Atmospheric boundary layer: Difference between revisions
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<div class="definition"><div class="short_definition">(Abbreviated ABL; <br/>''also called'' boundary layer, planetary boundary layer.) The bottom layer of the [[troposphere]] that is in contact with the surface of the earth.</div><br/> <div class="paragraph">It is often turbulent and is capped by a [[statically stable]] layer of air or [[temperature inversion]]. The ABL depth (i.e., the [[inversion]] height) is variable in time and space, ranging from tens of meters in strongly statically stable situations, to several kilometers in convective conditions over deserts. During [[fair]] weather over land, the ABL has a marked [[diurnal]] cycle. During daytime, a [[mixed layer]] of vigorous [[turbulence]] grows in depth, capped by a statically stable [[entrainment zone]] of intermittent turbulence. Near [[sunset]], turbulence decays, leaving a [[residual layer]] in place of the mixed layer. During nighttime, the bottom of the residual layer is transformed into a statically [[stable boundary layer]] by contact with the radiatively cooled surface. [[Cumulus]] and [[stratocumulus]] clouds can form within the top portion of a humid ABL, while [[fog]] can form at the bottom of a stable boundary layer. The bottom 10% of the ABL is called the [[surface layer]]. <br/>''Compare'' [[Ekman layer]].</div><br/> </div><div class="reference">Stull, R. B. 1988. An Introduction to Boundary Layer Meteorology. 666 pp. </div><br/> | <div class="definition"><div class="short_definition">(Abbreviated ABL; <br/>''also called'' boundary layer, planetary boundary layer.) The bottom layer of the [[troposphere]] that is in contact with the surface of the earth.</div><br/> <div class="paragraph">It is often turbulent and is capped by a [[static stability|statically stable]] layer of air or [[temperature inversion]]. The ABL depth (i.e., the [[inversion]] height) is variable in time and space, ranging from tens of meters in strongly statically stable situations, to several kilometers in convective conditions over deserts. During [[fair]] weather over land, the ABL has a marked [[diurnal]] cycle. During daytime, a [[mixed layer]] of vigorous [[turbulence]] grows in depth, capped by a statically stable [[entrainment zone|entrainment zone]] of intermittent turbulence. Near [[sunset]], turbulence decays, leaving a [[residual layer]] in place of the mixed layer. During nighttime, the bottom of the residual layer is transformed into a statically [[stable boundary layer]] by contact with the radiatively cooled surface. [[cumulus|Cumulus]] and [[stratocumulus]] clouds can form within the top portion of a humid ABL, while [[fog]] can form at the bottom of a stable boundary layer. The bottom 10% of the ABL is called the [[surface layer]]. <br/>''Compare'' [[Ekman layer|Ekman layer]].</div><br/> </div><div class="reference">Stull, R. B. 1988. An Introduction to Boundary Layer Meteorology. 666 pp. </div><br/> | ||
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Revision as of 15:26, 25 April 2012
atmospheric boundary layer[edit | edit source]
(Abbreviated ABL;
also called boundary layer, planetary boundary layer.) The bottom layer of the troposphere that is in contact with the surface of the earth.
also called boundary layer, planetary boundary layer.) The bottom layer of the troposphere that is in contact with the surface of the earth.
It is often turbulent and is capped by a statically stable layer of air or temperature inversion. The ABL depth (i.e., the inversion height) is variable in time and space, ranging from tens of meters in strongly statically stable situations, to several kilometers in convective conditions over deserts. During fair weather over land, the ABL has a marked diurnal cycle. During daytime, a mixed layer of vigorous turbulence grows in depth, capped by a statically stable entrainment zone of intermittent turbulence. Near sunset, turbulence decays, leaving a residual layer in place of the mixed layer. During nighttime, the bottom of the residual layer is transformed into a statically stable boundary layer by contact with the radiatively cooled surface. Cumulus and stratocumulus clouds can form within the top portion of a humid ABL, while fog can form at the bottom of a stable boundary layer. The bottom 10% of the ABL is called the surface layer.
Compare Ekman layer.
Compare Ekman layer.
Stull, R. B. 1988. An Introduction to Boundary Layer Meteorology. 666 pp.
