Köppen climate classification: Difference between revisions

== {{anchor|B}}Group B: Dry (desert and semi-arid) climates ==

[[File:Koppen-Geiger Map B present.svg|thumb|400px|right|Dry climate distribution]]

These climates are characterized by the amount of annual precipitation less than a threshold value which approximates the [[potential evapotranspiration]].<ref name=McKnight />{{rp|212}} The threshold value (in millimeters) is calculated as follows:

Multiply the average annual temperature in °C by 20, then add

:(a) 280 if 70% or more of the total precipitation is in the high-sun half of the year (April through September in the Northern Hemisphere, or October through March in the Southern), or

:(b) 140 if 30%–70% of the total precipitation is received during the applicable period, or

:(c) 0 if less than 30% of the total precipitation is so received.

According to the modified Köppen classification system used by modern climatologists, total precipitation in the warmest six months of the year is taken as reference instead of the total precipitation in the high-sun half of the year.<ref>{{cite web|url=http://snow.cals.uidaho.edu/Clim_Map/koppen_criteria.htm |author=Critchfield, H.J. |year=1983 |edition=4 |title=Criteria for classification of major climatic types in modified Köppen system |publisher=University of Idaho |url-status=bot: unknown |archive-url=https://web.archive.org/web/20090930221104/http://snow.cals.uidaho.edu/Clim_Map/koppen_criteria.htm |archive-date=2009-09-30 }}</ref>

A third letter can be included to indicate temperature. Originally, ''h'' signified low-latitude climate (average annual temperature above 18&nbsp;°C) while ''k'' signified middle-latitude climate (average annual temperature below 18&nbsp;°C), but the more common practice today, especially in the United States, is to use ''h'' to mean the coldest month has an average temperature above 0&nbsp;°C (32&nbsp;°F) (or {{convert|-3|°C|°F|0}}), with ''k'' denoting that at least one month averages below 0&nbsp;°C.

Desert areas situated along the west coasts of continents at tropical or near-tropical locations characterized by [[Fog desert|frequent fog]] and low clouds, despite the fact that these places rank among the driest on earth in terms of actual precipitation received are labelled ''BWn'' with the n denoting a climate characterized by frequent fog.<ref name=Cereceda>{{cite journal |last1=Cereceda |first1=P. |last2=Larrain |first2=H. |last3=osses |first3=P. |last4=Farias |first4=M. |last5=Egaña |first5=I. |year=2008 |title=The climate of the coast and fog zone in the Tarapacá Region, Atacama Desert, Chile |journal=Atmospheric Research |volume=87 |issue=3–4 |pages=301–311 |doi=10.1016/j.atmosres.2007.11.011 |bibcode=2008AtmRe..87..301C|hdl=10533/139314 |hdl-access=free }}</ref><ref name=gepchile /><ref name=Inzunza /> The ''BSn'' category can be found in foggy coastal steppes.<ref>{{cite web |url=http://www.agrimed.cl/atlas/tomo1.html |title=Atlas Agroclimático de Chile–Estado Actual y Tendencias del Clima (Tomo I: Regiones de Arica Y Parinacota, Tarapacá y Antofagasta |publisher=Universidad de Chile |language=es |year=2017 |access-date=9 December 2018 |archive-url=https://web.archive.org/web/20181222105247/http://www.agrimed.cl/atlas/tomo1.html |archive-date=22 December 2018 |url-status=live }}</ref>

=== {{anchor|BW}}''BW'': Arid climate ===

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* [[Coober Pedy]], [[Australia]] (''BWh'')

* [[Bakersfield, California]], United States (''BWh'')

* [[Upington]], [[Northern Cape]] [[South Africa]] (''BWh'')

* [[Phoenix, Arizona|Phoenix]], [[Arizona]], United States (''BWh'')

* [[Las Vegas]], [[Nevada]], United States (''BWh'')

* [[Death Valley]], [[California]], [[United States]] (''BWh''), location of the hottest air temperature ever recorded on Earth.

* [[‘Aziziya]], [[Jafara]], [[Libya]] (''BWh'')

* [[Karachi, Pakistan]] (''BWh'')

* [[Doha, Qatar]] (''BWh'')

* [[Riyadh]], [[Saudi Arabia]] (''BWh'')

* [[Muscat, Oman]] (''BWh'')

* [[Cairo]], [[Egypt]] (''BWh'')

* [[Djibouti City]], [[Djibouti]] (''BWh'')

* [[Lima]], [[Peru]] (''BWh'')

* [[El Paso, Texas]], [[United States]] (''BWk'', bordering on ''BWh'')

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