Visualizing the "Greenhouse Effect" – Light and Heat

Let’s add two more objections to this partial visualization of the Earth System.
1. Where are the storages? Oceans store and release huge amounts of energy. Elaborate your views of the energy/radiation balance.
2. Energy is not just radiation. Earth System is more complex than that. For example, absorbed radiation energy may result in increased cloudiness that has impact on who much radiation reaches the earth. Ignoring major part of the system does not help in believing your conclusions.

This posting is designed to get back to basics and perhaps transform our heated arguments into more enlightened understanding :^)
A little humour goes a long way… Nice, Ira!

3. Show the images to people who Believe and ask them if they still think that CO2 is anything other than a trace gas and ask them if the eensy teensy baby image; 20 pixels (the increase in CO2) looks sufficient to destabilize the other 999,980 parts of the atmosphere!
Yes! and then replace “CO2” with Cyanide and “atmosphere” with your body. If they don’t believe you, just ingest 2mg of cyanide for each kilogram of your body weight (1:500,000) and show those iteyucktuals what for!

The basis for the adjustments to the total absorption due to geometric and reflectivity are based on???

Show the images to people who Believe and ask them if they still think that CO2 is anything other than a trace gas
Remove that “trace” gas and all photosynthetic life of earth dies. And us with it.
Small concentrations can have powerful effects.

Ira,
Thanks for your visualization.
I’d like to comment on your sentence and adress some of the comments here:
“The only rational explanation is the back-radiation from the Atmosphere to the Surface.”
To start, here is my view that I already posted on Climate etc awhile ago..
As I understand it: “backradiation” is the downwelling infrared radiation integrated over all directions that go into the surface.
I am an experimentalist. For me a physical cause is something that I can switch on and off, at least in a thought experiment, and get an intended effect.
If I switch off the sun in a thought experiment, I get cooling of the atmosphere and the surface. If I switch on the sun again, I get warming of the atmosphere and the surface.
If I switch off ”back radiation” in a thought experiment on the night side I get a higher cooling rate.
If I switch on “backradiation” on the night side I get a lower cooling rate.
If I switch on “backradiation” on the day side I get a higher heating rate. Combining my thought experiments I deduct that if I switch on “back radiation” on the day side I get a higher heating rate due to a lower cooling rate because of the “back radiation”
Moreover, I can deduct that with “back radiation” the earth system gets or stays warmer than a reference system without “back radiation”, because of a lower cooling rate.
One might also say “back radiation” leads to a warmer surface compared with a reference system.
However, I do consider sentences as incorrect with respect to physics that state only: “back radiation” is warming the surface.
Of course in any private conversation we state things like: my new coat is warming me nicely. But in a scientific discussion, we need to employ the correct wording, especially in lectures or papers.
For my opinion sentences like: “back radiation” is warming the surface
cause therefore a lot of misunderstanding in the blogosphere. The Gerlich and Tscheuschner discussion is based on it.
Thanks again for your article.
Best regards
Günter

In re Objection #2:
Gas molecules follow ballistic trajectories between collisions…
… unless all the work on Gravity since Galileo is wrong, and doesn’t apply at the molecular level, of course.

I’d like to comment the “However, it is clear that my result, based on matching 240 Watts/m^2, is within a reasonable range of the true mean temperature of the Earth System as viewed from Space.”
Actually for an inhomogeneous body, and even more if it is not a perfect black body, there is nothing like “the true mean temperature”. You can define different averages, but not a single one; the important thing (never clearly stated by climate scientists, although they probably know it very well), is that the average surface temperature (the integral of TdS divded by the surface), is different from the effective temperature Teff which is such that Prad = S.sigma.Teff^4 , where sigma is the Stefan constant. And these temperatures would also be different from a “best fit Black Body temperature”.
The important thing is that you can easily make one of the temperature vary , holding another one constant ! for instance, the average temperature can vary without varying the effective temperature, that is with the same energy budget – and conversely. This can be demonstrated very simply by noticing that the local temperature can be written as +∆T where is the average surface temperature and ∆T a surface (not temporal) “anomaly”. But the only condition is that = 0. Any repartition with a vanishing surface average gives the same average temperature, but NOT the same effective temperature, since on average the won’t vanish.
This lets a lot of room for spontaneous variation even with no change of forcings. This is carefully hidden under the name of “unforced variability”. After all during El Niño/La Niña cycles, the average temperature changes by several tenths of °C (= several decades of observed trend ! ) without any significant change in the energy budget.
The gospel of climate science is that the unforced variability is restricted to 30 years, which would mean that its power spectrum is cut-off for longer variations. But it can be easily seen that this cannot be true. Natural variability is necessary to explain that long term, secular variations, at century and millenium scales. If it were restricted to 30 years, for instance, the paleoclimate data should show that the average temperature should follow very closely the forcing (Milankovitch) curve, which is obviously not the case. And there are obvious physical reason why the Earth climate could oscillate naturally on millenium scale – for instance that’s the characteristic timescale of thermo-haline circulation and it can be expected to give cycles at this frequency. This is much overlooked by climate scientists, in my sense.

Ira
Congratulations, you have provided a good, visual explanation of the basic energy inputs and outputs for the earth. The devil is, of course, as I am sure you would agree, in the detail.
When calculating surface temperatures, variations in the assumed constants in the equations need to be considered. To me the most obvious ‘variable’ constant is that assumed for the earth’s albedo. Spatial and temporal variations due, amongst other things, to the ability of H2O to exist as all three of its phases within the surface and atmospheric regions of the earth, coupled with the large amounts of energy emitted or absorbed at the transition temperatures result in variations in cloud and ice cover, affecting both incoming and outgoing radiation and provide major feedbacks.
When these are coupled with the vast energy storage capabilities of the oceans and more subtle long-term variations of energy input imposed on the earth and solar system from ‘external’ sources known and unknown, the prediction of the earth’s surface temperature variation over an extended period is not within our present capabilities.
In my view the attempts by the powers that be to convince us that the science is settled are the only significant source of ‘hot air’ in the debate!

grrr I should’nt use > for average. The correct thing is that
T = Taverage + ∆T
with the condition ∆Taverage =0

Alcheson;
Since the earth’s core is molten (very hot), there must also be convection of heat from the core to the surface. How much of the extra 33K heat can be attributed to earth’s own heat source? Is it none?… a little?…. or perhaps a significant amount of the 33K?>>>
When I first became interested in climate science that was one of my questions. After much reading and research and my own back of the envelope calculations, the answer came out “insignificant”. Same for radioactive decay of elements in the earth, and I even calculated the energy released by burning of fossil fuels… in the end, all insignificant. Solar rules.

“The only rational explanation is the back-radiation from the Atmosphere to the Surface.”
Has anyone actually calculated how much energy can be absorbed by the GHG molecules in the air? Radiation is not the only heat transfer mechanism.
I have difficulty rationalizing how 2% of the molecules in the air (H2O and CO2) can heat themselves, the other 98% of the air molecules, and the earth surface, by 33K only through back radiation of IR. The GHGs absorb and emit IR but the other air molecules can’t so the heat transfer has to be through collisions. What is the probability of a non-GHG molecule to collide with an excited GHG molecule compared to the probability of colliding with the earth surface and have direct energy transfer from there? (Equally reasonable, we could have “back-collisions” as well, when an air molecule with higher energy than the earth surface, transfer its excess energy back when colliding). If the energy can be inhibited from instantly going out into space by being absorbed by 2% air molecules then it must also be inhibited by being absorbed by e.g. oceans, and released at a later moment. (Some of the energy is also stored in vegetation through the photosynthesis which uses energy from the sun to convert H2O and CO2 into oxygen and cellulose, but that is a longer time perspective.) As has been pointed out in previous postings, we can’t gain more energy than we receive from the sun, but we can delay its disappearance so the 33K energy that is missing has to originate from the sun anyway. Earth is not at instant equilibrium (never at equilibrium at all), and there are many variables that can affect the energy budget at any instant.

Ira,
Very detailed explanation. Hard to argue with the fact that when one breaks the data down into that much detail, one gets only one possible conclusion. Either that or all the physics we know that engineers use every day to make planes fly, internal combustion engines that work, air conditioners that cool, furnaces that heat, are wrong. Since the planes they design do fly, the engines work as expected, the air conditioners cool exactly as designed and furnaces heat right to specification, either the physics is right or a few billion calculations based on the physics got it right by pure coincidence. I’ll put my money on the physics!
That said, you can break this down to a much simpler calculation. The sun’s radiance doesn’t get absorbed 100% by earth surface. Some of it is absorbed by the atmosphere. Similarly, the earth’s radiance is not released 100% from the earth’s surface, some of it is released by the atmosphere itself. So the earth surface might be 288K, but as seen from space, any given outward bound photon could have come from the earth’s surface or from the atmosphere. Seen from space, earth is not a “surface” but a sort of fuzzy/murky/semi-transparent sphere. Take any “area” that you can “see” from space, and measure the w/m2 being emitted, and you get a total that is mostly originating from the surface, and some that originated from the atmosphere.
If we assume that your 240 w/m2 is correct, we can use Stefan-Boltzman Law to calculate the “effective” black body temperature of the earth, which if you accept “average” as an argument, would occur not at earth surface, but somewhere between earth surface and the top of the atmosphere.
SB Law being P=5.67*10^-8*T^4
If we use P of 240 watts/m2 we get T of 255.07 degrees K or -17.93 degrees C.
The same logic still applies. Since we can measure what’s going into the system at TOA (top of atmosphere) as well as what is coming out, and the various satellite measurements and experiments like ERBE and others all arrive at a MEASURED value of arounf 240 w/m2, then there is only one possible conclusion. Earth surface is 288K or +15C on average because the atmosphere retains heat that keeps the surface warmer than it otherwise would be. Call it “less cooling” or “back radiation” or “invisible pajamas” but the measurements and the math arrive at the same conclusion. 240 watts/m2 going in =240 watts/m2 going out = -18C. Since the earth surface is +15C, it can only be 33 degrees warmer because the invisible pajamas are making it warmer.

