G-Shock GW-9200BPJ-1 - Manual (Page 84)

E-82
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.
0 m
500 m
1000 m
1500 m
2000 m
2500 m
3000 m
3500 m
4000 m
899 hPa
795 hPa
701 hPa
616 hPa
8.5 °C
2 °C
–4.5 °C
–11 °C
15 °C 1013 hPa
About 6.5 °C
per 1000 m
About 8 hPa per 100 m
About 9 hPa per 100 m
About 10 hPa per 100 m
About 11 hPa per 100 m
About 12 hPa per 100 m
Altitude Air Pressure Temperature
Source: International Civil Aviation Organization