The interesting thing about that photo is that the clouds are different from the open sea, and that there is a slight difference between land and sea (you can vaguely see the outlines of the countries). Not sure what or if the colours map to, but interesting all the same.

The Earth in 'IR'

Doesn't look like a glass of milk to me. It looks complicated.

I found a couple of estimates of mean free path for a photon in air. 11 feet or 33 metres. Thatt's within an order of magnitude, so it will do. One source gave 11,000 'bounces' on the way to TOA. So if it was a few more, what difference does it make? (I am not doubting CO2 radiative physics, but given that it is happening so much, how does a bit more CO2 make a difference?) It has had 11000 bounces, but it got out of the top in (est) one fiftieth of a millisecond. And millions of chances to thermalise some stray molecule. So we'd take the chances of NOT thermalising and raise that to the power of the number of potential collisions. And to see the effect of an increase in density we'd raise that power to some larger number. I would guess that the increased chance of thermalising was small. If you haven't thermalised something by now I don't care how much you raise the TOA. Now, that can be checked by CERES or something like it. Find the missing energy in the CO2 bands and see which other bands are carrying that energy, because it all has to add up to the same total. Now Harries et al 2001, a paper I keep returning to, did some of that work and failed to go to completion. One of their findings was that the minor CO2 waveband was not changing over time. They didn't mention it, nor did they attempt to translate the units of measurement into any likely heating result. Missed opportunity? Or inconvenient result? There must be a lot of info in the satellite data, but climate folks don't make much of it. And suspicious ole me wonders why.

Well done Martin, you have demonstrated that not one of those outfits can provide an explanation that stands examination. There is no trapped heat. Outgoing equals incoming, over time. Now I appreciate that condition could be met with a redistribution of heat causing an increase in surface temp, but that is not what is described above. And I hate all those uselss beggars who present things in averages first. It is entirely bogus when you are dealing with fourth powers.

(I'm sorry to appear perverse, awkward or resistant, but it is necessary to put the theory to a proper test.)

Rhoda,

The probability of an IR photon thermalizing a GHG molecule on the way up through the atmosphere is related to the number of GHG molecules there. If you increase them, you increase the chances of a collision. Obviously this relationship is logarithmic, to get the same additional effect you have to add exponentially more GHG molecules, and this is almost the same as saying

So if it was a few more, what difference does it make? (I am not doubting CO2 radiative physics, but given that it is happening so much, how does a bit more CO2 make a difference?)

But the 'bit more' does make a difference, because we are not talking about a 'bit more', climate sensitivity always talks about a doubling. If we double the existing number of CO2 molecules, that is more than just a 'few more'. H2O is about 0.4% of the atmosphere, and CO2 about 0.038% (about ten times less) so doubling CO2 increases the number of GHG molecules by about 8.5% roughly. This would correspond to more collisions, longer path length, more chance for thermalizing diatomics through kinetic collision. Higher temperature.

As an exercise to enrage the pedants and taking the 8.5% guesstimate way beyond its useful usage, 8.5% of 33K is 2.8K. Obviously climate sensitivity depends on much more than a simple arithmetic comparison of numbers of molecules, but interesting all the same.

Also, don't confuse the official "explanations designed to "convince the idiots" that the official channels puts out as representing the science in any way.

I'm talking about the chance of not thermalising. If thermalising is on the whole likely, how many photons get through? Get all the way to TOA without such a collision. Now, we know thermalising IS likely at current concentrations. Otherwise there wouldn't be a greenhouse effect. So not many photons get through. It is they and only they who can provide more heating. And most of them will hit H2O first. We don't need to guess, the satellite data has it all. But I for one cannot interpret that data to show what is going on. You'd think it would provide an ideal basis for a test.

Or if somebody can show an ample oversupply of photons and there's always more around to thermalise. That would be in the satellite data too.

I reserve the right to mock the official explanations. The mere fact that they appear to be trying to fool me is justification enough. But I do allow the possibility that they believe this stuff.

"Doesn't look like a glass of milk to me. It looks complicated."

It is!

"I found a couple of estimates of mean free path for a photon in air. 11 feet or 33 metres. Thatt's within an order of magnitude, so it will do."

Did you get those the right way round?

That's interesting! Have you ever seen those police helicopter TV shows where they chase some miscreant across the countryside following the suspect with infrared heat-sensing cameras? The way the people glow white from the body heat? How do those work, if the average photon path length is 33 metres? Are the helicopters limited to ~100 m range or something?

Let me know when you figure it out - genuinely curious. :-)

Rhoda, if at height h in the stratosphere the concentration of CO2 molecules is some nominal X, do you accept that after doubling the % CO2 in the atmosphere h will increase for the same X? It all hangs on this.

On there being no trapped heat, as a metaphor for what is going on it is useful, as it is easily understood by lay people. When you say, "There is no trapped heat. Outgoing equals incoming, over time", you are talking about equilibrium conditions in which there is a balance. If that balance is disturbed by an increase in CO2 and a consequent rasing of the effective height of emission, radiation to space decreases and heat accumulates in the system until the equilibrium is restored with higher surface temperatures. Higher temperature means more heat content; in other words some extra heat is retained, or trapped, in the system.

In the lwir band. If you have a better mean path, what is it? I am at the mercy of google. However I do know that mean free path is not optical depth.

"I am at the mercy of google."

Aren't we all?