Thanks David. Seems the radioactive decay of elements is estimated to be ~30TW (thought to be ~80% of the earth’s internal heating based on Wikipedia) which would result in about 0.1K of the 33K difference. Wonder how well that value is actually known? Off hand, 30TW doesn’t seem like a lot to keep the earth’s core molten. I might have to spend some more time investigating how that 30TW was derived, and see if it makes sense given the thermal conductivity and temperature gradient of the earth to convince myself as well that it is totally insignificant.

Ira
You should read the article below.
It will answer all of your misconceptions about the “greenhouse theory” which in fact is pure fiction.
1. It is true that the radiative equilibrium temperature of the Earth is -18C.
2. This figure is confirmed by Satellite measurement from space.
3. It is NOT true that all the radiation emitted from the Earth surface.
4. The emission is mostly from the cloud level.
5. If we pick say around 5km as the average emission height to space we will be near enough.
6. Now use thermodynamics expressed in the form of the lapse rate.
7. An average moist lapse rate is -6.6K/km.
8. The lapse rate has nothing to do with back radiation as even scienceofdoom admits.
9. Work back down from -18C at 5km to the Earth surface and we get 5×6.6 = 33K.
So now you have an Earth surface temperature of 15C without any “greenhouse effect”.
http://www.ilovemycarbondioxide.com/pdf/Understanding_the_Atmosphere_Effect.pdf

I’d like to run a little thought experiment here, and ask a question. I’m not pushing an agenda. It’s a very long time since I had the maths to follow the physics above, and I’m too idle to re-learn.
Given a warm radiating surface, and cooler atmosphere of, say, 1 molecule. The surface radiates 10 units of energy out. Nine escape, one unit is trapped by the molecule, and re-radiated back to the surface. Net result is a loss of nine radiation units from the surface. The 2nd law of thermodynamics is satisfied: the cool body is not heating the warm body, merely slowing the cooling rate. Effectively “insulating” the surface (but not in the sense of a “blanket” preventing convection).
Isn’t this the effect of “back-radiation”?

Gotcha Henry!
He thinks CO2 is like a toxin in the atmosphere!
An amazing toxin which is NOT TOXIC at 380ppm but suddenly BECOMES TOXIC at 400ppm. There in a single post is the fuzzy thinking of the Warmists! Fantastic.
Textbook example of ‘Carbonaphobia’!

JT says:
I am well aware that spontaneous emission is equally likely to be in any direction so that approximately 1/2 will head downward to the surface. However, there is another kind of emission – stimulated emission – and it is massively biased in the same direction of travel as the direction of travel of the stimulating photon.
This is I believe wrong in that you are assigning some kind of kinetic impact of the photon even though you call it stimulated emission. The photon has no mass, so when it is absorbed it is the electromagnetic properties of the photon that is acting on the molecular structure. In an instant the electromagnetic fields of its components are both attracted and repelled depending on the phase polarity of the photon at the time of absorption.
I find wave theory a better example of the action. At rest the molecule is in balance with its competing fields. The magnetic wave is an oscillation of both positive and negative fields. Dependant on it’s phase, the approaching wave will attract all components of the molecule that are the opposite polarity and repel all those the are the same polarity. As the wave progresses, the polarity is reversed and the components that were repelled are now attracted and those that were attracted are now repelled.
The energy of the wave has now been absorbed and for a brief time the molecule has kinetic energy as, notionally the competing fields struggle to reach equilibrium. In doing so the molecules components that are now vibrating disturb the electromagnetic balance of all the surrounding molecules electromagnetic fields which due to their state of equilibrium with the wider body of gas offer resistance but must acquiescent to the force of the field by propagating the energy though out medium.
The above thought bubble only applies to an ideal gas.

You state that the back radiation has been measured. Well it might, or at least some long wave IR that is more probably short wave IR that has lost energy traveling through the atmosphere. It would be impossible to tell the difference from measurements at the surface. It is also true that if a molecule of any so called ‘greenhouse gas’ adsorbs energy it must, by 2nd law rules, share this energy with the surrounding non ‘greenhouse’ gasses, ie it loses heat through conduction and radiation.
I do not see in your calculations any adiabatic effect which is important. Taking this into account raises the temperature at the surface. Also, when any gas is heated it will convect. Not an easy effect to measure in the laboratory compared to the real atmosphere. Convecting air will cool.
Jupiter, with an atmosphere of mainly hydrogen, has warming at the 1 atmosphere level similar to Earth. So there it must be an adiabatic temperature rise not ‘greenhouse effect’. Solar input out there is much lower than Earth’s.
True, glass does not transmit IR energy but a greenhouse, transmits visible light and so doing allows energy losses inside, warming the interior by visible light. These losses mean that the lower wave light converts to IR which cannot be transmitted out through the glass. This, together with lack of mixing with cooler external air raises the internal temperature. At night the temperature falls rapidly. 2nd law dictates that the higher the temperature difference of two bodies the greater the heat flow between the two bodies. Entropy must increase.
Taking into account the adiabatic effect, which is real and measurable, there is no need for the GHG effect.
The greenhouse effect also has one fatal flaw. The warming in the mid troposphere in the tropics shown by all models has yet to be found in real observable data. I do not care what your calculations show (in reality another model), if this warm area shown by models is not there then the theory falls flat on its face!

Bob_FJ says:
The solar constant for Earth is commonly given at 1366 W/m^2, and to make a simple average of what is absorbed over the surface and atmosphere, and absorption rates etc, (and the outgoing emissions, spread over the entire sphere), when the wattage is proportional to the fourth power of T, introduces a few complications. In short, might I suggest that the effective radiative T of Earth as is popularly touted is uhm questionable.>>>>
One of… OK, my BIGGEST pet peave. There is no such thing as an average temperature or w/m2 that is all that meaningfull. The rough estimate commonly used in climate circles is 1366 x .5 (for day/night) = 683. 683 x .5 (cuz its a sphere) = 360. 360 x .7 (for albedo) = 250, pretty close to Ira’s 240.
But that of course would be around 500 w/m2 at high noon at the equator, and pretty much 0 for six months at a time at the poles. So despite being relatively cold, the poles actually beam way more energy into space than they recieve from the sun, and the equator, despite getting very high insolation year round (in daytime at least) is a net absorber (the excess being moved away by wind and water currents).
So trying to come up with an average insolation value and an average temperature value is meaningful in terms of the total of each. But since insolation varies with w/m2 and w/m2 varies with T^4… trying to track “warming” by following “temperature” is silly. 1 watt of extra insolation results in a much larger temperature anomaly at the south pole than it does at the equator. So when the IPCC says that the “average” temperature of the earth has increased about 1 degree “on average” since 1880, that is highly misleading.
But if they said about 0.3 degrees at the equator and about 1.5 degrees at the poles, it would sound a lot less alarming. And before anyone starts screaming about the ice caps melting, let’s keep in mind that T^4 applies by latitude as well as season. So to get an even more reasonable expression of that “one degree average” they would need to say something like:
Equator +0.3 degrees all year round.
Poles +0.5 degrees in summer
Poles +2 degrees in winter
In other words, that scary “one degree” is mostly confined to the dead of winter in high latitudes. Sorry “the ice caps are melting we’re all going to drown” crowd, but if the poles go from -40 in the dead of winter to -38, the extra melting would be…. between almost zero and zero. And neither the polar bears nor the seals will notice. Or mind.

“I modified the Carleton spreadsheet to compute the mean Solar radiation per square meter absorbed by the Earth System, which turns out to be 240 Watts/m^2. I then used the spreadsheet to determine the effective mean temperature of the Earth System that would emit an equal amount of energy to Space, and that turned out to be 255 Kelvins (-18ºC which is 1ºF).
Since the mean temperature at the surface of the Earth is 288 Kelvins (+15ºC which is 59ºF), that leaves 33 Kelvins (33ºC which is 58ºF) to be accounted for. Guess how we acount for it?”
We can account for the 33C difference without any need for an imaginary greenhouse effect. I urge everyone at WUWT to read this brilliant paper by physicist Joe Postma ;
http://www.globalwarmingskeptics.info/forums/attachment.php?aid=327
In this paper, Joe accounts for the 33C. The truth is that the radiative temperature of the Earth is measured from space IS -18C. And it is true that the average air temperature near the surface of the earth is 15C. However, if one includes the whole of the atmosphere right up to the edge of space and the surface of the earth in calculating the average radiative temperature of the Earths surface [i]and[/i] atmosphere, then we get to the -18C figure.
There is no discrepancy, there is no need for an imaginary “greenhouse effect”.
Surely the Phlogiston of our times!

Alcheson;
Off hand, 30TW doesn’t seem like a lot to keep the earth’s core molten.>>>
You’re thinking about it wrong way round. The 30 TW (actually I think it is 44 TW but no matter) is what ESCAPES from the molten core to the surface. OK correction, the outer core is molten, the inner core is actually solid. Fact is that dirt and rocks are pretty good insulators. In high latitudes where winter temps might be as low as -40, houses have to be constructed on a foundation that goes below the “frost line”. That line is a few feet below the surface and in even the harshest of winters, the dirt only reaches the freezing temperature by no more than an inch or so deeper than average. Get about 10 feet down and the temperature varies by almost nothing all year round. So figure that molten outer core is insulated by kilometers of dirt and rock…the heat gets out…but slowly.
There’s a decent summary at wikipedia (not the best source for climate info but good enough in this case) http://en.wikipedia.org/wiki/Earth's_energy_budget
Geothermal about 0.08 w/m2
Tidal about 0.006 w/m2
Fossil Fuel consumption about 0.025 w/m2.
Compared to 250 w/m2 from solar… pretty minor.

Notice that the Earth System mean temperature I had to use to provide 240 Watts/m^2 of radiation to Space to balance the input absorbed from by the Earth System from the Sun was 255 K. However, the actual mean temperature at the Surface is closer to 288 K. How to explain the extra 33 K (33ºC or 58ºF)? The only rational explanation is the back-radiation from the Atmosphere to the Surface.
255K is the mean earth radiative temperature at around 4,000 metres altitude and above. Escaping IR radiation is from a volume of the atmosphere, not a flat surface.
The mean surface temperature of 288K is simply the compression factor of gravity on the air. Air at the surface has the highest density and returns highest temperature. Think deserts, polar regions, equitorial regions. All very different suface temperatures but always the same adiabatic lapse rate, water vapour content allowing.

