Aridity index: Difference between revisions

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#<div class="definition"><div class="short_definition">As used by C. W. Thornthwaite in his 1948 [[climatic classification]]: an index of  the degree of [[water deficit]] below [[water need]] at any given station; a measure of [[aridity]].</div><br/> <div class="paragraph">It is calculated,  independently of the opposite [[humidity index]], as follows:  <div class="display-formula"><blockquote>[[File:ams2001glos-Ae27.gif|link=|center|ams2001glos-Ae27]]</blockquote></div> where ''d'' (the water deficit) is the sum of the monthly differences between precipitation and [[potential  evapotranspiration]] for those months when the [[normal]] precipitation is less than the normal  potential evapotranspiration; and where ''n'' is the sum of monthly values of potential evapotranspiration  for the deficient months.</div><br/> <div class="paragraph">Thornthwaite puts the aridity index to two uses: 1) as a component of the moisture index; 2)  as a basis for the more detailed classification of [[moist climates]] (perhumid, humid, and moist  subhumid climates).</div><br/> </div>
#<div class="definition"><div class="short_definition">As used by C. W. Thornthwaite in his 1948 [[climatic classification]]: an index of  the degree of [[water deficit]] below [[water need]] at any given station; a measure of [[aridity]].</div><br/> <div class="paragraph">It is calculated,  independently of the opposite [[humidity index]], as follows:  <div class="display-formula"><blockquote>[[File:ams2001glos-Ae27.gif|link=|center|ams2001glos-Ae27]]</blockquote></div> where ''d'' (the water deficit) is the sum of the monthly differences between precipitation and [[potential evapotranspiration|potential  evapotranspiration]] for those months when the [[normal]] precipitation is less than the normal  potential evapotranspiration; and where ''n'' is the sum of monthly values of potential evapotranspiration  for the deficient months.</div><br/> <div class="paragraph">Thornthwaite puts the aridity index to two uses: 1) as a component of the moisture index; 2)  as a basis for the more detailed classification of [[moist climates]] (perhumid, humid, and moist  subhumid climates).</div><br/> </div>
#<div class="definition"><div class="short_definition"><br/>''See'' [[index of aridity]].</div><br/> </div>
#<div class="definition"><div class="short_definition"><br/>''See'' [[index of aridity]].</div><br/> </div>
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Revision as of 15:25, 25 April 2012



aridity index[edit | edit source]

  1. As used by C. W. Thornthwaite in his 1948 climatic classification: an index of the degree of water deficit below water need at any given station; a measure of aridity.

    It is calculated, independently of the opposite humidity index, as follows:
    ams2001glos-Ae27
    where d (the water deficit) is the sum of the monthly differences between precipitation and potential evapotranspiration for those months when the normal precipitation is less than the normal potential evapotranspiration; and where n is the sum of monthly values of potential evapotranspiration for the deficient months.

    Thornthwaite puts the aridity index to two uses: 1) as a component of the moisture index; 2) as a basis for the more detailed classification of moist climates (perhumid, humid, and moist subhumid climates).


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