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## Atmospheric pressure at high altitude

Besides, weather maps - the ones with isobars that is - would look really, really ugly if they showed the actual pressure. I mean, how could any Californian make sense of such a map???
 Blog Entries: 2 Recognitions: Gold Member Moreover, the aviation standards require sea-level-corrected air pressure to calibrate the good old barometric altimeters. Although it seems nice to see zero altitude when departing from Mexico city but that would lead to big surprises when landing on LA or Colorado Springs
 What would be the atmospheric pressure in Kg on 1cm square?

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 Quote by tumor What would be the atmospheric pressure in Kg on 1cm square?
That's a strange choice of units, but about 1.0.
 Recognitions: Gold Member Homework Help Science Advisor "kg/cm2 strange?" Check gauges on whatever regulators are handy --- output side usually includes this rather peculiar "metric engineering unit."

 Quote by russ_watters That's a strange choice of units, but about 1.0.
Actually, measuring density in mass/area isn't that uncommon, especially in radiation and particle physics. Usually this is referred to as "mass thickness", and e.g. with radiation shielding is a method of determining the amount of matter needed to attenuate gamma rays (independent of the density of the specific material, be it lead, iron, wood, etc...).

It frequently comes up in particle physics in any atmospheric experiments, e.g. cosmic ray showers and/or atmospheric neutrino expts.
 I'd ask the same question from the tech point: at what temperature water boils in Mexico city?
 Here is code I use. It gives pressure = 78,500 Pascals at 2000 meters. REM =============================== Rzero=6378100 ! Earth radius in meters R=Rzero g=9.81 Pzero=100760 ! pressure in Pascals at sea level P=Pzero Dzero=1.28 !Density of air at 0 deg C, kilograms per cubic meter D=Dzero dR=+1 ! going up 1 meter DO D=Dzero*P/Pzero ! ideal gas, const temperature R=R+dR g=9.81*(Rzero/R)^2 P=P-dR*D*g LOOP while R