There is a bathtub which can hold energy. (the earth’s atmosphere/surface/oceans)
There is a energy tap flowing into it. (the sun)
There is a hole in the tub where energy flows out. (radiative emission into space)
Inflow = outflow, energy in = energy out.
The quantity of energy the black-box “bathtub” is able to hold (wants to hold) can go up and down and is indicated by the temperature. When the variables which alter the level stored in the tub are changed (knobs turned) there will be an imbalance between inflow and outflow until the new equalibrium is reached – a equilibrium at which a different level of energy is stored in the tub. We expect a change in the total level of energy stored to affect the temperature at the bottom of the tub.
I expect the IR interference to be one of those variables but I’m sure there are many others. The claim that 30 degrees celsius at the surface is all due to the greenhouse effect is rubbish.
3 scenarious.
A. Black body earth (-30 % albido).
B. Earth with atmosphere and no IR interference.
C. Earth with atmosphere and IR interference.
A is cooler than B is cooler than C.
C – B = greenhouse warming.

We can account for the 33C difference without any need for an imaginary greenhouse effect. I urge everyone at WUWT to read this brilliant paper by physicist Joe Postma ;
http://www.globalwarmingskeptics.info/forums/attachment.php?aid=327”
Agree it was a brilliant paper. But this Postma paper was posted on Ira’s previous thread and Ira and others criticised the paper or would not read it all.
http://wattsupwiththat.com/2011/03/29/visualizing-the-greenhouse-effect-molecules-and-photons/
Ira Glickstein, PhD says March 30, 2011 at 2:02 pm
This post by Ira has not really moving forward at all with Ira still posting this for example
“How to explain the extra 33 K (33ºC or 58ºF)? The only rational explanation is the back-radiation from the Atmosphere to the Surface.”
This is just total nonsense. (The only rational explanation). It is one explanation and not a very good one. Unfortunately Ira is just ignoring comments on previous thread so this series is not moving forward. He could summarise the main areas of contention without giving a viewpoint rather than posting again his beliefs that he knows many disagree with

Dishman says:

In re Objection #2:
Gas molecules follow ballistic trajectories between collisions…
… unless all the work on Gravity since Galileo is wrong, and doesn’t apply at the molecular level, of course.

Ballistic trajectories are trajectories under the action of gravity. Note, he didn’t say they travel in straight lines.
However: the approximate speed of molecules in the atmosphere is about 1,700 km/h. The path isn’t very curved, in other words. And the mean free path of a molecule in air is about 65 nanometres. You’d be pretty amazing if you could measure the deviation from a straight line of a path segment with that length and curvature.

“Heat always passes from hot to cold, never the other way round, THERE ARE NO EXCEPTIONS!”
What about the sun corona? It’s a million degree and sun surface is cooler.
Perhaps you referring to solids. Such as warm air can not heat up a warmer surface via radiant energy.
Say, you had an object in space and it’s temperature was 100 K. This is a cold object, -173 C but compared to background temperature of Space 2.7 K it’s fairly warm. And it is certainly radiating energy into space. No part of earth is as cold as 100 K, if colder can not pass to warmer this means that with infrared telescope on Earth you could never detect such a cold object in space. It also means that your telescope mirrors would need to as cold or colder than any cool object you wanted to observe.

Radiant energy accounts for all of the outbound energy at the top of atmosphere, but only a fraction of the energy transfer at the surface. Understanding how the energy moves up through the atmosphere via non-radiative pathways is key in estimating potential GHG effects.
If we use values from Kiehl & Trenberth 1977, they show 60% of the surface energy transfer to the atmosphere is due to Thermals (convection) plus Evapo-transpiration (water evaporation and release as latent heat). Leaving no more than 40% as Radiant Energy transfer, with 24% of that 40% as direct loss to Atmospheric Window. Whatever the GHG affects may be, they are happening in the 16% of the total that is left. (And I read somewhere that Trenberth used 40 W / m-2, knowing that the actual ‘window’ value was more like 66 W/m-2. That would increase the ‘atmospheric window’ from 24% to about 39%, leaving only about 1% of the total for the net of all other radiant emissions).
How can that be, since we know the surface emits a blackbody distribution dependent on the surface temperature? One possible explanation is to look at what the energy ‘pathway’ might be. Sort of by definition, the radiant energy that is NOT in the atmospheric window wavelengths, is susceptible to being absorbed by one of the GHG, mostly CO2 and H2O. So the surface emits radiant energy, and the GHG susceptible wavelengths are absorbed fairly close to the surface. Next, we think that the absorbed photons are more likely to be ‘thermalized’ rather than re-emitted as photons (10,000 : 1 more likely thermalized). Thermalized means the GHG molecule collides with a non-GHG molecule in the air, converting the photon to kinetic energy, which can now be seen on a thermometer. Now all of the non-radiative pathways take over. In essence, the radiant emissions from the surface have ‘speeded up’ the energy transfer to get the energy into the other pathways. Hot air rises, clouds and thunderstorms happen when conditions are right, and generally energy moves up through the atmosphere at something like the wet or dry Lapse rate, as appropriate to conditions. When the energy gets high enough, the radiant pathways again become significant, and eventually take over, sending the energy out to space.
Of course the devil is in the details, but that description seems to fit with what others have said earlier. It is not all about just the radiant component.

Leonard Weinstein
……”The black body would absorb the reflected radiation, and thus the equilibrium temperature would be increased.”……
Yes I agree, he could have been clearer on that point.
This aspect causes a great deal of confusion and some intellectual mischief.
See if you would agree with this formulation.
The reflected radiation is the reflective insulation component.
If increased it will slow down the heat loss from the black body.
If the black body has an unchanged energy input its equilibrium temperature would be increased.
However if the energy input to the black body was cut off the temperature of the black body would drop despite the backradiation.

And i see that others have mentioned Postma. A very good explanation of the lapse rate.

davidmhoffer says:
May 8, 2011 at 3:19 am
“Why doesn’t it keep cooling off? After all, the atmosphere above the arctic is even colder than the arctic itself… Heck, at 25,000 feet its colder than that even at the equator! So… with 0 watts/m2 from the sun, the arctic nonetheless sticks right around -26 degrees. Hmmmmm…..wonder what keeps it from cooling off more….”
David, if the atmosphere above the arctic is colder than the arctic surface, do you want to imply here that this cold atmosphere is nevertheless capable of WARMING the surface? Are you sure you wanted to say that?

This makes sense. Absent CO2 and water vapor, we would freeze. How much warming does each contribute? If CO2 did it all, and mankind producses about 3% of the CO2, then we are responsible for 3% of the 33C warming or about 1C. Thus AGW is real. Except for water vapor which may cause 90% of the 33C, in which case we cause 0.1C warming. Big deal. Given the daily and seasonal variations in temperature, I find it very hard to believe that 0.1C will have any measureable effect. Or be measureable at all.

What is so bothersome about this topic is that people who take it up do nothing but rehearse the Great Assumptions, such as the claim that Earth should be treated as a black body. It’s like listening to discussions among Ptolemy and his colleagues. The solution is always the same: more epicycles and maybe an eccentric or two. Yet in setting forth the Great Assumptions, you mention known facts which contradict them. Earth has albedo. Suppose for a moment that Earth’s albedo became 100%, would that motivate you to change the Great Assumptions. Is an object with 100% albedo properly treated as a black body? Can anyone state a plausible account of Earth’s radiation budget that does not treat Earth as a black body? I don’t believe anyone can and I believe that fact reveals a limitation of imagination, not the firmness of accepted science. I guess we will just have to wait for the science to advance. Anyone know somebody named Kepler?

Ira (con’t):
The first pass you need to make in accounting for this discrepancy is to take albedo into account. The moon’s albedo is constant and accurately measured at some 16% so that amount of insolation doesn’t get absorbed the surface. That will account for the theoretical difference between black-body absorption and reality. The moon would be about 5C warmer if the surface albedo was close to 0%.
The problem doesn’t go away however because the earth has a non-zero albedo too and it isn’t known nearly as well as the moon’s with, depending on who you ask, an average albedo in the range of 32% which is primarily the result of some 70% being shrouded by clouds of some sort at any given instant. The problem here is there is no satisfactory agreement between experiments attempting to measure the earth’s average albedo and estimate range from as little as 30% to as much as 40%. All the experimental attempts to measure the earth’s average albedo do agree on one thing – it isn’t constant and varies by as much 1% year over year.
One percent doesn’t seem like much variation but once again it’s a very large number when compared to anthropogenic warming. A 1% change in the amount of insolation actually reaching the surface and not being reflected directly back out into space is some 2.5 watts per square meter. The IPCC third assessment is “95%” confident that anthropogenic forcing lies in the range of 0.6 to 2.4 w/m2. Yet measured variations in earth’s albedo over just several years has it changing by more watts/m2 than the highest estimate of alleged anthropogenic warming. Worse yet, the actual albedo can’t be pinned down and estimates vary by about 7% which is 7 times greater than anthropogenic forcings.
So how can we possibly start talking about anthropogenic forcings and surface temperature changes wrought by same when we don’t even know to +-5C what the average temperature of the earth should be due to our albedo measurements being so imprecise and having no bloody idea how, when, and why the earth’s average albedo varies.
The earth being a dynamic water world makes all attempts to model it exercises in futility. The models are toys and should be regarded as precisely that – toys with zero credibility.

