than zero …”
That’s true just from mathematical point of view assuming surface and atmospheric forcing are independent variables which they aren’t. Under assumption that studied particles are darker than the surface (i.e. convert incoming radiation to heat more efficiently), total TOA can never be less than zero.
“As you might imagine, because almost-black carbon reflects some of the light that is absorbed by BC, the atmosphere doesn’t warm as much. The surface cooling is identical,”
Wrong. Half of the reflected light reaches the surface, so surface cooling decreases as well.
“This means that the surface temperature is not simply a function of the TOA forcing, and this clearly falsifies the canonical equation.”
The canonical equation is only concerned about greenhouse gases and assumes not effects, but changes to other factors are negligible. To falsify the canonical equation, you need to show that changes (natural + anthropogenic) to other factors are significant enough.
“the canonical equation says that the change in surface air temperature ( ∆T ) in degrees Celsius is some constant “lambda” ( λ ) times the change in TOA forcing ( ∆F ) in watts per square metre (W/m2). Or as an equation, ∆T = λ ∆F, where lambda( λ) is the climate sensitivity.” [emphasis added]
My understanding of the claim is that an “enhanced” GHE (increased forcing but not @TOA) slows radiant heat loss from TOA, not an increase in “TOA forcing” (down-welling?). I’m not sure if anyone would agree with the “canonical” nature of the equation with a TOA limited forcing. In other words, I think you falsified an equation that’s not canonical with the forcing being limited to TOA.
I agree that [∆T = λ ∆F] is way too simple, at the very least λ is not a constant that we just haven’t been able to nail down yet. No, there are far too many “thermostats” in play over far too many different time intervals for such a simple linear response; rotation, seasons, cloud formation, PDO, sphere (cold poles-hot equator), Milankovitch cycles, etc. that can easily dump “excess” heat (lol) to space.
Willis-
Thanks for another great post. As I have said before, you always make me think.
.It bothers me that the CAGW modelers always talk about black carbon. Yet don’t define it. There are lots of particles and aerosols in the air. When light strikes a particle it is either absorbed or scattered. The amount absorbed and scattered is expressed by the complex index of refraction. Different particles have very different refractive indexes. Different forms of carbon even have different refractive indexes. The value of the complex index of refraction should be the begining of the model input. Yet you never see that value mentioned. I ran across a survey paper that covers a great deal of the physics of particles as it relates to climate models. If you haven’t already read it, it might be worth a look:
http://www.peer.caltech.edu/Particulate/Aerosol/mines/Light%20Absorption%20by%20Carbonaceous%20Particles-Review_Bergstrom_AST_2006_39_1.pdf
Incidentally, the paper gives the following definition of climate forcing.
“Climate forcing is most often defined as the change in net
radiative flux at the tropopause attributable to a specific component.
A positive forcing is an increase in flux, tending toward
warming of the Earth-atmosphere system. Forcing is so called
because it is an input to the system determined by factors outside
it. Figure 1 shows how the change in radiative transfer is
determined from atmospheric concentration of light-absorbing
particles. Most climate modelers first assume physical properties
(size, shape and state of mixing, categorized as morphology)
and a refractive index, obtain scattering and absorption cross sections,
and apply those properties to modeled concentrations. A
few models of global climate have examined effects of differing
morphology (Haywood and Shine 1998; Chung and Seinfeld
2002) by comparing climate forcing calculated with different
assumptions”.
Willis-
One other comment. While I dislike pedantry, I do think you need to change the sentence above your equation defining “G” from:
….the thermal gain ( G ) of a greenhouse is the surface temperature divided by the incoming solar after albedo.
to:
….the thermal gain ( G ) of a greenhouse is the surface radiative flux divided by the incoming solar radiative flux after albedo.
Since all the terms in the equation are in watts per square meter.
[Thanks, I’ve clarified the main text. -w.]
I can only imagine the narrative of a future documentary.
