Re: RC: Re: Climate and Altitude changes

[CMKSAGEHIL@aol.com]

In a message dated 9/7/00 2:12:36 PM Pacific Daylight Time, 
suendavid@worldnet.att.net writes:

<< The oxygen is NOT thinner at altitude, there is just as much of it at 
20,000
 ft as there is at sea level.  The difference is that there is less
 *pressure* at altitude to help drive it across the lung membranes and into
 circulation.  >>

Thank you, Ben Turner, for setting this straight.  The pressure on a gas 
dictates how many molecules of that gas are present in a given volume.  There 
is less pressure at higher altitude, therefore there are less molecules of 
"air" (although the relative percentage of oxygen remains somewhat stable) in 
any given volume, period.  And that phenomenon of basic physics is what is 
more commonly referred to as the air being thinner at higher elevations.  So 
there are two factors at work here in terms of the physics on the air side of 
the equation--sure, less pressure to help "drive" oxygen across membranes, 
but yep, also "thinner" air!

Heidi