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{{short description|Arid climate subtype in the Köppen climate classification system with very little precipitation}}
{{use dmy dates|date=September 2024}}
[[File:BW climate.png|thumb|right|upright=1.6|Regions with desert climates
{{legend|#FE0000|[[#Hot desert climates|BWh]] (hot desert climates)}}
{{legend|#FE9695|[[#Cold desert climates|
The '''desert climate''' or '''arid climate''' (in the [[Köppen climate classification]] ''BWh'' and ''
There are two variations of a [[desert]] climate according to the [[Köppen climate classification]]: a hot desert climate (''BWh''), and a cold desert climate (''
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 |archive-date=2021-12-26 |archive-url=https://web.archive.org/web/20211226192324/https://www.worldatlas.com/articles/what-is-a-desert-climate.html |url-status=live }}</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==
Although no part of Earth is known for certain to be rainless, in the [[Atacama Desert]] of northern Chile, the average annual rainfall over 17 years was only
To determine whether a location has an arid climate, the precipitation threshold is determined. The precipitation threshold (in millimetres) involves first multiplying the average annual temperature in °C by 20, then adding 280 if 70% or more of the total precipitation is in the high-sun summer half of the year (April through September in the [[Northern Hemisphere]], or October through March in the Southern), or 140 if 30–70% of the total precipitation is received during the applicable period, or 0 if less than 30% of the total precipitation is so received there. If the area's annual precipitation is less than half the threshold (50%), it is classified as a ''BW'' (desert climate), while 50–100% of the threshold results in a [[Semi-arid climate|semi-arid]] climate.<ref
==Hot desert climates==
{{redirect|BWh|other uses|Bwh (disambiguation)}}
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]], [[West Asia]], northwestern parts of the [[Indian Subcontinent]], southwestern Africa, interior Australia, the [[Southwestern United States]], northern [[Mexico]], sections of southeastern [[Spain]], the coast of [[Peru]], and [[Chile]]. This makes hot deserts present in every continent except Antarctica.
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 |title=Weather - Death Valley National Park |website=U.S. National Park Service |url=https://www.nps.gov/deva/learn/nature/weather-and-climate.htm |access-date=2022-04-23 |language=en |archive-date=2020-10-13 |archive-url=https://web.archive.org/web/20201013021511/https://www.nps.gov/deva/learn/nature/weather-and-climate.htm |url-status=live }}</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-Geiger_Map_v2_BWh_1991–2020.svg|thumb|left|250px|Regions with hot desert climates]]
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 [[West Asia]] such as the [[Arabian Desert]], or the [[Syrian Desert]]; deserts of [[South Asia]] such as [[Dasht-e Lut]] and [[Dasht-e Kavir]] of Iran or the [[Thar Desert]] of India and Pakistan; deserts of the United States and Mexico such as the [[Mojave Desert]], the [[Sonoran Desert]] or the [[Chihuahuan Desert]]; deserts of Australia such as the [[Simpson Desert]] or the [[Great Victoria Desert]] and many other regions. In [[Europe]], the hot desert climate can only be found on southeastern coast of [[Spain]] as well as small inland parts of southeastern, especially parts of the [[Tabernas Desert]].