Casio 3069 Question: How does the altimeter work

Question: How does the altimeter work?

Answer: Generally, air pressure and temperature decrease as altitude increases. This watch bases its altitude measurements on International Standard Atmosphere (ISA) values stipulated by the International Civil Aviation Organization (ICAO). These values define relationships between altitude, air pressure, and temperature.

Altitude		Air Pressure		Temperature
4000 m	616 hPa		About 8 hPa per 100 m	–11°C
3500 m	701 hPa			–4.5°C
3000 m			About 9 hPa per 100 m		About 6.5°C
2500 m
	795 hPa			2°C	per 1000 m
2000 m			About 10 hPa per 100 m
1500 m	899 hPa		About 11 hPa per 100 m	8.5°C
1000 m
500 m	1013 hPa		About 12 hPa per 100 m	15°C
0 m

Source: International Civil Aviation Organization

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