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Old October 12th 03, 03:30 AM
JimC
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This is an interesting discussion. I wonder if there might be some mixing
of terms that is adding to the confusion. Let's see if we can agree on a
few basics and take it from there.

The dominant part of the sun's emissions that supplies heating to the earth
is in the infrared end of the spectrum. While there are materials that
approach being 100% IR transmissive, water is not one of them. IR is
quickly absorbed in water. This is evidenced by the spectrum of light
present as water thickness is increased. For example, the deeper part of a
swimming pool appears bluer than the shallow part because the sun's light
has transition through more water, 2 x the depth, before reaching our eyes.
The deeper the water, the bluer and darker it looks (provided the water is
clear).

Does a cloud absorb IR radiation? Well, it's made up of water and water
absorbs IR. The answer is yes, clouds absorb IR radiation. If you have any
doubt, think of being outside on a hot day and what happens to the heat you
feel from the sun when a cloud passes overhead. The heat on your skin from
the sun drops significantly if the there is any thickness to the cloud.

This does not refute the thermal satellite imagery in any way. The
satellite imagery shows IR emissions. The earth's surface is much warmer
than the cloud tops and the earth has pretty high IR emissivity. It
registers as warmer due to its higher IR emissions.

Temperature vs altitude within clouds is a different matter and is affected
by several factors, some of which, like convective cooling, may overwhelm
the others.

Just another 2 cents into the discussion.

JimC

"Bob Gardner" wrote in message
news:54Ihb.536556$cF.207547@rwcrnsc53...
Here's another picture to look at:

http://www.nws.noaa.gov/sat_tab.html

Bob Gardner

"john cop" wrote in message
om...
"Bob Gardner" wrote in message

news:GwAhb.535167$cF.206989@rwcrnsc53...
Look at any text on the atmosphere and you will learn that temperature
decreases with altitude, cloud cover not withstanding (absent an

inversion).
The sun does not heat clouds.


Look, I am no atmospheric expert, but the above is just a plain silly
statement (less charitable types might say stupid). What do you think
happens to all that energy? It ALL get reflected back into space?

Clouds, which you should know even from just from watching the weather
on TV, are insulators of sorts. This means that the sun's energy (the
part that doesn't get reflected) get absorbed by the cloud as it is
transmitted through it. If were an ideal insulating situation, the
temp gradation would be linear, but, obviously, its not (gas laws and
all that), but the principle is the same. My bet is the energy
transfer to the clouds is greatest at the tops and reduces with
altitude according to some unknowable (too many variables) function.
If your statement were correct, the temp at the tops would be the same
during the day as during the night which is, I think, silly. This
does not mean the temp is going to rise as you climb (gas laws again).
What is does mean is that the cloud's capacity to absorb moisture (or
supper cooled stuff) very near the tops could be substantially greater
than near the bottoms.