Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information....

Atmospheric pressure

This example uses calculus.

Gases, unlike liquids, are quite compressible, and at a given temperature, the density of a gas is approximately proportional to the pressure. The proportionality constant is discussed in section A.2, but for now let's just call it k, ρ = kP. Using this fact, we can find the variation of atmospheric pressure with altitude, assuming constant temperature:

Pressure falls off exponentially with height. There is no sharp cutoff to the atmosphere, but the exponential gets extremely small by the time you're ten or a hundred miles up.

Last Update: 2010-11-11