Let's see if someone can find the error in my reasoning here:
1. Blackbodies absorb all incident radiation.
2. Blackbodies absorb and re-emit incident radiation below their cut-off frequency.
3. Blackbodies absorb and turn into heat energy radiation above their cut-off frequency.
Imagine a 300K blackbody surrounded by a perfect mirror, itself at 300K.
The radiation emitted from the blackbody is reflected by the mirror back onto the blackbody. The radiation emitted from the mirror (due to itself being at 300K) is also incident on the blackbody.
The blackbody despite having more than twice the incident radiation cannot heat up past 300K because this would require a 300+K body being heated by a 300K body -- a violation of the second law of thermodynamics.
The best that could be said for a warming effect here is that if the temperature of the blackbody were to fall, then it would be 're-heated' by its own rays trapped in the cavity. So if anything this is a radiative insulator but definitely not a heater.
OK so what does this have to do with AGW?
Well if the surface of the earth is a blackbody and it radiates as such into space, and the atmosphere contains CO2 which absorbs and re-emits 15 micron (and other wavelengths), then we have a similar situation to the above thought experiment, with a couple of important differences:
1. CO2 absorbs and re-emits in both directions. For each incident photon there is a 50% chance it will be ejected to space or emitted back down to the ground.
2. CO2 is not a blackbody itself. (Only dense media behave like blackbodies).
The idea that the earth emits infrared radiation toward the sky which 'back-radiates' it down to earth producing a heating effect is purely fictional. As we have just seen this can't happen due to the second law. At best it could behave as a radiative insulator. However the fact that for each 'reflection' 50% is lost to space would suggest that after just three or four 'bounces' there would be nothing left of the back-radiation, and since this only takes a fraction of a second to occur one cannot say that there is any effect on surface temperature by the presence of a CO2 layer at all.
So to recap:
1. A body cannot be heated by its own reflected rays.
2. CO2 absorbs and re-emits in both directions, sending back as much as 50% of the bands it absorbs.
3. The earth cannot be heated by 'back-radiation' from CO2.
4. Any energy trapped in this system would take a fraction of a second to escape so the CO2 cannot act as a radiative insulator.
Replies from people who understand the physics only please!
Credit goes to Sythe. SYTHE OR GTFO
So many views and not a single reply. Come on, I'm trying to further activity in this section but you guys are not assisting me in the slightest. Let us see how smart your "geniuses" really are, FK. I'm looking at you @Leader, @"Cann!bal", and @Michael (Since you own a P&D group.)
Good luck boys.
1. Blackbodies absorb all incident radiation.
2. Blackbodies absorb and re-emit incident radiation below their cut-off frequency.
3. Blackbodies absorb and turn into heat energy radiation above their cut-off frequency.
Imagine a 300K blackbody surrounded by a perfect mirror, itself at 300K.
The radiation emitted from the blackbody is reflected by the mirror back onto the blackbody. The radiation emitted from the mirror (due to itself being at 300K) is also incident on the blackbody.
The blackbody despite having more than twice the incident radiation cannot heat up past 300K because this would require a 300+K body being heated by a 300K body -- a violation of the second law of thermodynamics.
The best that could be said for a warming effect here is that if the temperature of the blackbody were to fall, then it would be 're-heated' by its own rays trapped in the cavity. So if anything this is a radiative insulator but definitely not a heater.
OK so what does this have to do with AGW?
Well if the surface of the earth is a blackbody and it radiates as such into space, and the atmosphere contains CO2 which absorbs and re-emits 15 micron (and other wavelengths), then we have a similar situation to the above thought experiment, with a couple of important differences:
1. CO2 absorbs and re-emits in both directions. For each incident photon there is a 50% chance it will be ejected to space or emitted back down to the ground.
2. CO2 is not a blackbody itself. (Only dense media behave like blackbodies).
The idea that the earth emits infrared radiation toward the sky which 'back-radiates' it down to earth producing a heating effect is purely fictional. As we have just seen this can't happen due to the second law. At best it could behave as a radiative insulator. However the fact that for each 'reflection' 50% is lost to space would suggest that after just three or four 'bounces' there would be nothing left of the back-radiation, and since this only takes a fraction of a second to occur one cannot say that there is any effect on surface temperature by the presence of a CO2 layer at all.
So to recap:
1. A body cannot be heated by its own reflected rays.
2. CO2 absorbs and re-emits in both directions, sending back as much as 50% of the bands it absorbs.
3. The earth cannot be heated by 'back-radiation' from CO2.
4. Any energy trapped in this system would take a fraction of a second to escape so the CO2 cannot act as a radiative insulator.
Replies from people who understand the physics only please!
Credit goes to Sythe. SYTHE OR GTFO
So many views and not a single reply. Come on, I'm trying to further activity in this section but you guys are not assisting me in the slightest. Let us see how smart your "geniuses" really are, FK. I'm looking at you @Leader, @"Cann!bal", and @Michael (Since you own a P&D group.)
Good luck boys.