Bryan stated that using clouds, you get a 33 C temperature difference between clouds and surface “without any greenhouse effect”. I’d say inseead, that a significant fraction of the greeenhouse effect is due to clouds.
Ira Glickstein stated that the warming due to CO2 would only be about 0.2C. Here’s a way to get a rough estimate of the figure:
We get an average of 342 watts/M^2 from the sun.
As others have pointed out, excluding clouds, the average reflectivity of earth’s surface is about 0.124
Earth is not a blackbody, most of the earth is covered by ocean, which has an emissivity between 0.92 and 0.96- I’ll use a 0.94 average. This non- blackbody emissivity means earth actually radiates away less than a blackbody at the same temperature.
A non-greenhouse earth surface would receive an average of
342 *(1-.124reflectivity)/0.94 emissivity would give an average surface flux of
342*0.876/.94 = 318.7 watts. All of the positive and negative feedbacks to the
greenhouse effect give an average temperature of 288K, or effectively 390.7 watts/m^2, for an effective magnification of 1.226
From Trenbeth’s figures,
http://content.imamu.edu.sa/Scholars/it/net/trenbert.pdf
161 watts /m^2 hit the earth’s surface, with back radiation we get a total of 492 watts, not all in sensible heat, for a magnification of
493/161 = 3.06,
Putting the two formulas together, a theoretical additional factor of 2.06 multiplier due to the greenhouse effect becomes an actual multiplier of 0.226, thanks to negative factors like increases in albedo due to clouds, decreases in lapse rate, etc.
A doubling of CO2 would supposedly increase the surface flux by something less than 3.7 watts/m^2, for a total of 496.7 watts, an increase to 335.7 from 332 over the original 161 watt/m^2 hitting the surface.
Multiply that 335.7/332 * 0.226 and we get 1.2285* 318.7 for an effective
wattage increase from 390.7 to 391.52 watts, or a temperature increase to
(391.52/390.7)^0.25 = 288.15K from 288 K – Close to Ira Glickstein’s estimate of 0.2K- a drop in the bucket.

Ira Glickstein, PhD says:
May 8, 2011 at 8:35 am
“The point of my simplified calculation was to show that, absent back radiation from the Atmosphere, there is no good explanation for the approximately 33ºC (58ºF) temperature difference between the “light” input from the Sun and the “heat” output from an Earth that would have to be cooler than it is for the heat balance to work.”
Again: The Earth radiates from the top of the atmosphere and that’s where you find exactly the temperature needed to radiate enough. See also
Harry Dale Huffman : No Greenhouse effect on Venus
http://theendofthemystery.blogspot.com/2010/11/venus-no-greenhouse-effect.html
where Mr. Huffman does the same computations for Venus.

I disagree with answer three. As a fellow systems engineer I appreciate and support your back of the envelope checks. But remember, we also have to explore all feasible answers, and the difference between black body and the actual measured radiation back to space does NOT require a ‘greenhouse’ effect.
It simply requires a long time constant between heating and radiation, which is where heat sinks and non-solar heat sources come into play.
The 33° K difference could simply be a result of a time delay between solar heating and thermal cooling. The heat capacity of the Earth could require the system to bank 33°K of heat before the there is sufficient flow of energy to the upper atmosphere to radiate.
Moreover, the inner core and the active underwater volcanoes could easily be dumping a extra wedge of gravity-friction generated heat (akin to what drives the Io system). What our massive oceans provide is a heat store, not just a heat sink. Gravity-friction (which produce wave action, which transfers kinetic energy into heat) is a source of energy transfer at the surface, as is any flowing water and its passage to the sea.
How much kinetic energy is in a river flowing to the sea? How was that energy stored? It was stored as water vapor evaporating from ground and bodies of water from solar heat, which rise to be COOLED, where the kinetic energy from gravity is then brought back to Earth with the rain. Friction supplies the transfer.
You can identify numerous transitions where heat is captured, converted, released, transferred and held for days, weeks, months and years.
What is wrong with ALL these models is they lack a time constant from which a joule of solar energy can travel through our system – over any one of hundreds of energy transformation paths – before it is made available for radiation. And we never remember to include the yet still unquantified heat source that is at the core of our planet. There is NO dissipation path for that heat except through radiation. It is a massive heat source which could EASILY account for the 33°K difference.
We know so little, yet act as if we have all the answers. The minute that happens we stop being scientists and become zealots.

ferd berple says:
May 8, 2011 at 8:22 am
I don’t want to rain on your parade but the temperature at the top of the atmosphere is in the thousands of degrees. The TOA boundary for energy budget calculations is the top of the thermosphere. So the temperature is indeed much higher at TOA than it is at BOA.
Your argument based on lapse rate is only valid to the top of the middle atmosphere and falls apart in the upper atmosphere where temperature increases with altitude.
It’s very thin atmosphere but it’s still atmosphere and its temperature can be measured. So the temperature at the bottom of the atmosphere is indeed much colder than at the top.

ferd (con’t)
The reason the middle and lower atmosphere get colder with height isn’t because of compression. It’s because in the middle and lower atmosphere the sun doesn’t do any appreciable heating of it.
One must always begin with the big picture and work down to the smaller details not try to add up the details into a big picture.
In the big picture the sun heats the ocean, the ocean heats the atmosphere, and the frigid cold of the cosmic background (3K) cools the atmosphere.
The lower atmosphere is warmer than the middle atmosphere because the lower atmosphere is closer to the source of the ocean that heats it.

Ira said:
“Notice that the Earth System mean temperature I had to use to provide 240 Watts/m^2 of radiation to Space to balance the input absorbed from by the Earth System from the Sun was 255 K. However, the actual mean temperature at the Surface is closer to 288 K. How to explain the extra 33 K (33ºC or 58ºF)? The only rational explanation is the back-radiation from the Atmosphere to the Surface.”
No, by my point o f view there is another explanation. The incoming radiation from the Sun is truly measured from the radiometers because of the distance from the source we get all the parallel energy rays in the SW, while the emission of the Earth in the LW range is scattered in a spheric space around the planet, so the satellites’ radiometers can’t really measure all that energy because those rays are not parallel each other and many of them will never be perpendicular to the radiometer input slit.

Dave Springer:
Please “debunk” the article at the link given by DirkH: http://theendofthemystery.blogspot.com/2010/11/venus-no-greenhouse-effect.html
You folks are, in essence, saying that the lapse rate is CAUSED by the GHE. That is nonsense. The lapse rate is dependent upon only two variables, gravity (g) and the heat capacity of the air (Cp) and can easily be calculated from these two variables. GHE has no “place” in this formula. The lapse rate for ANY atmosphere (even pure nitrogen or oxygen) would be calculated the same way–without “allowance” for any GHE.

No mention is made of ocean and atmospheric heat transport. With one side of the Earth exposed to near absolute zero temperatures and the other exposed to the Sun; any theory has to take into account the movement of vast amounts of heat energy from hot to cold and vice versa. Although the Earth may lose heat at night, there is still substantial heat transfer from the day side to the night side keeping the night side warmer than it would be otherwise. The true “greenhouse effect” is a perfect example. Without convective heat transport a greenhouse becomes much hotter than its unenclosed environment. Simplistic models with lots of fudge factors to make the numbers fit are insufficient to describe the climate.

jae says:

You folks are, in essence, saying that the lapse rate is CAUSED by the GHE. That is nonsense. The lapse rate is dependent upon only two variables, gravity (g) and the heat capacity of the air (Cp) and can easily be calculated from these two variables. GHE has no “place” in this formula. The lapse rate for ANY atmosphere (even pure nitrogen or oxygen) would be calculated the same way–without “allowance” for any GHE.

The lapse rate is not caused by GHE’s per se. Your statement about the lapse rate is more or less correct…except that this sets a maximum lapse rate. That is, it is possible for an atmosphere to have a smaller lapse rate than you get from the stability calculation that you allude to. However, it won’ t have a steeper lapse rate because such an atmosphere becomes unstable to convection, with then brings the lapse rate down to the marginal stability value.
So, the best way to put it is that the lapse rate is caused by the fact that the atmosphere is heated from below in concert with stability arguments based on buoyancy, adiabatic expansion, and the existence of convection.
What the GHEs determine is where in the atmosphere the emitted radiation is able to escape to space. Radiative balance of the earth system then sets the temperature at this level in the atmosphere and the temperature at the surface basically follows from the lapse rate.

Ira,
I have been reading many posts here that discuss the blackbody radiation of the earth. You have claimed that the 33K difference is due to GHG back radiation. I don’t want to argue that with you… but I think it would be worthwhile to be very very clear on exactly what you are claiming.
So… I can boil this down to a simple yes or no question…
Are you claiming that if the atmosphere were replaced with a different set of gasses that do not contain GHG molecules, but still had all the other macro effects such as clouds etc in the exact same amount as our current atmosphere… are you claiming that this atmosphere would NOT cause (directly or indirectly) the surface of the earth to warm at all?
You see… it does seem as if the answer to the above question is yes. It does seem as if you are making that claim. Are you? Or, are we just misunderstanding your argument?
-Anton Eagle

Ira,
I have a second question regarding the two emission diagrams you show.
The upper graph, showing down-looking readings at the top of the atmosphere shows that approximately 1/2 of the 15 um radiation is absorbed. It looks as if it would be about 90 mW/m^2 without absorption, and instead is about 45 mW/m^2 or so with absorption.
Then you show the lower graph showing the up-looking readings at the surface… showing about 90-100 mW/m^2 of radiation (at 15 um) down to the surface from the atmosphere.
So, my question is… if the GH gasses are absorbing about 45 mW/m^2… how are the re-radiating almost 100 mW/m^2 back to the surface?
It doesn’t look like the sun can be the source, since according to these curves the sun doesn’t radiate hardly anything at those wavelengths. So… where is the extra energy coming from?
Thanks,
-Anton Eagle

