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{{legend|#FE9695|[[#Cold desert climates|BWk]] (cold desert climates)}}]]
The '''desert climate''' or '''arid climate''' (in the [[Köppen climate classification]] ''BWh'' and ''BWk'') is a [[dry climate]] sub-type in which there is a severe excess of [[evaporation]] over [[precipitation]]. The typically bald, rocky, or sandy surfaces in desert climates are dry and hold little moisture, quickly evaporating the already little rainfall they receive. Covering 14.2% of Earth's land area, hot deserts are the second most common type of climate on Earth after the [[polar climate]].<ref name="peel et al">{{cite journal |last=Peel |first=M. C. |author2=B. L. Finlayson |author3=T. A. McMahon |year=2007 |title=Updated world map of the Köppen-Geiger climate classification |url=https://www.hydrol-earth-syst-sci.net/11/1633/2007/hess-11-1633-2007.pdf
There are two variations of a [[desert]] climate according to the [[Köppen climate classification]]: a hot desert climate (''BWh''), and a cold desert climate (''BWk''). To delineate "hot desert climates" from "cold desert climates", a mean annual temperature of {{cvt|18|C|1}} is used as an isotherm so that a location with a ''BW'' type climate with the appropriate temperature above this isotherm is classified as "hot arid subtype" (''BW'''h'''''), and a location with the appropriate temperature below the isotherm is classified as "cold arid subtype" (''BW'''k''''').
Most desert/arid climates receive between {{cvt|25|and|200|mm|0}} of rainfall annually,<ref>{{cite book |title=Deserts and Desert Environments |first=Julie J. |last=Laity |publisher=John Wiley & Sons |year=2009 |page=7 |url=https://books.google.com/books?id=wtAbzLLTcwcC&pg=PR5 |isbn=978-1444300741 }}</ref><ref>{{Cite web |date=2017-11-01 |title=What is a Desert Climate? |url=https://www.worldatlas.com/articles/what-is-a-desert-climate.html |access-date=2022-04-23 |website=WorldAtlas |language=en-US}}</ref> although some of the most consistently hot areas of [[Central Australia]], the [[Sahel]] and [[Guajira Peninsula]] can be, due to extreme [[potential evapotranspiration]], classed as arid with the annual rainfall as high as {{convert|430|mm|in|0|disp=or}}.
{{See also|Aridity index}}
==Precipitation==
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==Hot desert climates==
{{redirect|BWh|other uses|Bwh (disambiguation)}}
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|source=[http://www.worldweatheronline.com/Sabhah-weather-averages/Sabha/LY.aspx World Weather Online]
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Hot desert climates (''BWh'') are typically found under the [[subtropical ridge]] in the lower middle latitudes or the [[subtropics]], often between 20° and 33° north and south latitudes. In these locations, stable descending air and high pressure aloft clear clouds and create hot, arid conditions with intense sunshine. Hot desert climates are found across vast areas of [[North Africa]], [[
At the time of high sun (summer), scorching, desiccating heat prevails. Hot-month average temperatures are normally between {{cvt|29|and|35|C}}, and midday readings of {{convert|43–46|C|F}} are common. The world absolute heat records, over {{convert|50|C|F}}, are generally in the hot deserts, where the heat potential can be the highest on the planet. This includes the record of {{convert|56.7|C|F}} in [[Death Valley]], which is currently considered the [[highest temperature recorded on Earth]].<ref>{{Cite web |last1=Valley |first1=Mailing Address: P. O. Box 579 Death |last2=Us |first2=CA 92328 Phone: 760 786-3200 Contact |title=Weather - Death Valley National Park (U.S. National Park Service) |url=https://www.nps.gov/deva/learn/nature/weather-and-climate.htm |access-date=2022-04-23 |website=www.nps.gov |language=en}}</ref> Some deserts in the [[tropics]] consistently experience very high temperatures all year long, even during wintertime. These locations feature some of the highest annual average temperatures recorded on Earth, exceeding {{convert|30|C|F}}, up to nearly {{convert|35|C|F}} in [[Dallol, Ethiopia]]. This last feature is seen in sections of Africa and [[Arabia]]. During colder periods of the year, night-time temperatures can drop to freezing or below due to the exceptional radiation loss under the clear skies. However, very rarely do temperatures drop far below freezing under the hot subtype.
