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The atmospheric pressure calculator is supplied as part of the PowerCalc Cyclists Power Calculator
STOP PRESS! THE ALTITUDE CALCULATOR HAS BEEN UPGRADED (Click here for details)
Atmospheric pressure at a given altitude (height above sea level) is calculated as follows:
p = p0 exp(-Mgy/RT)Where:
| p = | corrected pressure (mb) |
| p0 = | Pressure at sea level (normally about 1013mb) |
| y = | Altitude (metres above sea level) |
| R = | Gas constant, J/mole.K |
| M = | Molar mass of air |
| T = | Temperature (degrees Kelvin) |
| g = | Gravitational constant |
The atmospheric pressure calculator has three pairs of text boxes to allow Altitude, Temperature, and Pressure at sea level to be varied independently.
On the right side of the window; the red cube represents the volume of a mole of air at STP. The black cube represents the volume that the same amount of air will occupy - this is the one that shrinks and grows as you adjust temperature and altitude. Below is the same thing represented numerically in litres. The volume of n moles of a gas is calculated as follows:
V = (nRT)/pBelow that appears the concentration of oxygen in grammes per litre. About 21% of the air you breath is oxygen, the remainder is about 78% Nitrogen, the remaining 1% is a variety of gasses. Only the oxygen content is important providing the remaining gasses are inert (like nitrogen). Not enough oxygen and you will die.
The 'Nitrogen tent equivalent' is the proportions of oxygen and nitrogen that mixed together at sea level will simulate the oxygen content of air at a given altitude.
An IBM compatible ‘386 or better, running Windows 3.1x, or Windows 9x
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Designed by Nigel Jones