John of Kent says:
No! The earths surface is already emitting radiation in the Infra Red. It’s atoms and molecules are ALREADY excited sufficiently to be emitting IR.
Yes..The molecules of the earth surface have kinetic energy because they are excited or are being exited with the absorption of radiation.
This excitement distorts the magnetic field of the molecules components in a way that they are not in balance as they would be if the molecule was at rest. This leads the electromagnetic field of the molecule to send out waves of electromagnetic energy into space at decreasing rates if the source of the energy is turned of.
When the source energy is turned off the emitting waves from the molecule don’t cease immediately because the molecules components have mass and it is the movement of these parts that cause the decreasing waves of electromagnetic disturbance as energy is lost.
Similarly when the molecule is hit by a magnetic wave it will not reach its full kinetic and radiative potential until all its parts are moving in such a way as to propagate a field of disturbance equal to the constant of the energy input over time. At this point it is at radiative equilibrium with the incoming energy and no more work can be done.
Let’s say we are on the moon so there is no overlaying gas and pick an arbitrary incoming value of 100Watts/m^2. The mass of the particles at the surface will eventually increase in temperature until the moving parts of the molecules are so excited they cause a electromagnetic disturbance that is equal to the incoming electromagnetic energy from the sun. At this point the waves of energy from the surface propagate outward and are lost to open space. 100Watts/m^2 in, 100Watts/m^2 out.
This however is not the case with our planet. The over laying gas doesn’t impede the inflow of energy to the surface but the principle remains the same as the moons surface in that in its self the surface will move toward radiative equilibrium with the incoming energy.
This time however the outgoing radiation is now blocked by a molecule of gas which of course also has mass and a state of rest.
The propagating electromagnetic wave from the earths surface is now absorbed by the molecule which in turn adopts kinetic and thereby electromagnetic properties as the state of rest is now disrupted and its components vibrate, sending out electromagnetic waves as it struggles to balance its competing internal forces.
Although free floating the rules for the gas molecule are the same as the molecules at the earths surface. It will absorb all the incoming energy from the earths surface until it radiates away the same amount of radiation it is receiving. It will do this in all directions, so as it moves to reach radiative equilibrium with the surface it will radiate half toward the surface and half away. The energy being radiated back to the surface is not kinetic, it is electromagnetic. It would be 50 Watts/m^2 in the first instance of time with the other 50 Watts radiating away. The surface doesn’t know where the 100 Watts or the 50 Watts are coming from it only knows it is receiving 150 Watts in the second instance of time.
Think of this. If we had a closed system where no energy is lost and we were to put 100 watts a second into the system we would have a system with 100 joules after the first second. Now in the next second we only put 50 Watts a second into the system we get 150 joules in the system. The system doesn’t care that the that the last second had a lower value than the first second it only knows that over two seconds it has received 150 Watts of energy.

Ira Glickstein, PhD says:
May 8, 2011 at 10:41 am
“I hasten to add that engineers are not as picky about precision of estimates as scientists and mathematical analysts are about their data. If we get estimates within 15% (33ºC vs 28ºC) that is usually close enough, since other uncertainties are likely to be in the mix. ”
Acceptable margins of error are established in context. Sometimes being within an order of magnitude is good enough and other times the proverbial nine nines isn’t good enough. But I understand your point. It’s illustrated by a trite expression that +-10% is good enough for government work. Left unsaid is that the government screws up a lot because what’s considered “good enough” by them often isn’t.

Martin Mason:
Ira, the Second Law of thermodynamics works at every level and you cannot transfer heat from a colder body to a warmer body. A black body cannot also reabsorb and re-emit lower intensity radiation that it has already emited.
You clearly do not know the basis for the Second Law, which is statistical physics. You seem to believe in some sort of magical version of the Second Law. The actual Second Law is based on the fact that although energy transfers occur in both directions, by simple statistics it becomes essentially astronomically improbable that the net flow of energy, what we call “heat” will be from the hotter body to the colder body for any macroscopic bodies.
In particular, applied to two radiating objects at different temperatures, the Second Law simply states that the amount of radiation from the hotter body that is absorbed by the colder body is always larger than the amount of radiation from the colder body that is absorbed by the hotter body. The laws of radiative transfer automatically satisfy the Second Law when applied correctly and all models of the greenhouse effect, be they toy models or advanced radiative-convective codes, satisfy the Second Law.

Greenhouse heating by back radiation is surely wrong because it says that if you put a frozen steak inside a vacuum flask with reflective interior that the steak would cook, that if you stand in front of a mirror you will heat up from the reflected rays

No…That doesn’t happen because of simple conservation of energy. The steak is not producing thermal energy or receiving it from a hotter object. So, all that the reflective interior can do is slow the cooling of the steak.
The earth is receiving lots of thermal energy from a hotter object, namely the radiation that it receives from the sun. Its steady-state temperature is set by the balance of what it receives and what it emits back out into space. The greenhouse effect, by affecting the rate at which the earth emits radiation back out into space for a given surface temperature, causes the earth’s temperature to warm in order to maintain radiative balance.

or that you can save on your heating bills by filling the loft with CO2?

Insulation in general does help you to save on heating bills. The reason that CO2 in particular does not is for a variety of reasons, one being that the heat loss from a house is due to many mechanisms besides radiation. (For the earth system as a whole, the only way it can lose heat is via radiation, although heat can be transferred between different parts of the system, e.g., surface to atmosphere by convection and evaporation/condensation.) Another is that, as discussed above, the full picture of how adding CO2 affects the greenhouse effect relies on the fact of the lapse rate in the troposphere, something that is not applicable in your example.

Several commenters maintained that a colder body cannot heat a warmer body. They may have confused heat with temperature. Heat can be transferred from a cold body to a hotter body, but a colder body cannot increase the temperature or heat content of a hotter body. However, a colder body can decrease the rate of cooling of the hotter body by radiation to the hotter body. Electrons jumping orbitals and producing radiation don’t know if there is a warmer or colder body out there somewhere, therefore the total instantaneous radiation from any body is independent of the temperature of the surroundings.
Something I did not see in the comments was mention of emissivity, which would have a direct impact on the sensible temperature of the air and surface of the earth. Good emitters (high emissivity) both absorb and emit energy better (grass, leaves, black bodies) than low emitters (most light colors, stainless steel). Emissivity will vary greatly from year to year depending on snow cover, clouds, crops, deforestation, etc.
Dr. Glickstein’s discussion is interesting, but I think is too simplified to convince any warmist that CO2 is not cooking the earth.
A couple of things that I am curious about that directly affect the emissions balance, and which have not appeared in any discussion I have read, are:
1. Energy is absorbed and converted to chemical energy through photosynthesis. I have no idea how much energy that would be (probably not much), but with higher CO2 levels, vegetation is growing faster so it is logical that more radiation is being converted to plant material than in the past, which is stored energy that will not be re-emitted until the material is burned or otherwise reverts to it’s former state.
2. The earth might correct temperature variations by moderating emissions, especially in the Arctic. When the northern oceans are warmer than normal, they freeze later in the season, and since they emit to an almost perfect black body (deep space with no sunlight) they release much more heat and take up very little, esp. in winter, helping to correct the global temperature. Ice and snow are poor emitters and also insulate the warmer ocean beneath whereas a dark ocean is a very good emitter. A change in ocean currents, for example diversion of a warm pacific current to the Arctic for a prolonged period, could cause global cooling by eliminating ice in the Arctic all year. I have no idea how significant this cooling would be, but suspect it is substantial. Perversely, an abnormally warm current to the Arctic would cause warming of the atmosphere while reducing heat content in the ocean, making it appear as if the earth is warming when in fact it is cooling. Do the GCM’s address this?

Bryan,
The 2.66 grams per square inch figure is considering the whole air column.
http://www.wolframalpha.com/input/?i=14.7+lbs+*+400%2F1000000
Alan D. McIntire,
The solar radiation hitting the earths surface is 184 W/m^2 per Trenberth 2009 or 198 W/m^2 per Trenberth 1997. The surface albedo must be applied to this to get the net gain. Back radiation adds another 333 or 324 W/m^2 respectively. Since Trenberth’s diagram don’t show any reflection at these wavelengths , it is unclear whether he has applied the albedo that corresponds to these wavelengths. The albedo of surfaces varies with wavelength, and for some surfaces like snow the variation is quite significant.
If the emission from a surface is blocked from escaping in some parts of its spectral emission range, then, everything else being equal, it must increase in temperature until enough of its spectrum is in the ranges that do allow the energy to escape. That would be its equilibrium temperature. Of course, everything else isn’t equal, it will never have to reach that temperature, because conduction, evaporation, convection, poleward heat transport, etc. will assist in transporting the heat away.

The issue at hand here is not that co2 can absorb energy, but what occurs and how does it contributes to AGW, and specific man’s co2 output.
If I suspend in the middle of my room a 4 foot by 6 ft by 2 inch thick lead plate in the middle of my room (not touching the walls), then while that lead plate has huge ability to absorb energy (1000’s of times more than co2), that introduction of the lead plate will NOT cause the room to warm up. So, any energy absorbed by this lead plate will be re-emitted back into the room.
If the above lead plate could heat up the room, the we would all purchasing big lead plates to suspend in the middle of the room for free heat.
On the other hand, increasing the insulation of the WALLS of the room is a different matter.
So, at the end of the day is not that co2 can absorb energy, but what occurs with that effect. As the lead plate example shows, just because physics says something can absorb energy does not necessary mean it affects the inflows and outflows of energy in a given system.
And in fact it not the co2 that holding this energy anway, but the other substances such as ground and ocean and other parts of atmosphere that represents the bulk of the “mass” of the atmosphere to hold that heat energy.
In fact, this explains why engine blocks and especially motor cycle heads are often painted black, not silver in color. The choice of black paint on the engine can cause the engine to cool better! In other words, placing black paint on an engine block INCREASES cooling effect yet black paint is known to absorb energy better!
In effect, since black is a good absorber of energy it’s also thus becomes a good emitter of energy. Black objects emit more radiant energy (cools faster) than a white or silver to its cooler surroundings.
The issue here never been that co2 can absorb energy, but the issue is not the slam dunk as to what effect this has in terms warming the overall system, or even as some claimed can in fact cause cooling of the system based on the same reasons why black paint on engines can help cooling!
Super Turtle

It seems that for incoming sunlight there is one surface (where sunlight strikes) but for the outgoing radiation there is another surface (at the top of the atmosphere for some wavelengths). One might say that the heat that consumes time migrating from the incoming surface to the outgoing surface represents the heat of greenhouse warming.
I always wonder about the 15 degree C number quoted as the earth’s surface temperature. It seems that this is the just the air temp nearest the surface struck by sunlight (assuming I don’t misunderstand the source of the number). Why wouldn’t it be more appropriate to attempt to average all temps (air, sea, and land) inside the regions somehow touched by solar radiation (but excluding deep earth temps influenced by heat of radioactivity).

