Atmospheric air
Moist Air. Basics and measurement

According to the International Civil Aviation Organization (ICAO), typical dry air is defined on the following basis:

• air is considered a perfect gas;

• it is free of water vapour;

• the physical constants are as follows :

  • molar mass M _a: 28.96455 · 10^–3 kg · mol^–1,

  • atmospheric pressure at sea level: 101,325 Pa,

  • temperature at sea level: 15°C,

  • density at sea level: 1.226 kg · m^–3,

  • universal perfect gas constant: 8.3143 J · mol^–1· K^–1,

  • molar composition given in table 1.