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Talk:Science of global warming (view source)
Revision as of 02:55, October 20, 2007
, 02:55, October 20, 2007→Section Needed on the Saturation Problem
Incidentally, the chief oversimplification I'm making is treating greenhouse effect as linear with the number of photons absorbed. In fact, the function is frequency dependent, and not necessarily in a very understandible way. Because the energy of a photon is related to its frequency, and because absorbed photons are re-emitted as photons of other frequencies, you'd almost have to emperically measure the emission spectrum from excited atmospheric CO2 over time, frequency by frequency throughout its absorbtion spectrum, to build up a model that accurately reflects how much energy is actually retained over time by CO2 when it absorbs a photon. Again, I've found no scholarship addressing the frequency dependence of CO2's contribution to the greenhouse effect. This appears to be a gaping hole in the state of climatology. [[User:QBeam]] Oct. 19, 2007 5:11 (EDT)
Incidentally, the chief oversimplification I'm making is treating greenhouse effect as linear with the number of photons absorbed. In fact, the function is frequency dependent, and not necessarily in a very understandible way. Because the energy of a photon is related to its frequency, and because absorbed photons are re-emitted as photons of other frequencies, you'd almost have to emperically measure the emission spectrum from excited atmospheric CO2 over time, frequency by frequency throughout its absorbtion spectrum, to build up a model that accurately reflects how much energy is actually retained over time by CO2 when it absorbs a photon. Again, I've found no scholarship addressing the frequency dependence of CO2's contribution to the greenhouse effect. This appears to be a gaping hole in the state of climatology. [[User:QBeam]] Oct. 19, 2007 5:11 (EDT)
:I'm confused what you are trying to say, let me see if I understand it.
:First of all, it's weird to talk about absorbing photons in this case, because that implies some sort of step mechanism. In fact, absorbed radiation causes resonance vibrations in the bonds of molecules (the oxygen-carbon double bond, in the case of carbon dioxide). This doesn't really change what you are saing, but I thought it should be said before we go further.
:So, adding that correction to your argument, I agree with your point (1) above, with the caveat that it does not "delay" the heat radiated to the atmosphere, but partially blocks it. Statement (2) is kind of correct, there is a theoretical maximum to the ''percentage'' (not necessarily the amount) of radiation absorbed, however there are a lot of other interesting effects that come into play. For example, changing the surface temperature of the earth changes its blackbody radiation emission spectrum. There are also interesting effects like the phase of water (Venus only has a runaway greenhouse effect because it doesn't have enough water!). You've completely lost me on point (3) however. Whatever dependence temperature has on CO<sub>2</sub>, it's not based on a logarithm just because; it comes from an energy balance. Most likely whatever you are reading has simplified it in order to make it easy to talk about the affect of increasing CO<sub>2</sub>. I'm not sure where the logistic function comes in at all.
:I'm also completely lost on your last couple paragraphs. Are you trying to say that we do not understand how CO<sub>2</sub> absorbs radiation? Because we understand it really well (I've done it in intro-level college chem lab). All this talk of photons makes me think that you are confusing global warming with a luminescent effect. Also, are you trying to say that climate change models don't take into account the fact that CO<sub>2</sub> only absorbs in certain waveleghts? That's the only way global warming works! If we assumed that CO<sub>2</sub> absorbs *all* radiation, then it would absorb ''incoming'' radiation as well, which leads to global ''cooling'', not global warming. In fact, greenhouse gases pass the high frequency radiation from the sun and absorb the low frequency radiation from the earth -- if you haven't found any scholarship addressing this issue, I have a text book to recommend!
:I'd like to stress that I'm not trying to be argumentive, I'm trying to understand what you are saying. [[User:HelpJazz|Help]][[User talk:HelpJazz|Jazz]] 22:55, 19 October 2007 (EDT)