sci.energy

On Mon, 13 Aug 2007 15:53:26 -0700, Bill Ward
wrote:

>I think that question is still up for grabs. There's no doubt it all
>must be radiated, but from exactly which levels and by what seems obscure.

Doesn't the temperature gradient with altitude show that?

>What would be the effect? It seems to me space should just look like a
>3K black body. What am I missing?

The atmosphere? Radiation flux of anything below room
temperature has to be fairly low. If the outgoing radiation of an
object (ignore the incoming for this) is related to the temperature,
it must be related to the relative velocity of the molecules and in some
way to the mean free path.

This is where there is a lot of science assumed simply on the
basis of the writings from the 1800s.

It isn't clear that those authors of the 1800s papers knew
that temperature decreases with altitude in a very regular way (ignoring
the relatively rare occurrence of temperature inversion).
And it isn't clear if those authors from the 1800s knew the
temperature depends on the velocity of molecules or any relation to the
mean free path.

It is almost certain (in my opinion) they did not know that
the speed of sound in a specified gas is almost totally dependent on
temperature, because sound cannot be transferred from molecule to
molecule faster than the molecules travel. Since the atmosphere is
air (with trace gases), pressure pretty much falls out of the equation
to calculate the speed of sound (all air is pretty much the same).
It is not unusual to find an expert aerospace scientist that
doesn't know the speed of sound in the atmosphere is dependent mostly
on temperature.

With the lower temperatures at altitude, the radiation must
also depend to some extent on altitude, but the longer mean free paths
at altitude may allow IR radiation to proceed easier.
While the surface of the Earth may radiate at many or any IR
frequency, the atmosphere must radiate at specific frequencies, but
with greater altitude, the longer mean free path must enhance the
outward radiation away from purely omnidirectional.

And a good mathematical description of the radiation
complex should show that outward radiation dominates for both the
reasons of higher temperature at low altitude and because of the longer
mean free path at higher altitudes, plus the mathematical summation of
the spherical Earth.

An important point possibly overlooked is the fact that in
the atmosphere, a maximum high arises regardless of the amount of
sunlight and the clearness of the atmosphere.
That means radiation and convection increase more rapidly
with only slightly higher temperatures.
The record maximum of about 134 F in dry desert areas gives
a good indication of the possible radiation and convection mechanisms,
apparently without any of the effects of evaporative cooling by water
vapor.

How long will the gossip fad go on before papers specific
to IR radiation by the surface, the atmosphere and the various trace
gases reveal exactly what the effect of CO2 is.

I can only guess about two more years, depending on how the
2008 US election goes.