<ref>{{cite book |title=Atlas Climático Ibérico |trans-title=Iberian Climate Atlas |year=2011 |url=http://www.aemet.es/documentos/es/conocermas/recursos_en_linea/publicaciones_y_estudios/publicaciones/Atlas-climatologico/Atlas.pdf |doi=10.31978/784-11-002-5 |isbn=978-84-7837-079-5 |lang=es, pt, en |access-date=May 8, 2017|archive-date=November 25, 2020|archive-url=https://web.archive.org/web/20201125004016/http://www.aemet.es/documentos/es/conocermas/recursos_en_linea/publicaciones_y_estudios/publicaciones/Atlas-climatologico/Atlas.pdf|url-status=live}}</ref><ref name="ChazzaraBernabé_2022">{{Cite report |year=2022 |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]] |archive-date=2024-02-13 |archive-url=https://web.archive.org/web/20240213184548/https://www.aemet.es/documentos/es/conocermas/recursos_en_linea/publicaciones_y_estudios/publicaciones/NT_37_AEMET/NT_37_AEMET.pdf |url-status=live |lang=es |first1=Andrés |last1=Chazarra Bernabé |first2=Belinda |last2=Lorenzo Mariño |first3=Ramiro |last3=Romero Fresneda |first4=José Vicente |last4=Moreno García |series=Nota técnica de AEMET |volume=37 |doi=10.31978/666-22-011-4}}</ref>
[[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}}
[[File:Koppen-Geiger_Map_v2_BWk_1991–2020.svg|thumb|left|Regions with cold desert climates]]
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 |title=Valores climatológicos normales |website=Agencia Estatal de Meteorología |url=https://www.aemet.es/es/serviciosclimaticos/datosclimatologicos/valoresclimatologicos |access-date=2024-01-08 |language=es |archive-date=2023-03-26 |archive-url=https://web.archive.org/web/20230326032223/https://www.aemet.es/es/serviciosclimaticos/datosclimatologicos/valoresclimatologicos |url-status=live }}</ref><ref name="ChazzaraBernabé_2022"/>
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 deserts: what they are and where can you find them | date=3 January 2022 | access-date=2022-03-03 | archive-date=2024-09-10 | archive-url=https://web.archive.org/web/20240910142007/https://sand-boarding.com/cold-deserts/ | url-status=live }}{{better source needed|date=September 2024}}</ref>
== Climate charts ==
{{climate chart|[[Sabha, Libya|Sabha]], [[Libya]]
|6|19|7
|8|21|0
Line 30 ⟶ 54:
|12|26|1
|7|20|1
|float=
|clear=
|source=[http://www.worldweatheronline.com/Sabhah-weather-averages/Sabha/LY.aspx World Weather Online]
}}
{{climate chart|[[Karachi]], [[Pakistan]] (bordering on [[semi arid]])
|12.0|26.3|10.6
|14.8|28.7|5.5
|19.4|32.6|3.2
|23.7|35.0|21.1
|27.0|35.7|26.2
|28.6|35.7|44.6
|27.9|33.6|73.1
|26.7|32.5|104.7
|26.0|33.4|44.0
|22.9|35.6|12.7
|17.7|32.6|0.7
|13.4|28.4|5.6
|float=left
|clear=none
|source=[[NOAA]]<ref>{{cite web |url=https://www.nodc.noaa.gov/archive/arc0216/0253808/2.2/data/0-data/Region-2-WMO-Normals-9120/Pakistan/CSV/Karachi_41780.csv |title=Karachi Climate Normals 1991–2020 |work=World Meteorological Organization Climatological Standard Normals (1991–2020) |publisher=National Oceanic and Atmospheric Administration |access-date=17 September 2023 |archive-date=10 September 2024 |archive-url=https://web.archive.org/web/20240910142006/https://www.nodc.noaa.gov/archive/arc0216/0253808/2.2/data/0-data/Region-2-WMO-Normals-9120/Pakistan/CSV/Karachi_41780.csv |url-status=live }}</ref>}}
{{climate chart|[[Las Vegas]], [[Nevada]], [[United States]]
|
|6.7
|10.
