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Fog - Causes And Types Of Fog, Radiation Fogs, Advection Fogs, Evaporation Fogs - Precipitation fog

atmospheric earth fronts air

Fog is caused by the condensation of water at or near Earth's surface. The atmosphere is obscured—essentially by cloud formation—near the surface and fog conditions are generally characterized as existing when atmospheric visibility is reduced to about one-half mile (approximately 0.8 km).

Precipitation fog is a type of evaporation fog that happens when relatively warm rain or snow falls through cool, almost saturated air, and evaporation from the precipitation saturates the cool air. It can turn dense, persist for a long time, and may extend over large areas. Although usually associated with warm fronts, precipitation fog also occurs with slow moving fronts or stationary fronts to form frontal fogs.



Hamblin, W. K., and E. H. Christiansen. Earth's Dynamic Systems. 9th ed. Upper Saddle River: Prentice Hall, 2001.

Hancock, P. L., and B. J. Skinner, eds. The Oxford Companion to the Earth. New York: Oxford University Press, 2000.

Keller, E. A. Introduction to Environmental Geology. 2nd ed. Upper Saddle River: Prentice Hall, 2002.

Agnes Galambosi


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Dew point

—The temperature at which water vapor in the air condenses to form liquid water droplets.

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