The Role of Valley Geometry and Energy Budget in the Formation of Nocturnal Valley Winds
Open Access
- 1 June 1989
- journal article
- Published by American Meteorological Society in Journal of Applied Meteorology and Climatology
- Vol. 28 (6) , 445-456
- https://doi.org/10.1175/1520-0450(1989)028<0445:trovga>2.0.co;2
Abstract
Diurnally varying up and down-valley winds are a commonly observed feature of mountain meteorology. These winds are produced through the heating and cooling of the land surface but direct connections from the topography to the winds have been difficult to establish. A concept has been proposed which theoretically relates the energy budget and valley geometry to the rate of atmospheric cooling in the valley. The gradient of the along-valley cooling rate will then lead to an along-valley pressure gradient which provides a topographic control of the wind. The ratio of valley width to cross-section area is shown to be the critical topographic parameter which is proportional to the valley cooling rate. Net radiation and the ground heat flux are also critical to the valley cooling rate. An example is given which illustrates that this new concept can produce pressure gradients about 60% larger than the mountain-plain mechanism. Observations of wind and temperature in three valleys in Colorado which include draining and pooling valleys are consistent with the concept.Keywords
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