Hi John,
I'm gonna start at the end, and work backwards.
"Since IR does not contribute to to the temperature of air...." -JMR
Okay, I guess you mean that the oxygen/nitrogen part of our atmosphere is transparent to IR. That is true.
"...it also does not contribute to the kinetic energy of molecules. " -JMR
Ever?
Not even CO2 (which then itself, heats the air)?
I'm not sure how to take this. You've mentioned "kinetic energy" before, and I provided some information about your use of the phrase, which should have precluded this most recent remark.
If you're considering kinetic energy only as "translational vibration" (moving from one place to another and bumping into things), then you're missing all the "rotational" and "stretching" vibrational modes that gas molecules have. It is these vibrations that are equated with CO2's absorbed IR at 4-5 microns.
Eventually, if these vibrations are not transmitted to another air molecule (by bumping it), the vibrational energy will be re-emitted (to be re-absorbed locally, if not escaping unimpeded into space).
Maybe there should be a thread on "Energy, kinetic and potential." Does the above make sense?
So, with this understanding of "kinetic energy," yes; your statement "Temperature is the measure of kinetic energy of atoms and molecules," is true.
Have you read somewhere that IR (4-100 microns) does not contribute to the kinetic energy of air, or CO2, or any gas molecule?
I'd like to see such a link....
===
Okay, now on that first paragraph, about the greenhouse stuff....
Firstly, there's a big difference between the effect of a glass greenhouse, and CO2's "greenhouse effect."
They are analogous, but not the same; not even similar in their mechanism of heating action, as glass is opaque to IR, and CO2 is nearly invisible (except at 4-5 microns and above 13 microns).
Secondly, when you say, "It is suggsted that if you increase the level of CO2 in a greenhouse...." are you talking about CO2 inside of a glass structure?
If so, why; there nothing about it in that link, nor is there any real-world analog in our climate.
I'm not trying to be obtuse, but that was all I could get out of that first paragraph; you actually use the word 'structure' in that sentence about CO2.
Thirdly, do you have any other link(s) about this? Your link to a blog about a century old article in which the author himself, after making some comparative observations in his garden, concludes with:
"I do not pretent to have gone very deeply into the matter, and publish this note merely to draw attention to the fact that trapped radiation
appears to play but a very small part in the actual cases...." -R. W. Wood [final paragraph]
...and the OP goes on to say,
"I present the full text, although the second-to-last paragraph is (in my opinion) regrettable and wrong." -link
...again, there's nothing about CO2 on this 1909 link of yours.
...and that American Institute of Physics link does have all these common misunderstandings spelled out and answered.
...any questions? I'll be happy to answer....
...also, just fyi....
You asked, what I am talking about?
It's been 25 years since my degree in Chemistry, but I don't think the principles of physical chemistry or instrumental analysis have changed too much. I may be wrong about something or, more likely, I left something out; but I'm pretty sure the end result is correct.
Are there any chemists or physicists who think CO2 doesn't absorb IR as the spectra show?
Well, this is way too much talking (although shorter than the average college lecture); but this is a complicated subject (they pay people to teach this stuff, y'know), so it shouldn't be too surprising.
~SA
