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Re: air blowing out of an old mine





On Wed, 16 Sep 1998 16:22:33 -0700 (PDT) jmclean@chem.ucsd.edu (James
Mclean) writes:
Herbert H Gottlieb says:

Please explain. Why should air blow DOWN a mine shaft during the
summer? In the summer the air is warm.

The outside air is warm, but the mine shaft air is cool, and hence
more dense.
Imagine replacing the cool air in the shaft with an even denser fluid.
What happens when you take a vertical tube full of water, and then
remove the endcaps?

But mine shafts are often hotter at the bottom than at the surface.
Wouldn't the air become heated at the bottom and become
less dense than the air at the surface?

What happens when you take a vertical tube of helium gas and then
remove the endcaps?

Herb Gottlieb