Shielding (sigh, again.) and radiation dose

--- In spacesettlers@y..., rmenich@m... wrote:
>[snip]
> Weight, as I recall, is mass times 'g'. So I don't think you could
at Denver have half the mass of the atmosphere below you. Denver is
not at 18,000 feet. The only way you could have that is if you were
at an altitude where the pressure is half that of sea level.
>
> Educate me, please.

I'll give it a try, but you really need calculus to fully understand.

You are correct about weight. The problem is that gas pressure is not
linear. As you go up, the density of the atmosphere decreases. If
you picture the column of air as a series of balloons with equal
masses of air inside, the ones at the bottom will be made smaller by
the weight of all the balloons on top. At half the pressure, a balloon
will be roughly twice as tall. The other columns around it will
restrict, but not eliminate, expansion in a horizontal plane. This
restriction will increase the pressure in the balloon beyond simply
what is due to the mass of all the balloons above it.

I hope that helps -- I'll probably need to dig out a
physics-with-calculus text to explain better.

--JohnWheeler