- #1

brotherbobby

- 421

- 107

- TL;DR Summary
- Is there a way to determine how air density varies with height? We all know that it falls, but what is the relation. I am looking for a function like ##\rho_{\text{air}}(x)## where ##x## is the height from the earth's surface.

Using the ideal gas equation ##PV = nRT\Rightarrow PV = \frac{m}{M} RT## where ##m,M## are the mass and molecular weights of the gas respectively.

This yields ##\frac{m}{V} = \frac{PM}{RT} = \rho##, the density of the gas at a point with pressure ##P##.

If only we can obtain the variation of pressure with height from the Earth's surface : ##P(x) = ?##, we could use it to find ##\rho(x)##.

This yields ##\frac{m}{V} = \frac{PM}{RT} = \rho##, the density of the gas at a point with pressure ##P##.

If only we can obtain the variation of pressure with height from the Earth's surface : ##P(x) = ?##, we could use it to find ##\rho(x)##.

**Does anyone know?**