Difference between revisions of "Adiabatic lapse rate"

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== adiabatic lapse rate ==
 
== adiabatic lapse rate ==
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<div class="definition"><div class="short_definition">In most contexts, <br/>''same as'' [[dry-adiabatic lapse rate]].</div><br/> <div class="paragraph"><br/>''See also'' [[saturation-adiabatic lapse rate]].</div><br/> </div>
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<div class="definition"><div class="short_definition">The rate of decrease in [[temperature]] with height via an [[adiabatic process]].</div><br/> </div>
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#<div class="definition"><div class="short_definition">Dry-adiabatic lapse rate</div> <div class="paragraph">A [[process lapse rate]] of temperature, the rate of decrease of temperature with height of a [[parcel]] of [[dry air]] lifted by a reversible adiabatic process through an [[atmosphere]] in [[hydrostatic equilibrium]].</div> <div class="paragraph">This lapse rate is ''g''/''c''<sub>''pd''</sub>, where ''g'' is the gravitational [[acceleration]] and ''c''<sub>''pd''</sub> is the [[specific heat]] of dry air at constant [[pressure]], approximately 9.8&#x000b0;C km<sup>&#8722;1</sup>. [[Potential temperature]] is constant with height in an [[atmospheric layer]] with this lapse rate.</div><br/>
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#<div class="definition"><div class="short_definition">Moist-unsaturated adiabatic lapse rate</div> <div class="paragraph">The adiabatic lapse rate of unsaturated air containing [[water vapor]].</div> <div class="paragraph">This differs from definition 1 by the factor <div class="display-formula"><blockquote>[[File:ams2001glos-De50.gif|link=|center|ams2001glos-De50]]</blockquote></div> where ''r''<sub>''&#965;''</sub> is the [[mixing ratio]] of water vapor and ''c''<sub>''p&#965;''</sub> is the specific heat of water vapor.</div><br/>
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#<div class="definition"><div class="short_definition">Moist-adiabatic lapse rate (or saturation-adiabatic lapse rate or moist-saturated adiabatic lapse rate)</div> <div class="paragraph">The rate of decrease of temperature with height along a [[moist adiabat]].</div> <div class="paragraph">It is given approximately by &#915;<sub>''m''</sub> in the following: <div class="display-formula"><blockquote>[[File:ams2001glos-Me16.gif|link=|center|ams2001glos-Me16]]</blockquote></div> where ''g'' is the gravitational  acceleration, ''c''<sub>''pd''</sub> is the  specific heat at constant pressure of dry air, ''r''<sub>''&#965;''</sub> is the mixing ratio of water vapor, ''L''<sub>''&#965;''</sub> is the  [[latent heat]] of [[vaporization]], ''R'' is the [[gas constant]] for dry air, ''&#949;'' is the ratio of the gas constants for dry air and water vapor, and ''T'' is temperature. This expression is an approximation for both the [[reversible moist-adiabatic process|reversible moist-adiabatic]] lapse rate and the [[pseudoadiabatic lapse rate]], with more accurate expressions given under those definitions. When most of the condensed water is frozen, this may be replaced by a similar expression but with ''L''<sub>''&#965;''</sub> replaced by the latent heat of [[sublimation]].</div><br/>
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<p>''Term edited 17 June 2021.''</p>
  
 
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Revision as of 12:31, 17 June 2021



adiabatic lapse rate

The rate of decrease in temperature with height via an adiabatic process.

  1. Dry-adiabatic lapse rate
    A process lapse rate of temperature, the rate of decrease of temperature with height of a parcel of dry air lifted by a reversible adiabatic process through an atmosphere in hydrostatic equilibrium.
    This lapse rate is g/cpd, where g is the gravitational acceleration and cpd is the specific heat of dry air at constant pressure, approximately 9.8°C km−1. Potential temperature is constant with height in an atmospheric layer with this lapse rate.

  2. Moist-unsaturated adiabatic lapse rate
    The adiabatic lapse rate of unsaturated air containing water vapor.
    This differs from definition 1 by the factor
    ams2001glos-De50
    where rυ is the mixing ratio of water vapor and c is the specific heat of water vapor.

  3. Moist-adiabatic lapse rate (or saturation-adiabatic lapse rate or moist-saturated adiabatic lapse rate)
    The rate of decrease of temperature with height along a moist adiabat.
    It is given approximately by Γm in the following:
    ams2001glos-Me16
    where g is the gravitational  acceleration, cpd is the  specific heat at constant pressure of dry air, rυ is the mixing ratio of water vapor, Lυ is the  latent heat of vaporizationR is the gas constant for dry air, ε is the ratio of the gas constants for dry air and water vapor, and T is temperature. This expression is an approximation for both the reversible moist-adiabatic lapse rate and the pseudoadiabatic lapse rate, with more accurate expressions given under those definitions. When most of the condensed water is frozen, this may be replaced by a similar expression but with Lυ replaced by the latent heat of sublimation.

Term edited 17 June 2021.