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Re: Laws of Thermodyamics

If memory serves me correctly this explanation, or something very similar, was presented in one of the textbooks we had when I was at grammar school in the late 1960s.
The mechanism makes complete sense from a feed back point of view, the standard AGW models are frankly impossible being tuned to a very narrow stability range with a vastly inadequate gain loop. Interestingly the mechanism is essentially that by which a Stirling engine operates.

Having at one time been, allegedly, expert in thermal imaging I find the continual harping on about CO2 absorption driving AGW more than a little annoying. Within the thermal imaging community it has always been axiomatic that CO2 band transmission falls to essentially zero over path lengths between 1 1/2 and 2 1/2 miles depending on altitude, weather conditions and who's measurements you choose to use. Hence all CO2 band radiation is already absorbed within the troposphere so further additions have no effect. If there had been any useful transmission in the CO2 bands the thermal imaging community would be exploiting it. A couple of decades ago I was able to demonstrate, as part of an investigation into inexpensive short range IR systems, that exploiting this part of the spectrum gave sufficient performance gains to allow un-cooled detectors to be used but the effective range proved, in practice, to be marginal for the application.

Clive

Re: Laws of Thermodyamics

Thanks for that, Clive.
If I wasn't convinced before that the CO2/GW argument is nonsensical, I certainly am now.

Re: Laws of Thermodyamics

Clive,

Do you perhaps have any references for the path length of CO2 absorption?
I know that, sooner or later, it's going to crop up in discussion, so it would be nice to have something solid to point to.

Re: Laws of Thermodyamics

Peter
I have a note that the 1 1/2 mile figure can be found in Infra Red Systems Engineering by Hudson but a quick skim though my copy hasn't located it. I shall have to find time to sit down and read it properly again. The longer estimate would have been derived from data in either or both the Handbook of Military Infra Red Technology or its multi volume successor The Infra Red Handbook (title?). Most likely the latter given the period when I did the work. Unfortunately I don't have a copy of The Infra Red Handbook so I can't check (worst £50 I ever saved was turning down an offer of the last stand copy about 5 minutes before an exhibition ended!) and the data in my copy of the Handbook of Military Infra Red Technology doesn't look sufficiently familiar. although there is at least one suitable graph from which the extinction co-efficient can be derived and hence absorption path length estimated.

I managed to get a sight of the current Infra Red & EO Handbook but couldn't see any simple statements there. Sorry.

Clive

Re: Laws of Thermodyamics

Thanks, Clive.

I'll try to source one of those publications - or get a friend to do it for me ;-)