Here is an experiment to disprove the existence of back radiation.
CAUTION: Only perform with parental supervision.
CAUTION: Treat any large Fresnel lens as if it were an open flame!
CAUTION: Since this experiment is indoors, pay close attention to ANY light or infrared (IR) source, which could be focused by the lens. That includes sunlight through windows, hot kitchen stove filaments, etc.
The only thing great expense in performing this experiment with be the Fresnel lens itself. One square meter Fresnel lenses are available through science supply sites. The lens need to be a plano-convex radial lens to focus parallel rays onto a one square centimeter spot (or even down to one square millimeter). I have heard an F-stop near one is best. This gives a one ten-thousand multiplication though that will to be reduced by up to ~50% due to refraction, scattering and optical imperfections in the facets.
You will need a very small black metal cap to hold one cm³ (1 gram) of water or ice. This will be placed at the focal point of the lens. You will need an infrared (IR) heat source, a space heater, large wattage hair drier, something to add additional warmth to a wall later in the experiment. You will later need an ice cube.
Similar to:
http://www.modulatedlight.org/optical_comms/fresnel_lens_comparison.html
http://www.scientificsonline.com/large-fresnel-lens.html?&cm_mmc=Mercent-_-Google-_-NULL-_-3052833&mr:trackingCode=CC6E1735-DB81-DE11-8C0A-000423C27502&mr:referralID=NA
Now, ready? If back-radiation proponents are correct, we should be able to use this huge lens to focus back-radiation from any warm wall within your house, at the ambient room temperature of say 20 ºC (68 ºF), in some room to boil water in seconds.
Use a small flashlight to illuminate the wall and so the exact focal point can be located. At this point place the black cap with the one gram of water. Wait. If they are correct the water should evaporate quickly, even boil, for that 70 ºF wall is giving off 5.67e-8*(273K+20K)^4 or 418 Watts per square meter that is going to focus down to 400 W x 5,000 multiplication factor or 2,000,000 Watts per square centimeter and we only need 2250 Joules to vaporize that gram of water. Wait, maybe there are some loses within your setup so be patient. Wait. Don’t know about your experiment results but mine is not working. Half an hour later I gave up, something mystical is blocking all of those back radiation photons from entering that lens. Watts up with that?
Now replace the water and cap with an ice cube. it should develop a hole slowly at the focus. Here the temperature at the focus is less than the temperature of the wall and radiation flows.
But I want to see the water boil, so cover the lens and warm up that wall in front of the Fresnel lens to a much higher temperature, let’s say 104 ºF (40 ºC). The watt flux should now be something near 5.67e-8*(313K-293K)^4 = 0.009 W/m^2 or 50% efficiency of 0.009 W/m^2 x 5,0000x = 45 W/cm^2. Uncover the lens. Well, it probably won’t boil but you should now evaporate that gram of water in about 2250 J/g ÷ 45 J/s or 50 seconds if you have a perfect setup with no loses. Let’s just say in a couple of minutes.
Careful, but now fill the cap and point that heat source, directly into the lens from five or six feet away, this is why Fresnel lenses can be dangerous, the water should now boil and quickly in seconds.
Thermal radiation heat going backwards does not exist in reality, at all, if you are a scientist type and not merely a AGWChurch member, run the experiment, prove it in reality.
Sorry back-radiation lover’s, you love is just in your minds (and wrong application of Stefan-Boltzmann equation).
That is also why Fresnel lenses are not dangerous in a very warm dark room at the focus. That room is at radiative equilibrium due to everything being at the same temperature and there is, in reality, no radiation at all, or you could focus it.

DirkH;
David, this means that at -25 deg the upper atmosphere is no more colder than the ground; an equilibrium is reached. Of course, nothing happens from there; but your premise was to show that the people who say a cold object cannot warm a warm object are somehow wrong – your example shows that two equally cold objects are in equilibrium and does not contradict those people at all. In your example, the upper atmosphere is no more colder than the ground.>>>>
Read more carefully my friend. I said that at at 25,000 feet it is colder than that even at the equator. Two points:
1. According to AMSU-A http://discover.itsc.uah.edu/amsutemps/ satellite data the global average at that altitude is in the range of -38C. It would be warmer than that over the equator, and colder… much colder, over the arctic.
2. 25,000 feet isn’t “upper atmosphere”. In fact, it is only part way up the troposphere which is the lowest layer of the atmosphere. Troposphere ends at 11Km, then Stratosphere about 50Km, Mesosphere about 88Km and then the thermosphere about 500km and then the Exosphere.
Lot’s of other examples by the way. Build a house with no insulation and measure the temperature in the house and between the inner and outer walls with the furnace running at a constant rate. Then insulate the wall cavity. With the furnace running at the same rate the inside of the house will become warmer. The thermometer between the inner and outer walls will also read warmer, but still cooler than inside the house. The insulation absorbs outbound heat and reradiates it back into the house. Pile snow up around a house, and despite being colder than the inside of the house, the house gets warmer with the exact same heat sources inside, that’s how the early pioneers in NA insulated their sod shacks in the winter. That’s how the Inuit survived centuries in the far north by living the winter in igloos where the cold ice walls nonetheless kept them warmer than they would have been in the open…It’s even the same principle that a freezer works on as does an air conditioner. A kiln gets much hotter than an open fire, but put a thermometer inside the wall of the kiln and you will find that it is cooler than the temperature inside the kiln. Same with a forge. And no, these examples have nothing to do with convection, you can build a forge or a kiln with thin walls or thick walls and have the exact same air circulation, but the thick walled ones have a higher temperature inside, and the temperature of the walls is cooler.
I am a raging skeptic. An angry, they are misleading us with how they represent the results, producing results from tragically flawed and sometimes outright fraudulant “science” and are being used by lobbyists who are more interested in lining the pockets of their lobby than they are in what’s best for humanity, and I’m disgusted by the whole thing. But cold things radiate photons carrying energy and if they bump into something warmer, there are any number of factors that determine if they will be absorbed or not. But the relative temperature of the two bodies has zippo to do with it. The relative temperature of the two bodies only defines the magnitude and direction of the NET energy exchange, which can only be from warmer to cooler. But take the cooler body away, and the warmer body’s temperature must fall because it is no longer recieving any heat from the colder body.

Wayne,
For how much of the infrared black body frequency range is your Fresnel lens able to focus at that one spot? Is your lens material transparent to infrared?

Charlie Foxtrot: exactly. Well-said.
Dr. Glickstein: I appreciate your efforts to draw analogies to explain the CO2-induced warming of the Earth. However, I’m suspect the effort is doomed from the start because one cannot apply a steady-state model to a dynamic process. The Earth does indeed receive energy from the Sun, and radiates energy into space. But, the system is not at steady state due to Earth’s rotation around its axis, slight eccentricity of its orbit around the sun, greater or lesser cloudiness over time, absorption of energy into oceans or loss of energy from the oceans, and likely a host of other factors not mentioned in this list.
I’ve done a fair bit of outdoor cooking, over a campfire with a chunk of meat rotating on a spit above the fire. One would have a tough time creating a valid model of how the meat cooks using a steady-state model. Same thing applies to the Earth’s energy balance.

Martin Lewitt, it’s an experiment for you to perform, look on the specifications when your lense arrives, or better, mid-IR lens are also available, specify your choice when ordering. Let us know your results. ☺

I wish my fingers would learn that ‘lens’ is singular, ‘lenses’ are the plural. ☺

And continuing.
I would like to see the back radiation proponents do the following.
Take a spherical black body object with a small heat source in its center and shine a light on it and read the temperature.
Take the same spherical object and enclose it with a black body enclosure that does not touch the surface except at some required points to center it around it. use the same lamp at the same distance, and measure the temperature at the surface of the original sphere. Now make another black body enclosure and repeat the procedure. Do this until you have 12 layers of black body. If your argument is correct, then the temperature should sky rocket to the point of starting a fire. According to back radiation proponents statement of how it works.

Bryan says:

Readers of Ira’s last thread will know that Joel postulated that;
1. Heat can move from a colder surface to a warmer surface spontaneously.
2. Invented statements and then proceeded to attack them.
3. Has the Stephan Boltzmann equation applying to gases.

Actually, what readers of that thread will know is that Bryan is a purveyor of pseudo-science. He has absolutely no serious desire to discuss the science and, like all purveyors of pseudo-science, tries to distract people by nitpicking words…even after the wording has been corrected to everyone’s satisfaction. (See here for more discussion specifically on the tactics that Bryan, Gerlich and Tscheuschner and other purveyors of such pseudo-science employ: http://wattsupwiththat.com/2011/03/29/visualizing-the-greenhouse-effect-molecules-and-photons/#comment-649274 ) The existence of people like Bryan within the skeptic movement, willing to actively engage in such deception, certainly helps to keep you guys marginalized in the scientific realm.

3. Has the Stephan Boltzmann equation applying to gases.
…
Joels proof of the “greenhouse theory” involves getting rid of the Oceans and atmosphere.

More nonsense. Simple toy models of the greenhouse effect illustrate the concept and give one a qualitatively understanding of what is going on. Line-by-line radiations codes do the full calculations for the actual absorption lines as they exist in the atmosphere in order to nail down the effects quantitatively. Yes, the simple models don’t have all the gory details in them…That is the whole point.

Postma is absolutely correct in stating that the long wave radiation produced by the Earth system is released at an average height.
Some radiation from the ground leaves directly through the “window”.
Radiation also leaves from different heights above the surface.
The average height is about 5Km.
The lapse rate which is completely independent of the radiative effects then determines the surface temperature .

