Lee trough: Difference between revisions

Latest revision as of 17:19, 25 April 2012

lee trough

(Same as dynamic trough.) A pressure trough formed on the lee side of a mountain range in situations where the wind is blowing with a substantial component across the mountain ridge; often seen on United States weather maps east of the Rocky Mountains, and sometimes east of the Appalachians, where it is less pronounced.

Its formation may be explained thermodynamically by the warming due to adiabatic compression of the sinking air on the lee side of the mountain range, or dynamically by generation of cyclonic circulation (cyclogenesis) by the horizontal convergence associated with vertical stretching of air columns passing over the ridge and descending the lee slope. Alternatively, the latter viewpoint is often expressed as the conservation of potential vorticity, where the vertical stretching of the columns is compensated by an increase in their relative vorticity.
See lee cyclogenesis.

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-<div class="definition"><div class="short_definition">(<br/>''Same as'' dynamic trough.) A pressure [[trough]] formed on the lee side of a mountain  range in situations where the [[wind]] is blowing with a substantial component across the mountain  ridge; often seen on United States weather maps east of the Rocky Mountains, and sometimes east  of the Appalachians, where it is less pronounced.</div><br/> <div class="paragraph">Its formation may be explained thermodynamically by the warming due to [[adiabatic]] compression  of the sinking air on the lee side of the mountain range, or dynamically by generation of [[cyclonic  circulation]] ([[cyclogenesis]]) by the horizontal [[convergence]] associated with [[vertical stretching]] of  air columns passing over the ridge and descending the lee slope. Alternatively, the latter viewpoint  is often expressed as the conservation of [[potential vorticity]], where the vertical stretching of the  columns is compensated by an increase in their [[relative vorticity]]. <br/>''See'' [[lee cyclogenesis]].</div><br/> </div>
+<div class="definition"><div class="short_definition">(''Same as'' dynamic trough.) A pressure [[trough]] formed on the lee side of a mountain  range in situations where the [[wind]] is blowing with a substantial component across the mountain  ridge; often seen on United States weather maps east of the Rocky Mountains, and sometimes east  of the Appalachians, where it is less pronounced.</div><br/> <div class="paragraph">Its formation may be explained thermodynamically by the warming due to [[adiabatic]] compression  of the sinking air on the lee side of the mountain range, or dynamically by generation of [[cyclonic circulation|cyclonic  circulation]] ([[cyclogenesis]]) by the horizontal [[convergence]] associated with [[vertical stretching]] of  air columns passing over the ridge and descending the lee slope. Alternatively, the latter viewpoint  is often expressed as the conservation of [[potential vorticity]], where the vertical stretching of the  columns is compensated by an increase in their [[relative vorticity]]. <br/>''See'' [[lee cyclogenesis]].</div><br/> </div>
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