Orographic cloud

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orographic cloud

Mountain clouds produced by orographic lifting of moist air to saturation.

Clouds formed by upslope winds are generally stratiform, those formed by mountain wave updrafts are often lenticularis-type or wave clouds, and those formed by heating, such as elevated heat source or leeside convergence effects, are generally cumuliform. Upslope and wave clouds are clouds with form and extent determined by the disturbing effects of orography upon the passing flow of air. Because these clouds are linked to the topography, they are generally standing clouds, even though the winds at the same level may be very strong. Orographic upslope clouds include stratiform cap or crest clouds and the foehn wall. Convective orographic clouds are also strongly tied to the topography. Banta (1990) finds that mountain flows, which are driven by the topography interacting with the large-scale winds and the diurnal heating cycle, "play a significant role in determining where convective cells will initiate, and often how precipitation from the showers will be distributed spatially . . . they regulate not only the location of storm initiations, but also the timing."

Banta, R. M. 1990. The role of mountain flows in making clouds. Meteor. Monogr.. 45. p. 283.

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