Fine…Everything you say is basically correct. The one thing that you and Postma are leaving out is what I said in my last post…that the average height of 5km is determined by the IR-absorptivity of the atmosphere, i.e., by the greenhouse gases in the atmosphere and clouds. (The technical statement is something like this: At any given wavelength, the height at which most of the radiation escapes to space is given by the height at which the “optical depth” [ http://en.wikipedia.org/wiki/Optical_depth ] of all of the atmosphere above that point to radiation of this wavelength is of order 1. More quantitative details can be found in books on atmospheric radiation, such as Ray Pierrehumbert’s book “Principles of Planetary Climate”.)

IRA: It is getting more and more conspicuous that you are completely ignoring the alternative explanations for the Earth’s temperature. You have completely ignored me and many others who have suggested some other theories to this point, unless I missed something. You need to respond. With some facts. Otherwise, my advice is to shut up.

wayne says:

William C. Gilbert’s words are much better than the ones I have been using and now I have someone to attribute them to. He’s right, it is merely not so simple, but understandable, physics.

It is clear that Gilbert has never actually read any elementary textbook on atmospheric physics or climate science or he would be aware that the argument about adiabatic lapse rate that he presents is not new to anyone in the field…It is discussed in all of these books. (Alternatively, maybe Gilbert is aware of this but is confident that the readers who he wants to convince have not.)
However, far from his claim that this temperature profile explains the 33 deg temperature difference between what is observed and what radiation balance requires, the fact is that it alone doesn’t explain any of it. You need to consider not only how the temperature varies with height but what then sets the constant that tells you what the absolute temperature is at some height in the troposphere. In the absence of absorption of terrestrial radiation by the atmosphere (and with the other caveats about still having the same albedo and such), that average temperature would have to be 255 K at the surface because of radiative balance and then the temperature would decrease with height at the lapse rate from there.

Joel:
“The errors in your explanations have now been explained to you multiple times in this thread. There is no excuse for you to continue to cling to them”
?? Can you please point me to those explanations, sir? I must have missed them, or else, perhaps, probably, most likely, they were balogne? Come on, fella, provide some tangible thing that I can relate to, instead of your Orwellian insistance that there is, “out there,” something that proves your case/argument/status/being/etc..
WTF?

ferd berple says:
May 8, 2011 at 2:24 pm
The solar radiation hitting the earths surface is 184 W/m^2 per Trenberth 2009 or 198 W/m^2 per Trenberth 1997. The surface albedo must be applied to this to get the net gain. Back radiation adds another 333 or 324 W/m^2 respectively.
There seems to be a whole lack of common sense going around these days.
So, according to T, the earth receives 184 w from the sun, radiates some of this back outwards, where some of it is absorbed by the atmosphere and re-radiated back to earth, where it provides 333 w.
In other words, 184 w ends up as 666 w, because the back radiation is omni-directional at at most 50% reaches the earth……………………………………
///////////////////////////////////////////////////////
There does appeart to be a complete lack of commonsense in these figures.
If these figures were correct (ie., back radiation is approximately twice the power of solar), why are we wasting time with trying to capture solar energy rather than back radiation energy?
Why don’t we construct a large array of mirrors collecting and focusing this back radiation much like the Californian Solar power station: see
http://greenwombat.files.wordpress.com/2010/01/esolar-power-plant.jpg
This not only would produce more energy (viz about 330 cf about 190 W/m^2; back radiation cf solar), it would additionally solve the storage problems inherent with present day green energy projects since back radiation is available day and night etc.
The answer is simple, either this back radiation does not exist, or if it does exist it is incapable of doing any sensible work (ie., it lacks sensible energy).
The lack of any serious research into collecting and utilising the back radiation energy source strongly suggests that leading energy scientists regard the back radiation set out in Trenberth’s energy diagrams to be complete and utter nonsence!
Anyone who supports Trenberth’s diagram and considers that the back radiation theory is correct should be asked to explain why we are not utilising this fanastic energy source. After all, if it existed it should be the main focus of green energy projects.

Luuuucy?????? Ira?????? we are missing some comments here. WTF? Are you THAT desperate????

While you’re at it, Dr. Noor van Andel’s paper also explains the “GHE” based upon the adiabatic lapse rate. Again, show me exactly where he is in error, citing exact quotes from the paper, without any hand waving.
http://climategate.nl/wp-content/uploads/2011/02/CO2_and_climate_v7.pdf

A warm atmosphere will emit radiation. Some of it will be backradiation.
Even without IR absorption the atmosphere will warm.
http://earthobservatory.nasa.gov/Features/EnergyBalance/page6.php
Convection.
Evaporation.
Incoming energy absorption (visible light).
With this in mind, and accepting the backradiation mechanism, how can the “greenhouse IR” component be ascribed the full 33 C difference?
Surely it can’t be?

How does this fit in with the Holographic Universe theory?

Why is “the Petty black body curves peak at a longer wavelength than the Carleton spreadsheet”?
As dr.bill said, this is because the Planck equation is actually an integral. When you change the x-axis, the peak actually does shift. I have written a full explanation at
http://mc-computing.com/Science_Facts/Blackbody/Blackbody_Equations.html
There is also a plot showing the difference in the shape of the two 300K curves and their peaks.
biological evolution has “tuned” our visual system to be most sensitive where the light energy is maximized
Not quite, that is where the intensity per wavelength interval is brightest, not where the energy per frequency interval is largest.
This demonstrates why people who believe in Global Warming always plot spectra versus wavelength. When you want to analyze the energy in the system, all plots should be versus frequency (normally expressed as a wavenumber) to show an honest plot. In that case, most of the energy from the Sun is in the IR. When plotted versus wavelength, the plots incorrectly imply that most of the energy is in the visible and UV spectra.

Ira, I’d really like some of the “back radiation” now. Just stepped outside my house in Kamloops BC and pointed an IR thermometer straight up into the sky and got a temperature reading of -10 F. When I pointed the thermometer horizontally down the street, got 34 F. Pointing it at the outside of my house gave a temperature of 44 F as did pointing it at my driveway. The airport temperature now is given as 48 F. The altitude of the airport is about 200′ lower than where I live. I should note that the sky is perfectly clear at this time with no clouds in sight (just wish it would do this in the daytime).
The surface of the earth heats up considerably during the day and this heat is released during the night. Of course having heat buffers of variable capacity greatly complicates models. The -10 F temperature that I’m seeing with my IR thermometer is the average temperature of the atmosphere from 1600′ above sea level to space. What portion of this would be related to “greenhouse gasses” and what portion is the result of heat flux from sun-warmed surface and air to space?

From the comments here, a lot of people seem to believe that the greenhouse effect cannot exist because it violates the 2nd law of thermodynamics. To my shock, I am finding myself agreeing with Joel Shore on the elementary physics. I have just finished reading the Postma essay, and it contains the same strawman argument that crops up every time this matter is discussed.
Postma described a black body warmed by a heat source and claimed that you cannot make it warmer by reflecting that emitted radiation back. Whilst acknowledging back radiation exists, he asserts that this energy cannot cause the black body to increase in temperature. He states that a body cannot raise its own temperature. Well of course not. The reason this is a strawman fallacy is because nobody is making that claim. The claim is that the back radiation reduces the rate of cooling of the earths surface because the net outflow in watts is slightly less than it would have been without the back radiation. It is the sun that causes the warming because energy is now coming in faster than it is leaving, so the temperature will rise until a new equilibriumis reached.
An analogy is a tub with a ‘V’ cut near the top. The higher the water level is above the ‘V’, the faster it flows out. This is an analogy of the SB law of blackbody radiation. Suppose the sun is represented by a running tap. The water will rise above the ‘V’ just enough so that the rate of input is equal to the rate of overflow. Let us now represent the back radiation by blocking some of the ‘V’ which represents the reduced outflow of radiation from the earths surface. The water level (temperature) will now rise such that the outflow increases to balance the inflow. If you turned the tap off (remove the sun from the climate system), the water level (temperature) would start to decline just as you would expect from thermodynamics.

“Anyone who supports Trenberth’s diagram and considers that the back radiation theory is correct should be asked to explain why we are not utilising this fanastic energy source. After all, if it existed it should be the main focus of green energy projects.”
“- If back radiation is so powerful and it is a heat source, why don’t we use it?”
Good questions. Although what about this free energy oven. Does it qualify?
http://www.slayingtheskydragon.com/en/blog/111-a-pictures-worth-a-1000-words#comments

Boris Gimbarzevsky,
Thanks for sharing your thermometer readings It would be interesting to know if on clear nights, sky readings taken at the same ambient temperature but different absolute humidities varied due to increased water vapor greenhouse effect.

Charles Nelson said: Gotcha Henry! He thinks CO2 is like a toxin in the atmosphere! An amazing toxin which is NOT TOXIC at 380ppm but suddenly BECOMES TOXIC at 400ppm. There in a single post is the fuzzy thinking of the Warmists! Fantastic. Textbook example of ‘Carbonaphobia’!
I don’t read him that way. I think he’s making the point that the tiny size of the fraction, by itself, doesn’t tell us anything. If he’s making the point that you think he’s making, he’s doing a poor job of it.

Martin Mason said – If back radiation is so powerful and it is a heat source, why don’t we use it?
Because the earth’s surface is already at the temperature to which the back-radiation has raised it.

Robert Stevenson says:
May 9, 2011 at 2:16 am
“Therefore I conclude no global warming from increasing atmospheric CO2.”
This was disproven by expermental physicist John Tyndall over 150 years ago. Back radiation from gases that absorb IR is quite real. Suggest you read the original work here (it’s free):
http://www.archive.org/details/heatconsideredas00tyndrich

We seem to have an unusually large number of comments from the anti-science brigade today who seem to have invented a whole new branch of previously unknown physics.
Imagine an ice cube, at zero degrees Celsius, alone in the vacuum of space (which is at, say, absolute zero). What happens to that ice cube? Well, it radiates away heat (as everything above absolute zero does) and eventually cools to absolute zero itself, asymptotically. Now imagine an another ice cube, this time at -10 degrees Celsius, being placed near to the original ice cube. This colder ice cube also radiates heat; some of it will impact the first ice cube and ‘warm’ it. The original ice cube still continues to cool, but not as fast as it was doing before because it now has a heat input which was not there in the first case. The colder ice cube therefore helps to keep the original ice cube warmer. Of course, it never gets above its starting value of zero degrees Celsius, but that is how the presence of cold objects can keep hot objects warmer i.e. they are still warmer than what would be in their place if they were not there (in this case the cold vacuum of space at absolute zero).
The 2nd Law of Thermodynamics? – Yes – it fully supports this – no contradictions. .

