Re: air blowing out of an old mine

[jmclean@chem.ucsd.edu (James Mclean)]

Herbert H Gottlieb says:
> In which part of the earth's interior is the temperature 58 F?
A few meters below the surface.

Every time I have toured a cave (admittedly not extremely often, and only
within a narrow range of latitudes), a big deal is made about how the
temperature in the cave is a constant temperature, not varying with the
seasons.  The temperature always seems to be in the 50's (F), although I
don't remember any specific numbers.  Bring a sweater, but not a down
jacket.

I have always assumed that this was mainly due to the earth acting as a
very large thermal resevoir, averaging the daily and seasonal temperature
variations.  Now, I'm not so sure.  Are caves in the tropics cool, or near
the average air temperature?  How far down does the permafrost extend in
Antarctica?

In any case, the expected effect on air is clear.  In a mine with multiple
openings at different heights, it should blow down in the summer and up in
the winter.  Now whether that matches the observed behavior is another
question!!!

-- 
--James McLean
jmclean@chem.ucsd.edu
post doc
UC San Diego, Chemistry

Where the temperature doesn't vary much seasonally, even the air
temperature.