Earth.. The only planet in our universe that is warmed by coolant. Controlled by forcings of an unspecific nature, warmed by media cycles that seem to follow seasonal variations that are governed by solar influences, solar influences that are out right dismissed.
EARTH.. Ship o’ fools. Exclusive to channel WUWT.
E.M.Smith says:
March 27, 2012 at 7:16 pm
In that case let me assist you. Here’s a whole page defining the term, from the IPCC report …
Read the whole page, it lays out the way it is used in the field of climate science. I know you don’t like “forcing”. I don’t either. But that’s what’s used in climate science … so you might as well get used to it.
w.
Sparks says:
March 27, 2012 at 8:56 pm
See the definition above. Neither you nor E.M. Smith have done your homework.
w.
Brown carbon, hmmm …
Andreae, M. O. and Gelencsér, A.: Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols, Atmos. Chem. Phys., 6, 3131-3148, doi:10.5194/acp-6-3131-2006, 2006.
http://www.atmos-chem-phys.net/6/3131/2006/acp-6-3131-2006.html
(open access)
Willis Eschenbach says:
March 27, 2012 at 11:10 pm
“you nor E.M. Smith have done your homework.”
Willis, Cut the crap mate! (is that too strong?) When did your world revolve around the IPCC or what it has to say. I haven’t been giving any home work lately by the IPCC.
I do try, I think you have a good understanding of these issues, and you are an excellent educator, and that is why I like to pick you brain every so often. We can only kick a dead horse so many times!
Sparks says:
March 27, 2012 at 9:29 pm
“Carbon ice”? “Carbon in a gaseous form”? “100watt UV lamp”?? My friend, I fear that makes no sense. I said nothing about any of those.
You misapprehend me and my post entirely. There is nothing in it about “carbon in a gaseous form”. It’s about an aerosol (fine particulate matter suspended in the air) called “black carbon”, which is also known as soot, as I stated in the third sentence.
So I fear I don’t understand what you think I said about “gaseous carbon”, since I said absolutely nothing about it.
You go on to say:
Dang, spaceman, you are a long ways from Earth. Again, you seem to be talking about another post than the one I wrote, even another planet. Let me strongly suggest that if you disagree with something I’ve said, QUOTE MY WORDS EXACTLY. I said nothing about something being “warmed by a coolant”. I said nothing about media cycles. Where does this stuff come from?
Can’t help you with that. I don’t know why you are on a ship of fools, why you are calling EARTH on your ship’s radio, or why you have opened an exclusive channel to WUWT.
But now that your exclusive channel to WUWT is open, my suggestion would be that you use it to actually discuss the issues and ideas. If you disagree with me, then quote my words so we both know what you are talking about. That way we avoid misunderstandings.
Because I can defend my own words, and I’m happy to do that, to explain and defend what I’ve said.
What I can’t and won’t do is to defend your misunderstandings and fantasies about what I’ve said.
Thanks,
w.
Kasuha says:
March 27, 2012 at 9:30 pm
It is generally accepted that reflective aerosols cool both the surface and the atmosphere.
And, as R2008 points out, black aerosols cool the surface but warm the atmosphere.
On my planet, that shows that surface temperature and atmospheric temperatures are independent variables. Don’t know how it works on yours.
w.
@WIllis:
No, I don’t need to ‘get used to it’. Though I do appreciate the pointer to where they have made up some jargon. Jargon, however, is not physics. It still needs to be converted back to something that is a physics term set in order to have any hope of solving a physics problem.
I might as well define a Royal Phisbin as when the earth cools by a net negative energy flux from human mass to planet mass ratio and then declare the globe cooling as human mass is increasing. We simply don’t get to “make it up as we go along”.
So again, thanks for the pointer to where the made up term first is defined. Now we’re up to what?, three variations on what it might have meant so far? W/m^2 then (Average standard W/m^2) and now it’s a whole formula:
‘the change in net (down minus up) irradiance (solar plus longwave; in W m–2) at the tropopause after allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values’
(But without any statement about averaged over some long time period…)
So, please refrain from accusing of “failure to do homework” when you have given me 3 different statements in the same post…
I’ll now go back and TRY to re-read what you wrote sticking in the paragraph version of “forcing” to see if there is any added ‘reality’ injected by it; but on first look it’s not encouraging.
