ICAO Standard Atmosphere

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The International Civil Aviation Organization (ICAO) Standard Atmosphere gives the average values for meteorological element at 40°N from mean sea level (MSL) to 80km (262,500 ft).

The ICAO Standard Atmosphere does not contain water vapour

Some of the values defined by ICAO are:

**ICAO Standard Atmosphere**
Height km & ft	Temperature °C	Pressure hPa	Lapse Rate °C/1000ft
0 km MSL	15.0	1013.25	1.98 (Tropospheric)
11 km 36,000 ft	−56.5	226.00	0.00 (Stratospheric)
20 km 65,000 ft	−56.5	54.70	−1.00 (Stratospheric)
32 km 105,000 ft	−44.5	8.68

As this is a Standard, you will never encounter these conditions outside of a laboratory, but many Aviation standards and flying rules are based on this, altimetry being a major one. The standard is very useful in Meteorology for comparing actual values to.