Geopotential Altitude
Gravitational acceleration, g(z), decreases with altitude since moving up means moving away from the planet's center.
This problem of decreasing g can be dealt with by defining a transformation from real geometric altitude z to an abstraction called "geopotential altitude" h, defined:
h has the property
- where
Which basically says the amount of work done lifting a test mass m to height z through an atmosphere where gravity decreases with altitude, is the same as the amount of work done lifting that same mass to a height h through an atmosphere where g magically remains equal to g0, its value at sea level.
This geopotential altitude h is then used instead of geometric altitude z in the hydrostatic equations.
Read more about this topic: Atmospheric Models
Famous quotes containing the word altitude:
“On a level plain, simple mounds look like hills; and the insipid flatness of our present bourgeoisie is to be measured by the altitude of its “great intellects.””
—Karl Marx (1818–1883)