I already said I wasn't sure, and don't have the time/inclination at the moment to chase it down. I'm just practicing scepticism - you say mean free path is on the order of tens of metres. At the same time, we are both also aware that heat-sensing cameras work over hundreds of metres at least, with crystal-clear imagery. As you say, optical depth isn't the same thing, but they're surely related. So how can this be? Does it add up?

I can think of several possibilities. I'm not saying your MFP figure is necessarily wrong. I do suspect that if it's right it doesn't mean quite what it appears to.

But I think on this occasion I'll leave it to you lot to figure out. :-)

Sometimes in science you get asked questions, instead of asking them.

rhoda,

It might make more sense if you think of GHGs as the coolant in a refrigerator. GHGs are the only way the atmosphere in general can heat or cool. Ignoring the ones which get away out of the TOA, GHG molecules convert outbound IR photons into kinetic energy (heat) in the diatomics (O2,N2) which make up the majority of the atmosphere. They also convert diatomic kinetic energy into IR photons in the cooling phase. There is also some kinetic energy in the thermalized GHG molecules as well. Agreed?

If you increase the number of GHG molecules, this makes it more efficient as a heater/cooler. The air heats up in the morning quicker, it also cools in the night quicker. Unfortunately the heating curve and the cooling curve are not symmetrical. Graph to demonstrate"

The heating one, having an effectively infinite supply of IR photons which it formerly couldn't thermalize, now thermalizes like mad - it quickly reaches its maximum capacity. The rate of heating is only governed by the number of GHG molecules around. The air heats at its maximum rate, which is quicker if there are more of them.

On the cooling phase, there is no high-energy driver to cool. It's simply the Stefan-Boltzmann equation - basically entropic heat loss to open space - again the number of GHGs molecules is a factor in the rate, but so is the temperature of the air - the driver to cool is smaller, so the tail is almost as long as it was with the low GHG. Having more GHGs steepens the descent a little, but not as much as it steepened the heating. The system was much quicker to heat, but only a little bit quicker to cool.

If you take the heating-static-cooling graph of the air for the low GHG and high GHG scenarios, then you would see that the area under the graph is larger for the high GHG one. The area under the graph is a measure of 'heat within the system' - the temperature will be higher for such a system.

The mechanism is still radiative, but this explanation avoids the term back-radiation which annoys some people.

Martin,

I deliberately left other mechanisms (evaporation, conduction, convection, condensation in this case) out of the picture because we were focussing in on the GHE. I was trying to isolate the effect of GHG to demonstrate it can cause a temperature rise - all other things excluded.

Obviously (since I'm here on this site) I believe there are other vectors on temperature which counteract the rise produced by increases in GHGs, and fact create a dampening feedback on the GHE that has allowed out atmosphere to survive all sorts of volcanism, continent-wide fire, meteorite strike etc. over millions of years.

If the GHE (or whatever actually caused the 80s-90s temperature rise) creates a bit more temperature, we will get more evaporation, more clouds, more cooling, more albedo. It's a stable equilibrium. I'm not saying we won't get a few more rainstorms and a bit of ice melt (climate change) as things stabilize, but long-term it is unlikely to cause the sorts of problems that the alarmists feel compelled to warn us about.

Martin, if the planet is hotter due to GHGs then the GHGs hve effectively trapped heat. You can play word games and talk about mice all you want (and I know people want to, just like laying down the law about the meaning of 'evidence' or 'acidification' or even 'evolution') but trapping heat is a useful metaphor. If you outlaw the use of metaphor to make things understandable then you lose a useful tool - that is a problem unless your aim is expressly *not* to make things understandable.

"...why someone would apparently think that CO2 concentration is a function of height" - are you saying you think that from my roof top up to the international space station, the concentration of CO2 molecules remains constant? What about oxygen - think they can stick their heads out and breath? You don't think that there are rather more near my roof than up there? Or that if you double the number of CO2 molecules overall that the height of the CO2 envelope around earth will rise?

TBYJ, " GHGs are the only way the atmosphere in general can heat or cool" - see SoD link posted earlier:

Note 2 – 99% of solar radiation has a wavelength <4μm. In these wavelengths, actually about 1/3 of solar radiation is absorbed in the atmosphere. By contrast, most of the terrestrial radiation, with a wavelength >4μm, is absorbed in the atmosphere.

Maybe SoD is only a simple school teacher, but I expect the above is right.

Oops, missed a note:

Note 1 – An important exception is O2 absorbing solar radiation high up above the troposphere (lower atmosphere). But O2 does not absorb significant amounts of terrestrial radiation.

Raff,

27% roughly. This is because solar insolation is a spectrum, and the tail end of it overlaps with the absorption spectrum of GHGs. It makes no difference to the explanation. Whether IR from the sun thermalizes the ground, then the air, or the air directly makes no difference to the argument. It's the GHGs wot done it.,

Seems I don't understand any better than Rhoda, I just didn't know it. But if CO2 levels are 400ppm at the ISS and beyond (presumably, as there's nothing special about the ISS altitude) I can't see how the heat ever gets out.

Raff,

because that 400ppm is spread out over a larger volume the higher you go. At the ISS, you may only have a few hundred CO2 molecules around, but it's still at a concentration of 400ppm because all gases are spread out at that height.

RKS, it's been discussed HERE in far greater detail too :) Rhoda specifically wanted to re-do it, though.