Geopotential is the potential energy acquired by unit mass on being raised through unit distance in a field of gravitational force of unit strength. The Geopotential meter is related to the Dynamic meter by the expression one geopotential meter=0.98 dynamic meter. It is roughly the height of a pressure surface in the atmosphere above mean sea level.
The equation which defines the relationship between geopotential height (Z) and geometric height (z) is Z=gz/980. Thus when gravity g has its near average value of 980 cm/sec2, heights in geopotential meters and and geometric meters are the same; for g < 980 cm/sec2 the height in geopotential meters is the smaller, for g > 980 cm/sec2 it is bigger.
Geopotential (from the dynamic point of view) is a better measure of height in the atmosphere than is geometric height since energy is in general lost or gained when air moves along a geometrically level surface but not when it moves along an equigeopotential surface.