E-mail exchange with son-in-law:

GJW: I wish to touch this issue once more.
First, my [earlier] sentence was badly written: "No one will argue that CO2 contributes significantly to the insulating effect of the atmosphere". I meant to agree with you, meaning one would "argue" i.e. "try to defend" the position that CO2 contributes significantly to the insulating effect.

ACS: I still disagree. The whole position of the CO2 enthusiasts is that CO2 in the atmosphere allows incoming radiation from the sun without any insulating effect of the CO2 at that time. However, radiation from the Earth to outer space is later impeded by the insulating effect of CO2.

GJW: I am beginning to think the word "insulating" is not getting to the issue. And recall that the claim is that other wavelengths than IR are what are "converted" at the earth's surface into IR re-radiated toward space, so that CO2 would in fact absorb incoming IR but would allow other wavelengths to pass.

ACS: The word "insulating" does get at the issue. It means retard passage and that is the essence of the 'greenhouse" claim. Greenhousers say CO2 in the atmosphere retards passage of heat from Earth to outer space.
There are two mechanisms by which the greenhouse theory could work. Atmospheric CO2 would have to allow all incoming radiation to strike the Earth's surface but not allow heat or any radiation associated with heat to escape. Or, all heat or radiation associated with it from incoming radiation is absorbed and regenerated as heat. We know this second one is false by the example of the green house, wherein heat is generated within the structure.

GJW: I am not sure I agree that Infrared radiation is heat, which is what you seem to imply. It is electromagnetic radiation, like light or UV or X-ray, and generates kinetic energy of molecules that absorb it. So the white and black surfaces differ in their absorption and reflection, and they may also differ in their consequent radiation of Infrared, but that infrared is not heat and has to strike another molecule to excite and generate heat.

ACS: OK. We need not argue about whether infrared radiation is heat. The point is that the sun's radiation is composed of many wavelengths of energy which are delivered to the Earth. At least some of those wavelengths are converted to heat. Take a greenhouse, which appears to be a traditional example. The sun's radiation travels through the transparent atmosphere and the transparent glass or plastic covering of the greenhouse, without any apparent heating of the atmosphere or the glass/plastic. The radiation than strikes nontransparent services. Some of these are black or mixtures of black-and-white and are able to convert the incoming radiation to heat. Pure white surfaces are apparently reflective and any radiation striking those services tends to bounce, until it finds a surface which can convert the convertible portion of radiation to heat.
I have no difficulty with the mechanism you describe. It is not really dissimilar to what I have said. Infrared or other portions of the electromagnetic spectrum are all energy, some of which can be converted to heat by striking certain substance molecules. Other nontransparent molecules can convert a portion of the electromagnetic spectrum into electrons (photovoltaics). If a molecule becomes "excited" by absorption of an energy quantum, that is only a temporary situation. That molecule will return to a steady state by loss of the energy quantum, and the energy quantum is available for conversion to heat, if it has not already done so.

GJW: if this is true, then the gases that can absorb IR light are the ones that "trap" what is re-radiated from the earth. In this case "trap" means absorb and release heat into the atmosphere.

ACS: I agree that the previous paragraph is true, but what you have just said is not. If CO2 is a "trap" gas, it will absorb incoming IR from the Sun and convert it to heat it at that time. It would not wait for the conversion until the IR has been reflected and is now on its way to outer space.

GJW: This point is moot because as I mentioned above it is other wavelengths that are "converted" and re-radiated as IR that are in question.

ACS: I don't think it is moot, because we are talking about heat and any radiation that acts as a source of this heat. Non-reactive radiation wave lengths are irrelevant.

GJW: CO2, Water, Methane, etc, can absorb IR while O2 and N2 do not, and this absorptivity, not thermal conductivity, is what greenhouse effect is about.

ACS: I believe this part is really important. Let's say water and methane are similar to CO2 and just talk about CO2. If a molecule of CO2 absorbs a quantum of IR, the molecule is excited on a temporary basis. It will return to its steady state by either releasing the quantum of IR unchanged or converting the quantum of IR to another form of energy, such as heat.
You say 02 and N2 do not do that. I suspect you have no basis for that claim.

GJW: Well there is a theoretical basis which is fairly compelling to me just now. I have inserted something off the web below. See what you think.

ACS: I have read it. An interesting theory to explain a result, which is only speculation. His last sentence says, "This is the mechanism by which greenhouse gases absorb energy from infrared photons." But, what is the new nature of the now infrared photon activated CO2 molecule? Is the activation temporary? How short the duration of activation? What is the molecule doing in the activated state? Bouncing around more? Does that generate heat from friction with other molecules? Consider the gas laws and gas theory. As molecules get hotter, they are said to move faster. We know that they pound harder on a container wall; increased pressure.
All this doesn't really tell us anything. Let's track the heat. We could get some facts by going back to to the experiment I previously cited. Irradiate different gases and measure their temperatures before and after radiation.
It would also be illogical that there would be a plus or minus effect. You might be partially correct in saying that CO2 has a greater propensity to absorb and convert IR to heat than does oxygen or nitrogen. However, this could be easily demonstrated in the laboratory. Take an enclosed volume of pure CO2, shoot it with IR, and measure the CO2 temperature. Do the same with 02, N2, or any other gas. I suspect you will find a slight rise in temperature for all of them. CO2 may give the most rise, but then we have to discuss the fact that CO2 is present in the atmosphere only to the extent of 0.038%. We also have to go back to the previous (third) statement involving why CO2 in the atmosphere would not have converted incoming IR to heat, rather than wait until the IR was outgoing.

GJW: I sure would like to get this all sorted out.

ACS: I don't believe this can be sorted out at the present time. Only time will give an appropriate resolution. This would be akin to the round versus flat Earth in Galileo's time.

GJW: Under a separate email I am sending an article on new ideas for cooling the troposphere. (if needed)

ACS: I've covered that separately. It is mostly silly.