Standard atmospheric models describe how the properties of air change with altitude. The properties reflect conditions typically expected at that altitude, and do not vary with current climatic conditions. The results are typically used for flight studies, rocketry and ballistics.
This application implements the US Standard Atmosphere model for the lower atmosphere, published by the US Committee on Extension to the Standard Atmosphere (COESA) in 1976.
The model gives the pressure, temperature, density and viscosity of air as a function of geopotential altitude, and is valid from a geopotential altitude of 0 m to 84852 m.
Reference:
US Standard Atmosphere 1976