Dynamic Height

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Dynamic Height

The height of a point in the atmosphere expressed in a unit proportional to the geopotential at that point. Since the geopotential at altitude z is numerically equal to the work done when a particle of unit mass is lifted from sea level up to this height, the dimensions of dynamic height are those of potential energy per unit mass. Also called geodynamic height. </dd>
The standard unit of dynamic height Hd is the dynamic meter (or geodynamic meter), defined as 10 meters per second squared; it is related to the geopotential Missing Image:img src="SP7-d_files/phisms.gif", the geometric height z in meters, and the geopotential height Z in geopotential meters by

''dMissing Image:img src="SP7-d_files/phisms.gif"= 10d Hd = 9.8dZ = gdz''
where g is the acceleration of gravity in meters per second

squared. (Some sources prefer to give the constants 10 and 9.8 the units of meters per second squared so that the units of Missing Image:img src="SP7-d_files/phisms.gif" and Z would be the same as those of the geometric height.) The dynamic meter is about 2 percent longer than the geometric meter and the geopotential meter. One of the practical advantages of the dynamic height over the geometric height is that when the former is introduced into the hydrostatic equation the variable acceleration of gravity is eliminated. In meteorological height calculations, geopotential height is more often used than dynamic height. </dd>


This article is based on NASA's Dictionary of Technical Terms for Aerospace Use