December 5, 2010 at 10:11 amSo it is generally accepted that a doubling of atmospheric CO2 will lead to a rise of 1C? That certainly agrees with the model calculation (admittedly a simplified one for illustrative purposes) in the textbook of Atmospheric Physics and Chemistry on my shelves. The book goes on to say that in the current state of knowledge, any definite statement about feedback is pure speculation: for example, there are dramatic differences between the effects of high and low cloud cover. """" : for example, there are dramatic differences between the effects of high and low cloud cover. ""How so ?? Well the first thing we can dispense with is that ANY H2O, in ANY PHASE, at ANY ALTITUDE, ANYWHERE on earth, will ALWAYS diminish the total amount of solar energy that reaches the planets surface.In Step #1, cloud albedo component (ANY CLOUD ANYWHERE) reflects solar spectrum Radiant energy back into space from the tops of the clouds, by a process of Optical scattering. In addition H2O VAPOR ALWAYS captures part of the solar spectrum incoming energy, in the wavelength range from 750nm to around 4.0 microns; and that component could be as much as 20% of the total solar spectrum energy (in humid tropical regions). And most of that lost solar radiation would have gone deep in the oceans; which are to a large extent in the tropical and Temperature zones, where there is lots of sunlight; so that is a loss of ocean stored energy.In step #2, that portion of the solar energy input that was captured by H2O (and ALSO that smaller amount captured by CO2 in the 2.7 micron band) results in ENHANCED warming of the ATMOSPHERE. That eventually leads to INCREASED atmospheric radiation of LWIR thermal spectrum Radiation; BUT : that radiation is essentially isotropic, so only half of it reaches the surface; while the other half is lost to space.The result of #1 and #2, is a NET loss (ALWAYS) of incoming solar energy reaching earths surface and getting stored; mostly in the oceans. But that is not all that happens. The extra LWIR radiation from solar energy that DOES reach the ocean surface; is absobed (99%) in the top 50 microns of sea water, which will result in localised surface warming which will result in rather prompt EXTRA evaporation of warmer surface molecules, which also carry of with them a whole lot of latent heat of evqaporation, which will ultimately be dumped out (about 590 Cal/gm) at high altitudes; where convection currents transport the moist air to. Another 80 cal/gm is available to be deposited likely even higher if the water droplets then freeze and form ice crystals.So some fraction of the half of the H2O captured solar energy (CO2 too ) that strikes the surface is immediately transported to high altitudes for radiation to space.So the net result is that ALL H2O anywhere in any form in the atmosphere ALWAYS reduces the amount of solar spectrum energy from the sun, that gets absorbed by the earth.There is virtually no other significant source of energy on earth but the total solar input. Atmospheric captures such as the GHG effect of H2O, and CO2 molecules can further delay the exit of LWIR energy from the surface; but they cant stop it, and they dont increase the total amount of energy the earth absorbs; it is ALWAYS less than what would be absorbed by the earth if the atmospheric GHG gases were totally absent; primarily, H2O, CO2, and O3.So whatever the GHG effect and clouds may do in messing around with surface or atmospheric LWIR radiation; that cannot increase the energy over and above the amount that the sun delivered in the first place.Over longer times like the IPCCs 30 year climate interval; any increase in GHGs (H2O, CO2, and O3); all of which capture INCOMING SOLAR SPECTRUM ENERGY must result in overall cooling. There cannot be other than overall cooling resulting from a net decrease in the total amount of solar energy absorbed by the earth.As to the overall effect of the LWIR emissions from either the surface or the atmosphere (including clouds) those processes are Optically lossy; since the emission processes are highly diffuse; and hence very low optical transmission efficiency. Cloud height^4 decay rates, or Cos^4, and Cos^8 obliquity factors add to the lossiness for LWIR energy getting returned to the earth surface and absorbed somehow.The thermal processes, and absorptions for solar spectrum energy, and LWIR energy from GHGs are quite different; and you cant simply add them as if they were the same animal.As to cloud height; the higher the cloud, the less H2O it contains, so the amount of LWIR or solar energy captured by the cloud goes down, so that enhances the loss of LWIR to space, and reduces the solar energy loss to the surface. So yes; higher clouds block less sunlight, so more sunlight reaches the surface; but it is always less than the zero cloud case; but by the same token, the absorption of outgoing LWIR by those higher and wispier clouds goes down as the cloud height increases; so the GHG effect of higher clouds is always less than for lower clouds.Just where the modellers get off treating this as positive feedback is totally beyond me; but it seems that they take that as a starting assumption in their models. No wonder; they dont get the right answer.As for generally accepting that a CO2 doubling raises the Temperature by one deg C; it is quite true that this is accepted by those who accept it; but not by those who dont accept that; absent any evidence to that effect (from planet earth).So proof would be welcome to replace the general acceptance.

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