[[File:Koppen-
Hot desert climates can be found in the deserts of [[North Africa]] such as the wide [[Sahara Desert]], the [[Libyan Desert]] or the [[Nubian Desert]]; deserts of the [[Horn of Africa]] such as the [[Danakil Desert]] or the [[Grand Bara|Grand Bara Desert]]; deserts of [[Southern Africa]] such as the [[Namib Desert]] or the [[Kalahari Desert]]; deserts of [[
[[File:Desierto del Sahara.jpg|thumb|Sahara Desert in Morocco.]]
Hot deserts are lands of extremes: most of them are among the hottest, the driest and the sunniest places on Earth because of nearly constant high pressure; the nearly permanent removal of low-pressure systems, dynamic fronts and atmospheric disturbances; sinking air motion; dry atmosphere near the surface and aloft; the exacerbated exposure to the sun where solar angles are always high makes this desert inhospitable to most species. ==Cold desert climates==
{{Redirect|BWk||BWK (disambiguation){{!}}BWK}}
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[[File:Koppen-
Cold desert climates (''BWk'') usually feature hot (or warm in a few instances), dry summers, though summers are not typically as hot as hot desert climates. Unlike hot desert climates, cold desert climates tend to feature cold, dry winters. Snow tends to be rare in regions with this climate. The [[Gobi Desert]] in northern China and Mongolia is one example of cold desert. Though hot in the summer, it shares the very cold winters of the rest of [[Inner Asia]]. Summers in South America's [[Atacama Desert]] are mild with only slight temperature variations between seasons. Cold desert climates are typically found at higher altitudes than hot desert climates and are usually drier than hot desert climates.
[[File:Atacama Desert between Antofagasta and Taltal.jpg|thumb|Atacama Desert in Chile.]]
[[File:Gobi, krajobraz pustyni (25).jpg|thumb|Gobi Desert in Mongolia]]
Cold desert climates are typically located in temperate zones in the 30s and 40s latitudes, usually in the leeward [[rain shadow]] of high mountains, which restricts precipitation from the westerly winds. An example of this is the [[Patagonian Desert]] in Argentina bounded by the [[Andes|Andes ranges]] to its west. In the case of Central Asia, mountains restrict precipitation from the [[East Asian monsoon|eastern monsoon]]. The [[Kyzyl Kum]], [[Taklamakan Desert|Taklamakan]] and [[Cold Desert, Skardu|Katpana Desert]] deserts of [[Central Asia]] are other major examples of ''BWk'' climates. The [[Ladakh]] region, and the city of [[Leh]] in the [[Great Himalayas]] in India also have a cold desert climate. In North America, the cold desert climate occurs in the drier parts of the [[Great Basin Desert]] and the [[Bighorn Basin]] in [[Big Horn County, Wyoming|Big Horn]] and [[Washakie County, Wyoming|Washakie County]] in [[list of counties in Wyoming|Wyoming]]. The [[Hautes Plaines]], located in the northeastern section of [[Morocco]] and in [[Algeria]] is another major example of a cold desert climate. In [[Europe]], this climate can only be found in some inland parts of southeastern Spain, such as in [[Lorca, Spain|Lorca]].<ref>{{Cite web |last=Meteorología |first=Agencia Estatal de |title=Valores climatológicos normales - Agencia Estatal de Meteorología - AEMET. Gobierno de España |url=https://www.aemet.es/es/serviciosclimaticos/datosclimatologicos/valoresclimatologicos |access-date=2024-01-08 |website=www.aemet.es |language=es}}</ref><ref>{{Cite web |title=Evolucion de los climas de Koppen en España: 1951-2020 |url=https://www.aemet.es/documentos/es/conocermas/recursos_en_linea/publicaciones_y_estudios/publicaciones/NT_37_AEMET/NT_37_AEMET.pdf |access-date=2024-01-08 |website=[[Agencia Estatal de Meteorologia]]}}</ref>
Arctic and Antarctic regions also receive very little precipitation during the year, owing to the exceptionally cold dry air freezing most precipitation; however, both of them are generally classified as having [[polar climate]]s because they have average summer temperatures below {{convert|10|°C|0}} even if they have such desert-like features as intermittent streams, hypersaline lakes, and extremely barren terrain in unglaciated areas such as the [[McMurdo Dry Valleys]] of Antarctica.<ref>{{Cite web | url=https://sand-boarding.com/cold-deserts/ |title = Cold and Polar Deserts| date=3 January 2022 |access-date=2022-03-03}}</ref><ref>{{Cite web |title=Why are polar regions not considered deserts? – SidmartinBio |url=https://www.sidmartinbio.org/why-are-polar-regions-not-considered-deserts/ |access-date=2022-04-23 |website=www.sidmartinbio.org}}</ref>
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