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Re: Hot air rising



On Wed, 21 Jul 1999, Leigh Palmer wrote:

At 2:02 PM -0700 7/21/99, Robert A Cohen wrote:

When the atmosphere is well-mixed (oops, I mean "characterized by
large-scale vertical exchanges of air such that conservative properties
are equalized"), the vertical temperature profile is observed to be
adiabatic. See yesterday evening's sounding at Topeka, for example
(adiabatic from surface to about 1.8 km or so). A simple model (as far as
I can tell) that is explained by a casual observation.

You miss my point. The casual observation to which I refer is that the
temperature varies as measured by my thermometer as I climb the mountain.
In the case I cited it rises, reflecting a real temperature inversion.
I can't parse your last sentence otherwise than to infer you thought I
said that one explains things *by* casual observation. Flying a radio-
sonde is not a casual observation, if that's what you intended here. I
want students to understand what they perceive in the everyday world
around them which, in this era, includes thermometers on cars. It will
soon include such things as GPS receivers, and when it does I will want
my students to understand them, too. I have taught my interested majors
how color TV works (including the psychophysics, colorimetry, and NTSC
frequency interlace multiplexing). Color TV is easier to understand
than, say, climate!

I used the radiosonde data only because I don't have the data from your
thermometer. I assume that the temperature inversion is seen in the
morning on your way up the mountain (when "mixing"* is at a minimum). Do
you see the same inversion in the afternoon when you come back down the
mountain (when "mixing"* is at a maximum)?

You should add to your qualification "well-mixed" the qualification
"and unsaturated". Latent heat* will play no role in that case, and
the adiabatic model is appropriate.

Yes. Sloppiness on my part again.

*I hope everyone knows what I mean by now; apologies to the pedants.

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| Robert Cohen Department of Physics |
| East Stroudsburg University |
| bbq@esu.edu East Stroudsburg, PA 18301 |
| http://www.esu.edu/~bbq/ (570) 422-3428 |
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