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Temperature of a gas is based on the relative
velocity of the atoms/molecules - so where the air is thin the average velocity
of the molecules is much higher because they don't "bump" into other molecules
as frequently. So once you leave the troposphere, the temperature
starts to increase at some point and continues to increase into
space.
In outer space the "temperature" is in the thousands
(or more degrees) - but because the density is so very low there is not any
"heat" content to mention in a cubic unit of air - so no risk of frying our
astronauts (at least due to ambient temperature)
As you go lower, the air becomes denser, the average
velocity of the air molecule slows down (temperature drops) and even though the
air mass per cubic unit is increasing, the drop in velocity causes
the ambient temperature to become colder.
.
At least that is best I recall if from long
ago
Ed
Sent: Monday, October 15, 2012 2:54 PM
Subject: [FlyRotary] Re:
skydivers-supersonic-24-mile-jump
Jarrett Johnson < hjjohnson@sasktel.net>
wrote: """
Some of that temp rise will be aerodynamic heating. I know at
280knts and
24,000ft I'm seeing 10-15decC rise in temp... At 800+mph the
temp rise would
be a lot higher, even at 70K+ ft.
"""
Airspeed definitely wasn't the case here.. this was during the
ascent, when he was rising about 1000fpm, maybe less (don't remember exactly)
but his speed over the ground had by then diminished to 15-20 knots, just
floating along with the flow up there. I, too, am curious about why
ambient temps started to rise as altitude increased... I'd have figured it to
just keep going down right in step with the ambient pressure. It'll be way
interesting to hear the actual reason.
<marv>
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