Editing Polar climate

{{Short description|Climate classification}}
[[File:Koppen-Geiger_Map_v2_E_1991–2020.svg|thumb|upright=1.8|Areas of polar climate according to  the [[Köppen climate classification]]:
{{legend|#E2E2E2|[[Tundra climate]] ''(ET)''}}
{{legend|#565656|[[Ice cap climate]] ''(EF)''}}]]
[[Image:Oblique rays 04 Pengo.svg|thumb|upright=1.25|Solar radiation has a lower intensity in polar regions because the angle at which it hits the earth is not as direct as at the equator. Another effect is that sunlight has to go through more atmosphere to reach the ground.<ref>{{cite web|url=http://www.hko.gov.hk/education/edu06nature/ele_srad_e.htm|title=Why is the equator very hot and the poles very cold?|last=Yung|first=Chung-hoi|publisher=Hong Kong Observatory|access-date=2010-12-02|archive-date=2018-06-14|archive-url=https://web.archive.org/web/20180614094310/http://www.hko.gov.hk/education/edu06nature/ele_srad_e.htm|url-status=dead}}</ref>]]

The '''polar climate''' regions are characterized by a lack of warm [[summer]]s but with varying [[winter]]s. Every month a polar climate has an average temperature of less than {{convert|10|C|F}}. Regions with a polar climate cover more than 20% of the Earth's area. Most of these regions are far from the [[equator]] and near the [[Polar regions of Earth|poles]], and in this case, winter days are extremely short and summer days are extremely long (they could last for the entirety of each season or longer). A polar climate consists of cool summers and very cold winters (or, in the case of ice cap climates, no real summer at all), which results in treeless [[tundra]]s, [[glacier]]s, or a permanent or semi-permanent layer of [[ice]]. It is identified with the letter '''E''' in the [[Köppen climate classification]].

==Subtypes==
{{Main|Ice cap climate|Tundra climate}}

There are two types of polar climate: '''ET''', or [[tundra climate]]; and '''EF''', or [[ice cap climate]]. A tundra climate is characterized by having at least one month whose average temperature is above {{convert|0|C|F}}, while an ice cap climate has no months averaging above {{convert|0|C|F}}.<ref>{{cite book | last1=McKnight | first1=Tom L | last2=Hess | first2=Darrel | year=2000 | chapter=Climate Zones and Types: The Köppen System | title=Physical Geography: A Landscape Appreciation | pages=[https://archive.org/details/physicalgeographmckn/page/235 235–7] | location=Upper Saddle River, NJ | publisher=Prentice Hall | isbn=978-0-13-020263-5 | chapter-url-access=registration | chapter-url=https://archive.org/details/physicalgeographmckn | url=https://archive.org/details/physicalgeographmckn/page/235 }}</ref> In a tundra climate, even [[coniferous]] trees cannot grow, but other specialized plants such as the arctic poppy can grow. In an ice cap climate, no plants can grow, and ice gradually accumulates until it flows or slides elsewhere. Many [[high altitude]] locations on Earth have a climate where no month has an average temperature of {{convert|10|C|F}} or higher, but as this is due to elevation, this climate is referred to as [[Alpine climate]]. Alpine climate can mimic either tundra or ice cap climate.

== Locations ==
[[File:Laponie007.jpg|thumb|left|A snowy landscape of [[Inari, Finland|Inari]] located in [[Lapland (Finland)|Lapland]] ([[Finland]])]]
[[File:Ursus maritimus mother with cub.jpg|A [[polar bear]] with cub|right|thumb]]
On Earth, the only continent where the ice cap polar climate is predominant is [[Antarctica]]. All but a few isolated coastal areas on the island of [[Greenland]] also have the ice cap climate. Summits of many high mountains also have ice cap climate due to their high elevation. Coastal regions of Greenland that do not have permanent ice sheets have the less extreme tundra climates. The northernmost part of the [[Eurasia]]n land mass, from the extreme northeastern coast of [[Scandinavia]] and eastwards to the [[Bering Strait]], large areas of northern [[Siberia]] and northern [[Iceland]] have tundra climate as well. Large areas in northern [[Canada]] and northern [[Alaska]] have tundra climate, changing to ice cap climate in the most northern parts of Canada. Southernmost [[Argentina]] ([[Tierra del Fuego]] where it abuts the [[Drake Passage]]) and such subantarctic islands such as the [[South Shetland Islands]] and the [[Falkland Islands]] have [[tundra]] climates of slight [[temperature]] range in which no month is as warm as {{convert|10|C|F}}. These subantarctic lowlands are found closer to the [[equator]] than the coastal tundras of the Arctic basin. Summits of many mountains of [[Earth]] also have polar climates, due to their higher elevations.

===Arctic===
{{Main|Climate of the Arctic}}
[[Image:Arctic big.svg|thumb|upright=1.4|A map of the Arctic. The red line indicates the 10°C [[isotherm (contour line)|isotherm]] in July and the white area shows the average minimum [[Measurement of sea ice#Sea ice extent|extent of sea ice]] in [[summer]] as of 1975.<ref>{{CIA World Factbook|url=https://web.archive.org/web/20070613024704/https://www.cia.gov/library/publications/the-world-factbook/reference_maps/pdf/arctic.pdf}}</ref>]]
Some parts of the Arctic are covered by ice ([[sea ice]], [[glacier|glacial ice]], or [[snow]]) year-round, especially at the most poleward parts; and nearly all parts of the Arctic experience long periods with some form of ice or snow on the surface. Average January temperatures range from about {{convert|−40|to|0|C|F}}, and winter temperatures can drop below {{convert|−50|C|F}} over large parts of the Arctic. Average July temperatures range from about {{convert|−10|to|10|C|F}}, with some land areas occasionally exceeding {{convert|30|C|F}} in summer.

