Sections :

International Standard Atmosphere (ISA)

Sea Level Conditions

ISA Variation with Altitude

Variation due to Local Ground Conditions

Variation of Density due to Humidity

Variation of Density with Extremely High Altitude

Tabulated Data :

Table of Atmosphere Properties.

Software :

Atmosphere Properties Web Calculator

Atmosphere Properties Calculator (MS Windows Executable)


The formula in the previous sections and the tabulated data below give accurate predictions for an ideal atmosphere in the lower portions near the earth's surface, the troposphere and the lower stratosphere. This covers the first 20km which is where almost all aviation takes place. For variations in density beyond this level to the edge of space, where continuous gas behaviour no longer applies, a rough approximation can be used by assuming there is a logarithmic decay from sea level to the edge of space.


where $h$ is the altitude in kilometers.


High Altitude Density Approximation

While this estimate is rather crude for small changes over the atmosphere near the earth's surface, it is a simple way to estimate density effects for drag on launch vehicles that will rapidly go from surface to orbital altitudes of 200 to 300km or more.