We’ve got a ‘down minus up’ that needs clarification, then we have “longwave” that’s a bit vague, now we also have a ‘tropopause’ (that tends to move and wander – and is not a fixed layer anyway as it has eddies, tears, and convective plumes that put dents in it; oh, and altitude varies with latitude) effect to try to figure out what THAT is in SI units and after that we get to ponder “readjust to radiative equilibrium”… and then a “hand wave” to “Surface and tropospheric temperatures and state held fixed” when no such fixed state exists…
So again I’m left at exactly the same point: “Forcing” is an aspirational statement and NOT physics. Nice for making hypothetical “toy worlds”, but disconnected from reality. Fine for what is expected from “climate science”, but I think your work is typically far beyond them and has a good handle on physics and reality anchors. Thus my frustration when you let their “fuzzy terms” crawl into your normally clear and clean thinking.
In essence, the latest “definition” of ‘forcing’ given here is a statement of a toy world state and is not physics. A term for how parameters are to be set in a computer model, but not a statement about how the world works. Not anchored in SI units nor in physics, but anchored in a toy world where one can have “Surface and tropospheric temperatures and state held fixed” in an algorithm; unlike in reality.
Again, I’m not tossing rocks at you. I’m just trying to map the posting to physics as I learned in college and translate any “local jargon” to what it means in that system, if anything. Finding that it’s “Unphysical” is just fine with me. It means I can not bother expecting any actual ties to reality. Ive done programming and I can play with ‘toy worlds’, I just prefer not to confuse them with anything real.
Willis Eschenbach says:
March 27, 2012 at 11:40 pm
I enjoyed every moment! do you feel good now? bringing up irrelevant argument’s, soot, fine particles, who cares? you’re not in any danger, I know these things! ha! Classic Willis!! spaceman? funny!
Sparks says:
March 27, 2012 at 11:30 pm
Thanks, Sparks. My point was that “forcing” and “radiative forcing” are not some undefined term as you and E.M. Smith foolishly claimed. When I said you hadn’t “done your homework”, I meant that a simple google search would have brought up lots of definitions, someone gave another one above.
I chose the definition from the IPCC glossary because for all the faults of their reports, their glossary reflects how the words are used in the field. But I could have chosen other definitions … as you could have done as well, if you’d done your homework before claiming that there was no definition for the term.
Regards,
w.
PS—You ask, is “Cut the crap, mate!” too strong?
Well, no, if you are right it’s likely not too strong.
When in fact you haven’t done your homework, however, it’s way, way too strong …
Very thought-provoking. And very well presented too. I have also just read the two sister articles you linked to (it’s not about feedbacks; Thermostat Hypothesis). A lot to take in but just quickly (and at the risk of appearing foolish) I wonder if you have considered whether some of the concepts/ ideas central to complex systems analysis might be prove useful in helping you develop your hypotheses further?
For example, your descriptions of clouds/storm clouds/storm systems (heat engines) could describe the interacting agents that characterise complex systems – with information flows between agents consisting of eg., heat energy flux, wind/ air/ water vapour movements; threshold phenomena, self-organisation and spontaneous assemblage are also important feature sof many types of complex system (biological as well as non-biological) and emergent behaviour(s) eg. that generate stability, adaptation, and evolutionary change at a variety of spatial-temporal scales… just a thought.
E.M.Smith says:
March 27, 2012 at 11:51 pm
Yes, you do need to get used to it, because the term is widely used in the field, and the field is not going to change to fit either your preferences or my preferences. You want fun? You think those definitions are inadequate? Take a look at the subdivisions of forcing. Here’s enough to give you a flavor …
blah, blah, blah …
They go on to define other forcings, Fg and Fs, read the paper for the whole gory account.
