Potential Evaporation

Potential evaporation is defined as the amount of water that could be evaporated were it available. It is a function of surface and air temperatures, insolation, and wind, all of which affect water-vapor concentrations immediately above the evaporating surface. The broad definition of a dryland is a place where annual potential evaporation exceeds annual rainfall. In the hot deserts of the Earth, then, potential evaporation is uniformly high. The chart below shows global potential evaporation, with the hot deserts clearly indicated as having very high values. While there is nowhere near enough water available to satisfy potential evaporation in these hot deserts, the parameter can be thought of as a harshness force, a measure of an ecosystem forcing function.

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This site last updated April 8, 1998