John - KD5YI wrote:


Again, I'm not sure "temperature" is the relevant measure for something
like that. You can define temperature for a very low pressure gas like
this, but it's not in the same sort of sense as one would apply to a
bulk tangible medium (like air at the Earth's surface or water)

Isaac Asimov touched on this in his book on physics. He said the
temperature up there is high because of the high molecule velocity, but
that *heat* is another matter. So, you can have a high "temperature"
even if the "heat" is practically nil.


I suppose, too, that the whole things still works in terms of, say,
propagation velocity of sound, because that is driven by velocity of
molecules/atoms (and is related to square root of Temperature).

So, sound propagates very quickly in the ionosphere (it's got a fairly
high temperature), but because there's not a whole lot of atoms around,
the attenuation will be quite high (essentially infinite, I suspect)

And that's totally different than propagating something by EM waves.



That makes you correct. One must carefully state what is meant by
temperature and what is meant by heat.