I don’t like it, you don’t like it. But the terms are an unalterable part of the jargon of the science. Can we move on?
w.
Can someone who has an active interest in science be accused of not doing their homework?
Willis, I never said it was “Undefined”, I said it was a ‘fuzzy term’, and it is. You have given 3 variations on what it meant. And I did do a web search. Found two definitions, neither of which was the IPCC report.
And no, I don’t ever need to get used to it. I “keep a tidy mind” and physics is in one box, ‘fuzzy terms’ in another. I will never allow an untidy idea to assert dominance in tidy areas, like physics.
As I noted above, I’m quite comfortable using it in the “term of art, unphysical, tied to toy world modeling” sense (now that we have that IPCC description). But it will never be allowed into the “physics” or “reality” boxes based on the clear statements of unreal steady states in the definition.
It will, though, always raise a “unreality” flag (in my internal narrative while reading) for any work where it appears as it is based, by definition, on non-real conditions, as you quoted above. For that I thank you.
Per it being embedded in the ‘science’ so must be adopted and internalized: Must we then adopt uncritically and unquestioned such things as aether and phlogiston? They, too, were created terms of art accepted in their day… That is why I ‘keep a tidy mind’ and do not let just any old term crawl in and take over in the tidy parts.
Per “can we move on”: Certainly. I now have what I originally requested, a definition of what this ‘fuzzy term’ is (presuming you are using the IPCC version and not the ‘average W/m^2’ one) and I’m now trying to work out what is the closest thing to reality that might mean as I re-read your work in that context. ( I was happier with W/m^2, BTW, it’s a direct translation without unphysical steady states…)
In general, I “think you have it right”; but I think it would be more authoritatively shown with an exposition using energy flux and not “forcing” with it’s explicit non-physical anchors. Sticking in “W/m^2 in a very short time period as an approximation of a steady state” I think gives a conclusion that is the same as what you got, and is, I think, correct.
Basically, black soot in the air intercepts energy flux and warms the air, prevents it from reaching the ground, which cools. Then looking at it as grids gives a very similar result for all non-polar cells. ( I’d not gotten to the point of thinking about what happens at polar areas with sideways lighting nor ‘the dark side’ yet, then that whole IPCC non-physical toy world definition intruded with yet another iteration…)
So, “moving on”, for me is to use the “W/m^2 very short time slice” to verify a physics based view; then try figuring out what the ‘toy world’ view would be (and is there anything to reconcile between them). The first on the “tidy” side, the second on the “IPCC” side of mind…
Or, short form: From the definition in the IPCC report I know that they aren’t talking about physics, so I can “move on” from even trying to make anything physical out of it. It is a ‘toy world of unreality’ and I can “move on” to just expecting it to be a made up world model…
Sparks says:
March 28, 2012 at 12:17 am
Depends on whether they’ve done their homework, doesn’t it?
w.
The discussion here between Willis Eschenbach and E.M.Smith proves the worth of WUWT.
I suspect many readers have learnt from this discourse.
Willis Eschenbach says:
March 28, 2012 at 1:17 am
Sparks: Can someone who has an active interest in science be accused of not doing their homework?
Willis: “Depends on whether they’ve done their homework, doesn’t it?”
No. the statement does not depend on if home work has been done or not. it implies that it has been done. Doesn’t it?
Spaceman!
http://www.youtube.com/embed/t_9MI2ymN6s
Spaceman!
http://youtu.be/t_9MI2ymN6s
Philip Bradley says:
March 27, 2012 at 5:14 pm
Most studies show surface cooling and upper troposphere warming during the dry season.
Isn’t that due to less water vapour in the atmosphere?
If it is assumed the average cloud temperature is -19 deg C, radiation from a 15 deg C Earth to clouds is only 155 W/m2 for the 70% of Earth with cloud cover, rather than 390 W/m2 surface radiation as claimed. How does this effect the model ?