The Arctic consists of an [[Arctic Ocean|ocean]] that is almost surrounded by landmasses like [[Russia]] and [[Canada]]. As such, the [[climate]] of much of the [[Arctic]] is moderated by the ocean water, which can never have a temperature below {{convert|−2|C|F}}. In winter, this relatively warm water, even though covered by the [[Arctic ice pack|polar ice pack]], keeps the [[North Pole]] from being the coldest place in the [[Northern Hemisphere]], and it is also part of the reason that [[Antarctica]] is so much colder than the Arctic. In summer, the presence of the nearby water keeps coastal areas from warming as much as they might otherwise, just as it does in [[temperate]] regions with [[maritime climate]]s.

===Antarctica===
{{Main|Climate of Antarctica}}
The [[climate]] of [[Antarctica]] is the coldest on [[Earth]]. Antarctica has the lowest naturally occurring [[temperature]] ever recorded: {{convert|−89.2|C|F}} at [[Vostok, Antarctica|Vostok Station]] in 1983.<ref name = "ecoworldly coldest">{{cite web|url=http://ecoworldly.com/2008/12/14/the-coldest-inhabited-places-on-earth/ |archive-url=https://web.archive.org/web/20081218000756/http://ecoworldly.com/2008/12/14/the-coldest-inhabited-places-on-earth/ |archive-date=2008-12-18|title=The Coldest Inhabited Places on Earth |publisher=Eco Worldly |date=2008-12-14 |author=Gavin Hudson |access-date=2009-02-08}}</ref> It is also extremely dry (technically a [[desert]], or so called [[polar desert]]), averaging {{convert|166|mm|in}} of [[Precipitation (meteorology)|precipitation]] per year, as [[weather front]]s rarely penetrate far into the continent.

=== Mountains ===
Summits of most mountains also have polar climates, despite being in lower latitudes, due to their high elevations. The highest mountains of the [[Rocky Mountains]], [[Alps]], and the [[Caucasus]] have tundra climate. Some mountains of the [[Andes]], the [[Saint Elias Mountains]], and most mountains of the [[Himalayas]], the [[Karakoram]], the [[Hindu Kush Range]], [[Pamir Mountains]], the [[Tian Shan Mountains]], and the [[Alaska Range]] also have ice cap climates at extremely high elevations, in addition to tundra climates at relatively lower elevations. Only the summit of [[Mount Rainier]] has an ice cap climate in the [[Cascade Range]].{{cn|date=May 2025}}

==Quantifying polar climate==
There have been several attempts at quantifying what constitutes a polar climate.

Climatologist [[Wladimir Köppen]] demonstrated a relationship between the Arctic and Antarctic tree lines and the {{convert|10|C|F}} summer isotherm; i.e., places where the average temperature in the warmest calendar month of the year is below the fixed threshold of {{convert|10|C|F}} cannot support forests. See [[Köppen climate classification]] for more information.

[[Otto Nordenskjöld]] theorized that winter conditions also play a role: His formula is {{nowrap|1=''W'' = 9 − 0.1 ''C''}}, where ''W'' is the average temperature in the warmest month and ''C'' the average of the coldest month, both in degrees Celsius. For example, if a particular location had an average temperature of {{convert|−20|C|F}} in its coldest month, the warmest month would need to average {{convert|11|C|F}} or higher for trees to be able to survive there as {{nowrap|1=9 − 0.1(−20) = 11}}. Nordenskiöld's line tends to run to the north of Köppen's near the west coasts of the Northern Hemisphere continents, south of it in the interior sections, and at about the same latitude along the east coasts of both Asia and North America. In the Southern Hemisphere, all of [[Tierra del Fuego]] lies outside the polar region in Nordenskiöld's system, but part of the island (including [[Ushuaia]], [[Argentina]]) is reckoned as being within the Antarctic under Köppen's.

In 1947, [[Holdridge life zone|Holdridge improved on these schemes]], by defining [[biotemperature]]: the mean annual temperature, where all temperatures below {{convert|0|C|F|disp=or}} (and above {{convert|30|C|F|disp=or}}) are treated as 0&nbsp;°C (because it makes no difference to plant life, being dormant). If the mean biotemperature is between {{convert|1.5|and|3|C|F}},<ref>{{cite web|url=http://www.personal.dundee.ac.uk/~amjones/dundee/36biomes.htm|title=Biodiversity lectures and practicals|first=Allan|last=Jones|publisher=University of Dundee|archive-url=https://web.archive.org/web/20070929131915/http://www.personal.dundee.ac.uk/~amjones/dundee/36biomes.htm |archive-date=2007-09-29 }}</ref> Holdridge quantifies the climate as [[subarctic climate|subpolar]] (or alpine, if the low temperature is caused by elevation).

==See also==
* [[Arctic oscillation]]
* [[Climate change in the Arctic]]
* [[Global warming in Antarctica]]

==References==
{{Reflist}}

==External links==
{{Commons and category}}
* [http://www.arctic.noaa.gov/soa2006/ NOAA State of the Arctic Report 2006]

{{Arctic topics}}
{{Koppen}}
{{Authority control}}

[[Category:Köppen climate types]]
[[Category:Polar regions of the Earth]]