Climate nutters

Originally posted by DanMachine: ↑

>Why in Sam Hill do you think CO2 stops absorbing IR at 280K (7C)?

I don't think that. It certainly absorbs less than at 200k.
Gah. I'm asking questions in the wrong way because you continue to insult me.
You keep thinking I'm somehow a """climate denier"""" which makes you seem liable to be insulting and hostile, which makes me insulting and hostile.

Look. Let me rephrase this.

I think many believe that the back-radiation from CO2 acts somewhat similar to glass in a greenhouse. This is only partially correct. It is a very very small effect.

The reason this is incorrect is that as the air temperature increases (yes Scott due to conduction and then convection), the effective emission height "floor" of CO2 increases. Additionally, the density of CO2 alters its radiative properties.

I'm going to (massively) oversimplify this for convenience of explanation, but, as the air temperature increases, the amount of atmosphere in the greater incidence bands decrease - and at the higher altitudes the incidence angles of the back radiation increases and less hits the earth. (The circles are CO2 molecules at different altitudes). Additionally as the altitude increases, the density of CO2 decreases, so there is relatively less IR being emitted per square metre.

(And before you say... but then this effect decreases with a higher CO2 concentration, well, not exactly but that's another story entirely, which we can go into but lets solve this one first -that greenhouses gases have no effect on surface temperatures at noon.).

So, back to the glass analogy, the difference between glass and CO2 is that CO2 can transmit the IR away from the earths surface. If infrared is absorbed by a CO2 molecule, it can either go back towards the earth or into space. Glass traps the heat in the greenhouse by insulating, CO2 is not insulating the earth. It is acting like an infrared heatsink, for want of a better analogy

So.. I'm sure that at certain times of day/ air temperatures CO2 could have a slight increase on surface temperatures, but, again, at noon? It would be an interesting set of circumstances.

(And what I've described is also the reason why the CO2 greenhouse effect is effective at night - as the atmosphere cools and the bands of ideal CO2 IR emission altitude decreases, more back radiation goes towards the earth. )

My overarching point is that people misinterpret "1.5 degrees of warming" to mean "45 degree daily peaks are now 46.5 degrees". This is impossible and not supported by data or physics.

You can confirm yourself by looking at actual Tmax data.

>The coldest places on earth are ice caps, which have very high reflectivity. See, I can take statements out of context too.
And also low insolation. I took nothing out of context.

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Ok. Now we're getting somewhere.

If infrared is absorbed by a CO2 molecule, it can either go back towards the earth or into space.

This is the fundamental point I think we are disagreeing on. If an infrared photon is absorbed by a CO2 molecule, and the CO2 molecule collides with another molecule before it re-emits the photon, the rotational or molecular vibrational energy will be converted to translational energy and therefore heat the atmosphere.

In the lower atmosphere especially, where the mean time between collisions is less than the absorption and re-emission time, this means that the atmosphere is heated slightly more during the day when there are more greenhouse gases in the atmosphere. The atmosphere is transparent enough that heaps of IR radiation makes it to the surface. Hell, even heaps of THz radiation makes it down here from the Sun, and THz is massively absorbed by Earth's atmosphere.

Is this the major driver for climate change? No, of course not, and I never said it was. This all started when you made an assertion that there was no way CO2 could increase surface temperatures at noon. I said, yes there was and tried to explain the mechanism whereby it does.

My overarching point is that people misinterpret "1.5 degrees of warming" to mean "45 degree daily peaks are now 46.5 degrees". This is impossible and not supported by data or physics.

But I never made this point.

So.. I'm sure that at certain times of day/ air temperatures CO2 could have a slight increase on surface temperatures, but, again, at noon? It would be an interesting set of circumstances.

From your diagrams, I'm starting to think less that you actually mean noon, but more "noon at a point on the earth's surface which is perpendicular to the incoming solar radiation". So missing big areas of longitude. Is that correct? Either way, I still disagree due to the reasons I described above.

I don't think that. It certainly absorbs less than at 200k.
I'd really like to know why you think this about CO2? Which physical effect are you referring to here? Is it Kirchoff's law you're interpreting this way?