Ira – regarding your summary comment 4) at May 8, 2011 at 7:51 pm
my comment – NO, the atmosphere does NOT emit LWIR across a distribution of wavelengths like a blackbody , see my earlier comment at Dave in Delaware says: May 8, 2011 at 7:00 am
Ira Glickstein, PhD says:
“4) As I understand it, the ~15μm radiation from the Surface to the Atmosphere is absorbed by H2O and CO2 molecules which, when excited, bump into nitrogen and oxygen and other air molecules, and heat the air. The result is emission of long-wave radiation at a range of wavelengths (not just in the ~15μm region, but including the ~7μm and ~10μm regions) in random directions, some of which finds its way back down to the Surface and is re-absorbed. That conversion of a portion of the ~15μm radiation into other wavelengths may explain why there is a “bite” out of the ~15μm radiation that seems to be missing from the radiation out to Space. ”
——————————————
This is the part of your comment I disagree with –
“The result is emission of long-wave radiation at a range of wavelengths (not just in the ~15μm region, but including the ~7μm and ~10μm regions) in random directions, …”
My reply – If CO2 absorbs at 15μm, it emits at 15μm. The Nitrogen and Oxygen in the atmosphere neither absorb nor emit in the LWIR wavelengths of interest. That is why there is an Atmospheric Window – the atmosphere neither absorbs nor emits in that 10μm region.
Think about the satellite-looking-down readings – the 10μm atmospheric window corresponds to the surface temperature. Over the Sahara, the 10μm readings show a surface temperature around 320 K. Over the Mediterranean, the 10μm readings show a surface temperature around 280 K. Over the Antarctic, the 10μm readings show a surface temp just below 220 K. If the atmosphere (mostly N2 and O2) emitted LWIR like a blackbody, the atmospheric window readings would look like some middle atmosphere temperature – not like the surface. There is an Ozone band in the middle of the atmospheric window, I expect from ozone in the upper atmosphere; if N2 was emitting blackbody LWIR there should be other N2 bands in the middle of the window, and there are not.
———————————-
Ira comment – “That conversion of a portion of the ~15μm radiation into other wavelengths may explain why there is a “bite” out of the ~15μm radiation that seems to be missing from the radiation out to Space. ”
My reply – Recall that the satellite-looking-down readings are Emissions; their temperature tells us something about where those emissions originated. Looking at the CO2 band satellite 15μm readings, the temperatures are around 220 K and nearly the same for the Sahara, the Mediterranean and the Antarctic. That looks to me like the Tropopause. It does not necessarily tell me how the energy got to the Tropopause, so I am not sure I could estimate a ‘bite’ value. That emitted energy could have arrived from lower atmosphere CO2 emissions, or from atmospheric lapse type convection, or possibly from the tops of thunderstorms.
My comments are referenced to these satellite IR spectra at
http://mensch.org/5223/IRspectra.pdf
Slide (c) Western Tropical Pacific is particularly interesting because it compares ‘clear’ with ‘Thunderstorm Anvil’. Note that the CO2 band temperature is identical in the clear and thunderstorm curves. Also note that the atmospheric window 10μm region temperatures are MUCH DIFFERENT for clear vs thunderstorm anvil. This suggests to me that while the atmosphere does not emit like a black body, the thunderstorm (liquid water) does.
Best regards to Ira – I hope my comments are constructive and instructive, and will help your ‘mental models’ and descriptions.

Circa 1850 Tyndall experiments with greenhouse gases in a nutshell.
Radiation flow:
heat_lamp -> -> adjustable shade -> salt crystal window -> mirrored tube filled with test gas -> salt crystal window -> adjustable shade -> galvanometer
Tyndal ran literally thousands of experiments with different gases and mixtures at different pressures, different infrared light sources, and different lengths of tubes. His setup took up a lot of space but I marvel at the cleverness he used to increase accuracy and precision using the technology of the day. His analog gear was so sensitive he read the reading from the galvinometer through a telescope because getting a warm body anywhere near the experiment mucked it up.
His best most stable lamp was a black painted face of a vessel filled with boiling water. His galvanometer response is not linear so the primary purpose of the adjustable shades was keep the radiative energy input to the face of the galvanometer in a range where you got maximum needle deflection from minimal change in radiation.
In lectures he used to take his galvanometer to the podium in the hall. He’d point it at a blank wall on the other side of the hall and ask someone from the audience to walk over to that wall. The galanometer needle would move dramatically when a person entered the scene.
Anyhow Tyndall found a great many gasses, most famously water vapor, that would dramatically lower the galvanmeter reading when present in the tube versus the same mixture without it. He also used some rather ingenious ways of processing his gasses prior to filling the tube with them including means of completely drying a sample of the atmosphere.
If one wants to dispute the concept of back radiation one must first explain why Tyndall’s galvanometer would read progressively lower as the absolute humidity of the atmospheric sample in the tube rose. No one will. Every attempt is fatally flawed in some way. Tyndall didn’t discover anything that wasn’t already predicted by the theoretical physics of the day. He confirmed the theory via experiment or in other words he was doing science the way it’s supposed to be done.
Tyndall did discover some things that no one had worked through on paper at the time. One notable thing he discovered was the non-linear absorptive response as the partial pressure of an IR-absorbing gas went up. He found it to be linear at the lowest partial pressures then progressing to exponential or in other words when it comes to IR absorbing gasses increasing the amount of it is a case of diminishing returns after a certain amount.
This is why the climate boffins talk about CO2 doublings and temperature rise. At the current atmospheric CO2 partial pressure its absorptive response is in the exponential range. The linear response range is all below the first 100ppm. It’s sort of like people picking low hanging fruit in an apple orchard. They can all pick as fast as they can for a while but as the number of people picking increases at some point they’ll be competing with each other for the same low hanging fruit. So putting more pickers in the orchard will always increase the rate at which fruit is picked but at some point it becomes a case of diminishing returns.

Charles Higley says:
May 7, 2011 at 9:33 pm
“It should also be pointed out that, as CO2 partitions 50 to 1 into the oceans, we would have to emit 50 times more CO2 that required to simply double atmospheric CO2. There is not enough carbon available to do this. If we really tried, we might be able to do 20%.”
It could also be pointed out that CO2 partitions 100,000 to 1 between the rocks and the air, so we would have to add 100,000 times more CO2 to just double atmospherics CO2…
This is wrong, as the ocean comparison is wrong because of time-scales. It takes the oceans centuries if not millenia to absorb additional CO2 so that partitioning will take effect eventually, for rcok/air the timescales are more like millions of years…

Dave Springer says:
May 9, 2011 at 5:57 am
RJ says:
May 9, 2011 at 1:41 am
“Anyone who supports Trenberth’s diagram and considers that the back radiation theory is correct should be asked to explain why we are not utilising this fanastic energy source. After all, if it existed it should be the main focus of green energy projects.”
“- If back radiation is so powerful and it is a heat source, why don’t we use it?”
Good questions. Although what about this free energy oven. Does it qualify?
We do use it all the time. One example is the smudge pots used to limit freeze damage in orange and avocado groves. The heat of the smoke from the smudge pots is inconsequential. The effect comes from the black carbon particles in the smoke which absorb upwelling IR from the ground and send a portion of it downwards and sideways. It works as an insulator. This is the same mechanism by which CO2 molecules insulate. Anyone who contests this is simply wrong and needs to take an introductory class in physics.
———–
Dave, you and I structurally disagree, but end at the same conclusion. To me, and I am sure it is correct by physics, is the effect comes from the black carbon particles in the smoke which absorb upwelling IR from the ground increases the temperature at that altitiude (10 m) and by SB using delta T (LBL if you want) between the surface and these particles decreases the upward flux making it warmer than it would have been without the carbon particles in this thin layer where the smoke is.
You do not need a special kind of “back radiation” that flows from cold to hot to explain it, it only scrambles minds away from what is actually happening. If you care about people’s minds at all, stop wording it like you just did. There is no special radiation called “back radiation” or “backward radiation”.

ferd berple says:
May 9, 2011 at 8:11 am

Here is a reference showing that Jupiter has 60K higher temperature than expected.
33K higher than expected on earth. 60K higher than expected on Jupiter. Co-incidence?
http://burro.astr.cwru.edu/stu/advanced/jupiter.html
•As seen in the table below, the average temperature of Jupiter is approximately 160 K. However, due to the equation for thermal equilibrium (below), it should only be about 100 K.

“This extra heat is generated due to gravitational contraction – the planet is slowly shrinking in diameter. This way, by compressing by only a few millimeters every year, it can generate heat by increasing the pressure of its constituent gas.”
So Ferd, is it your assertion that the earth and venus are shrinking? I already explained to you that temperature only increases during the process of compression and the earth, Venus, and Mars (unlike Jupiter) aren’t shrinking.
What part of that don’t you understand?
Let me fix that for you by adding the explanation for the extra warmth on Jupiter from the article you quote:

Wayne
If you want a bit deeper understanding of the radiative energy flow one needs to understand that all matter above absolute zero radiates and where there are two bodies at different temperatures there’s a net transfer of energy between the two from warmer to colder. The net transfer rate is all the matters for most practical concerns but at the deeper level the radiative transfer goes two ways. The warm object doesn’t stop the cold object from radiating so energy from the cold object is indeed reaching the warm object just as energy from the warm object reaches the colder one. It’s simply a matter of the colder object receiving more energy from the warmer than the warm object receives from the colder.
That doesn’t seem like proverbial rocket science to me but you may perhaps be right that it might as well be rocket science for many people.