AT LAST - Latent heat is "it"..

[Derek]

Hi All,

I came across this thread at Dr. Judith Curry's blog, Climate etc.
Tropospheric and surface temperatures
Posted on October 29, 2011 by curryja
by Donald Rapp

I particularly noted Fred Moolten's comments,
ie,
" I have a sense Donald Rapp, perhaps inadvertently, has created the impression that
tropospheric amplification is a creation of climate models – it’s not,
but rather follows from the basic Clausius-Clapeyron relationship
– nor is it a fingerprint of anthropogenic warming but
also follows from surface warming from other forcings such as solar.
In other words, if the surface warms, the mid- to upper troposphere should
warm somewhat faster in the absence of some anomalous upper tropospheric phenomenon
regardless of why the surface has warmed, and so
it doesn’t distinguish between causes of surface warming.
Multiple techniques have been employed to measure this, and differ in their conclusions, but
it’s fair to say that the faster warming, if it exists, has not been clearly demonstrated. "

and,
" The mechanism leading to a prediction of tropospheric amplification is
increased evaporation of water from a heated surface regardless of the cause.
When the increased water vapor reaches colder (higher) altitudes, it condenses,
releasing more in the way of latent heat and thus leading to a warmer upper troposphere.

The high altitude absorption of IR by CO2 contributes to the overall atmospheric and surface warming, but
does not disproportionately warm higher altitudes.
In fact, the reverse is true – an increase in CO2-mediated warming will often disproportionately warm lower altitudes, but
this disproportion is erased by upward convection of warm air so that the original lapse rate (temperature change with altitude) is restored.
It is therefore the latent heat release that creates disproportionate warming aloft. "

and,
" I should add that it’s not clear to me what are the relative contributions of different mechanisms
to the tendency of a warmed atmosphere to require upward convection to erase the instability due to low altitude warming
(also, it is not invariable in all circumstances).
Among the contributors should be the increased buoyancy of air that is richer in water vapor
(i.e, closer to a surface value for relative humidity),
as well as the low altitude warming effect of increased water vapor itself via IR absorption.
In general, the convective effect appears to be predicted mainly in atmospheres with a water vapor component (or equivalent), and
with lapse rates that are determined by the condensible component such as water vapor.
An atmosphere with CO2 as the only IR absorber would be expected to behave differently. "

Please excuse my emphasis using large text size within the above quotes.....

[Richard111]

No problems with most of that. It all follows the clear sky adiabatic lapse rate theory. When water vapour condenses it also markedly reduces local air pressure which creates impressive updrafts within the clouds. These updrafts transport the released latent heat upwards far in excess of the now reduced saturated adiabatic lapse rate. Talk to any pilot about updrafts in clouds.

Why else is the tropopause higher at the equator than at the poles? Of course the air is warmer at 10 kilometres altitude at the equator than at the poles, but that doesn't qualify for a hotspot.

One point I would disagree with:

Quote:The high altitude absorption of IR by CO2 contributes to the overall atmospheric and surface warming, but does not disproportionately warm higher altitudes.

My emphasis. CO2 absorbs in all three bands when the sun is shining. The surface is shielded from those bands. THUS CO2 IS NOT WARMING THE SURFACE IN THE DAYTIME. It is warming the atmosphere sure, but the adiabatic lapse rate does not permit "hot spots".

As for CO2 warming the surface at night when all it can only absorb is the 15 micron band which constitutes just 5% of the total upwelling radiation AND uses 2/3 of that absorbed energy to warm the atmosphere leaving just 1/3 to be isotropically radiated such that just 1/2 might reach the surface.

For 100% upwelling radiation, blackbody/graybody the CO2 doesn't care, it just absorbs its assigned 5%. 1/6th of that or 0.8% of the total upwelling radiation might reach the surface because of CO2 in the atmosphere. Big deal!

Sorry, I become irritated when I read "CO2 warms the surface".

[Derek]

Richard111 wrote,
" Sorry, I become irritated when I read "CO2 warms the surface". "

Me very much too Richard111, but I "skipped over it" because of the far more important, perfectly reasonable, makes sense in reality, points he is making,
that I, and I would be brave enough to say you too, agree with very strongly.

There are times I get hopeful "we" will get through this politically motivated mess, presently called "consensus climate science",
which it ain't....