Editing Geopotential height (section)

==Role in planetary fluids==
Geopotential height plays an important role in atmospheric and oceanographic studies.
The differential form above may be substituted into the [[Hydrostatic equilibrium|hydrostatic equation]] and [[ideal gas law]] in order to relate pressure to ambient temperature and geopotential height for measurement by barometric altimeters regardless of latitude or geometric elevation:
:<math>{dP} = {-g}\ {\rho}\ {dZ} = {-g_0}\ {\rho}\ {dH} = \frac{-g_0\ P}{R\ T}\ {dH}</math>
:<math>\frac{dP}{P} = -\frac{g_0}{R\ T}\ {dH}</math>
where <math>P</math> and <math>T</math> are ambient pressure and temperature, respectively, as functions of geopotential height, and <math>R</math> is the specific [[gas constant]]. For the subsequent [[definite integral]], the simplification obtained by assuming a constant value of gravitational acceleration is the sole reason for defining the geopotential altitude.<ref>{{cite book|last=Anderson|first=John|date=2007|title=Introduction to Flight|publisher=McGraw-Hill Science/Engineering/Math|page=116}} </ref>