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|
|
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|22.4|34.9|8.1
|15.3|27.3|8.1
|8.5|19.5|7.6
|4.2|13.8|11
|float=left
|clear=right
|source=[[NOAA]]<ref name = "NOWData NWS Las Vegas, NV (VEF) - LASthr">{{cite web
|url = https://w2.weather.gov/climate/xmacis.php?wfo=vef
|title = NowData – NOAA Online Weather Data
|publisher = [[National Oceanic and Atmospheric Administration]]
|access-date = October 11, 2021
|archive-date = July 21, 2021
|archive-url = https://web.archive.org/web/20210721064827/https://w2.weather.gov/climate/xmacis.php?wfo=vef
|url-status = dead
}}</ref>}}
{{climate chart|[[Leh]], [[India]]
|-13.1|1.5|4.3
|-9.2|4.2|2.5
|-3.7|9.7|1.5
|1.6|15.3|1.7
|6.2|20.0|0.6
|11.3|24.4|2.9
|15.9|28.5|6.8
|15.1|28.1|6.2
|9.2|23.4|4.4
|0.3|16.7|2.3
|-7.2|10.6|0.7
|-11.7|4.5|1.0
|float=left
|clear=left
|units=metric
|source= <ref>{{Cite web |url=http://www.imd.gov.in/section/climate/extreme/leh2.htm |title=Leh |access-date=2017-08-16 |archive-url=https://web.archive.org/web/20180225132218/http://www.imd.gov.in/section/climate/extreme/leh2.htm |archive-date=2018-02-25 |url-status=dead |website=imd.gov.in}}</ref>}}
{{climate chart|[[Turpan]], [[Xinjiang]], [[China]]
|-10.3|-2.3|0.9
|-3.5|7.0|0.5
|5.9|17.9|0.7
|14.2|27.8|0.9
|19.8|33.9|1.0
|24.7|38.8|2.6
|26.5|40.5|2.0
|24.6|39.0|2.0
|18.4|32.6|1.4
|9.1|22.5|1.2
|0.3|10.3|0.6
|-7.6|-0.4|0.9
|float=left
|clear=none
|source=[[China Meteorological Administration]]<ref name="cma graphical">{{cite web |url=http://data.cma.cn/data/weatherBk.html |script-title=zh:中国气象数据网 – WeatherBk Data |publisher=[[China Meteorological Administration]] |language=zh-hans |access-date=10 October 2023 |archive-date=5 September 2018 |archive-url=https://web.archive.org/web/20180905194950/http://data.cma.cn/data/weatherBk.html |url-status=live }}</ref><ref>{{cite web |url=https://experience.arcgis.com/template/e724038fda394e9d9b7921f10fd1aa55/page/%E7%BA%AF%E8%A1%A8%E6%A0%BC%E7%BB%9F%E8%AE%A1-(%E5%AF%B9%E6%AF%948110%E5%8F%98%E5%8C%96)/?org=UQmaps |script-title=zh:中国气象数据网 |publisher=[[China Meteorological Administration]] |language=zh-hans |access-date=10 October 2023 |archive-date=4 April 2023 |archive-url=https://web.archive.org/web/20230404092524/https://experience.arcgis.com/template/e724038fda394e9d9b7921f10fd1aa55/page/%E7%BA%AF%E8%A1%A8%E6%A0%BC%E7%BB%9F%E8%AE%A1-(%E5%AF%B9%E6%AF%948110%E5%8F%98%E5%8C%96)/?org=UQmaps |url-status=live }}</ref>}}
{{climate chart|[[Antofagasta]], [[Chile]]
|17.4|23.6|0.0
|17.2|23.6|0.0
|16.2|22.6|0.8
|14.6|20.5|0.1
|13.3|18.8|0.2
|12.3|17.3|1.5
|11.7|16.5|0.4
|12.2|16.8|0.8
|12.9|17.4|0.2
|13.9|18.5|0.2
|15.1|20.1|0.1
|16.2|21.8|0.1
|float=left
|clear=right
|source=Dirección Meteorológica de Chile<ref name=climatenormals>{{cite web
| url = https://climatologia.meteochile.gob.cl/application/historico/datosNormales/230001
| title = Datos Normales y Promedios Históricos Promedios de 30 años o menos
| publisher = Dirección Meteorológica de Chile
| language = es
| access-date = 20 May 2023
| archive-url = https://web.archive.org/web/20230521022007/https://climatologia.meteochile.gob.cl/application/historico/datosNormales/230001
| archive-date = 21 May 2023
| url-status = live
}}</ref>}}
{{Clear}}
== See also ==
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