ICAO Standard Atmosphere
The International Civil Aviation Organization (ICAO) published their "ICAO Standard Atmosphere" as Doc 7488-CD in 1993. It has the same model as the ISA, but extends the altitude coverage to 80 kilometres (262,500 feet).
The ICAO Standard Atmosphere does not contain water vapour
Some of the values defined by ICAO are:
| Height km & ft | Temperature °C | Pressure hPa | Lapse Rate °C/1000 ft |
|---|---|---|---|
| 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 | +0.3 (Stratospheric) |
| 32 km 105 000 ft | −44.5 | 8.68 |
As this is a Standard, you will not always 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 against actual values.
Read more about this topic: International Standard Atmosphere
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