great thread. great links. great comments. here is a link that may aid in the understanding of dependence of the greenhouse effect on altitude…
Clive – thank you for spelling out the crux of the AGM argument (as I understand your explanation – a decrease in radiative energy loss with decreasing T as one goes higher in the atmosphere). What about the decrease in absorption that occurs as the temperature drops because of a reduction in doppler broadening (sharpening of the IR absorption band)? I am not qualified to comment but I found William Happer’s lecture where he cites spectroscopy experiments conducted using weather balloons very compelling.
Richard and Clive thanks for posts. Can anyone direct me to original papers about energy transfers in gas, particularly the atmosphere. At a basic level what happens to an energised gas molecule? How long does an individual molecule retain energy and how much of that energy is dissipated via collisions and how much radiated? If a CO2 molecule collides with an N2 molecule how much energy transfers to the N2 molecule and how is that transferred energy then dissipated? There must be half lives for energy retention. Does energy transferred to N2 then eventually radiate to space at a different frequency to CO2 frequency? My understanding is that in a gas energy principally transfers through collisions and only small proportions through radiation, so given the ratio of CO2 to N2 and O2 it would seem likely that most radiative energy absorbed by CO2 would quickly transfer to other molecules and ultimately be re-emitted in another wavelength?
Yes that’s right. Although radiative energy is transferred upwards through collisions, this is not the reason for the lapse rate. The lapse rate is caused by convection. In a sense the atmosphere is a heat engine powered by the sun. Heat from the surface flows through the atmosphere to the tropopause where it radiates to space. The amount of CO2 and water vapour determines the height at which the mean free path for absorption is larger than the atmosphere above it. That (average) height is at 255K to balance energy in and out. If the height increases then so must the surface temperature. All things equal it increases by about 1C for each doubling of CO2. So if CO2 quadrupled to over 1000 ppm the tee rapture would rise by 2C
Another thought I have had since it has been such a cold May and June in Scotland is that since convection is the principal mechanism for energy transfers in the atmosphere, any heating in the lower atmosphere will be counter balanced by cold currents descending from the upper atmosphere. Rather than warming being a consequence of heating, more wind would be the effect? Is the earth getting windier?
Nitrogen and Oxygen are diatomic molecules whereas CO2, Ozone and H2O are triatomic. This changes the wavelength of the vibrational modes. CO2, H2O and O3 lie all within the thermal (planck) spectrum for earth temperatures whereas O2 and N2 are are much shorter wavelengths – typical of those on the surface of the sun. This means that CO2, H2O and O3 all get excited by thermal energy in the atmosphere compared to a tiny number of O2 and N2 molecules. They emit and absorb IR photons in thermal equilibrium with the surrounding air molecules.
But only for energy radiated by CO2. Energy radiated by all other gasses is from exactly the same level as before because we aren’t increasing the quantity of O2 and N2 in the atmosphere.
“As CO2 concentrations increase so this level shifts to higher levels in the atmosphere since a critical density must be reached for the radiation to escape”
Let me point out that the amount of electromagnetic energy, whether incoming or outgoing, converted into atmospheric heating (next to the major portion which is via surface contact) is many orders of magnitude greater for H2O in the form of vapour or liquid than by CO2. The absorption bandwidth for a water droplet is, dependent on size, virtually continuous. As increasing earth temperature increases both forms of H2O, it is clear the greenhouse gas theory does not need CO2 to cause global warming! The fact is, earth’s temperature is stabilised by H2O the reason being that water droplets radiate energy according to the atmospheric temperature. Also, more water vapour means more cloud cover – and incidentally more reflection and re-radiation as well. Sorry folks, the climate is changing because urbanisation/industrialisation is draining the earth’s surface and reducing the production of vapour. It would be a start for the author here to recant the T^4 relation for CO2 emissions, or any dry atmospheric gas, – gases simply cannot radiate significant amounts spontaneously at atmospheric temperature. It would also add to the discussion to note that a blanket does not keep you warm in any way which is related to the atmosphere, it prevents the energy generated internally in the body from escaping by a thermal barrier, that is what raises bodily temperature. And to fit thermodynamics theory, energy is being temporarily displaced downwind from earth’s industrial belts so that when the polar region has got up to speed, the radiation balance will be restored – albeit with a man made pattern for the climate and some direct contribution from internal conversions – eg carbon and nuclear generators.
The temperature at a given height up to about 10,000 m is determined by thermodynamics – the adiabatic (moist) lapse rate and not by radiation. This scale is set by the surface temperature. The air thins out with height until IR photons emitted by H2O, CO2 or O3 can escape to space. This cools off the top of the troposphere and sets the scale. The earth remains approximately in energy balance so that the energy lost to space equals the absorbed incoming solar radiation. This effectively determines the temperature of the ‘top of the troposphere/atmosphere’ and equals 255K. The surface temperature approximately is then determined by the lapse rate.
The carbon dioxide heat trap is far more serious than current thinking assumes. Hopefully this is wrong. It is hard to argue for many long daily sea surface temperature and salinity measurements and ice volumes
The latest full text articles are online at:
1) doi: 10.13140/RG.2.1.2201.6169, or .
2) doi: 10.13140/RG.2.1.1415.1843, or .
An Imperial College physicist with 50 years publication record has recently shown that Pacific warming was +3C in 2014 and likely +4C by 2016. Climate sensitivity is a nonsense. The doubling CO2 heat trap is also seen in the exponential doubling decrease in Arctic floating ice volumes.