Polar climate

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Areas of polar climate according to the Koppen climate classification.
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Tundra climate (ET)
Ice cap climate (EF) Koppen-Geiger Map E present.svg
Areas of polar climate according to the Köppen climate classification.
   Tundra climate (ET)
   Ice cap climate (EF)
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. Oblique rays 04 Pengo.svg
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.

The polar climate regions are characterized by a lack of warm summers but with varying winters. Every month in a polar climate has an average temperature of less than 10 °C (50 °F). Regions with polar climate cover more than 20% of the Earth's area. Most of these regions are far from the equator and near the poles, and in this case, winter days are extremely short and summer days are extremely long (could last for the entirety of each season or longer). A polar climate consists of cool summers and very cold winters, which results in treeless tundra, glaciers, or a permanent or semi-permanent layer of ice. It is identified with the letter E in the Köppen climate classification.

Contents

Subtypes

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 0 °C (32 °F), while an ice cap climate has no months averaging above 0 °C (32 °F). [2] In a tundra climate, even coniferous trees cannot grow, but other specialized plants 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 10 °C (50 °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

A polar bear with cub Ursus maritimus mother with cub.jpg
A polar bear with cub

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 Eurasian 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 10 °C (50 °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

A map of the Arctic. The red line indicates the 10degC isotherm in July and the white area shows the average minimum extent of sea ice in summer as of 1975. Arctic big.svg
A map of the Arctic. The red line indicates the 10°C isotherm in July and the white area shows the average minimum extent of sea ice in summer as of 1975.

Some parts of the Arctic are covered by ice (sea ice, 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 −40 to 0 °C (−40 to 32 °F), and winter temperatures can drop below −50 °C (−58 °F) over large parts of the Arctic. Average July temperatures range from about −10 to 10 °C (14 to 50 °F), with some land areas occasionally exceeding 30 °C (86 °F) in summer.

The Arctic consists of 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 −2 °C (28 °F). In winter, this relatively warm water, even though covered by the 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 climates.

Antarctica

The climate of Antarctica is the coldest on Earth. Antarctica has the lowest naturally occurring temperature ever recorded: −89.2 °C (−128.6 °F) at Vostok Station. [4] It is also extremely dry (technically a desert, or so called polar desert), averaging 166 millimetres (6.5 in) of precipitation per year, as weather fronts 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. All 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, have ice cap climate. Only the summit of Mount Rainier has an ice cap climate in the Cascade Range.

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 10 °C (50 °F) summer isotherm; i.e., places where the average temperature in the warmest calendar month of the year is below the fixed threshold of 10 °C (50 °F) cannot support forests. See Köppen climate classification for more information.

Otto Nordenskjöld theorized that winter conditions also play a role: His formula is 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 −20 °C (−4 °F) in its coldest month, the warmest month would need to average 11 °C (52 °F) or higher for trees to be able to survive there as 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 improved on these schemes, by defining biotemperature: the mean annual temperature, where all temperatures below 0 °C or 32 °F (and above 30 °C or 86 °F) are treated as 0 °C (because it makes no difference to plant life, being dormant). If the mean biotemperature is between 1.5 and 3 °C (34.7 and 37.4 °F), [5] Holdridge quantifies the climate as subpolar (or alpine, if the low temperature is caused by elevation).

See also

Related Research Articles

<span class="mw-page-title-main">Tundra</span> Biome where plant growth is hindered by frigid temperatures

In physical geography, tundra is a type of biome where the tree growth is hindered by frigid temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sámi word тӯндар meaning "uplands", "treeless mountain tract". There are three regions and associated types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra.

<span class="mw-page-title-main">Subarctic climate</span> Climate characterised by long, usually very cold winters, and short, cool summers

The subarctic climate is a climate characterised by long, cold winters, and short, warm to cool summers. It is found on large landmasses, often away from the moderating effects of an ocean, generally at latitudes from 50° to 70°N north, poleward of the humid continental climates. Subarctic or boreal climates are the source regions for the cold air that affects temperate latitudes to the south in winter. These climates represent Köppen climate classification Dfc, Dwc, Dsc, Dfd, Dwd and Dsd.

<span class="mw-page-title-main">Temperate climate</span> Main climate class

In geography, the temperate climates of Earth occur in the middle latitudes, which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout the year and more distinct seasonal changes compared to tropical climates, where such variations are often small and usually only have precipitation changes.

<span class="mw-page-title-main">Geography of Norway</span> Geographical features of Norway

Norway is a country located in Northern Europe in the northern and western parts of the Scandinavian Peninsula. The majority of the country borders water, including the Skagerrak inlet to the south, the North Sea to the southwest, the North Atlantic Ocean to the west, and the Barents Sea to the north. It has a land border with Sweden to the east and a shorter border with Finland and an even shorter border with Russia to the northeast.

Alpine tundra Biome found at high altitudes

Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets lower until it reaches sea level, and alpine tundra merges with polar tundra.

<span class="mw-page-title-main">Mediterranean climate</span> Type of climate

A Mediterranean climate, also called dry summer temperate climateCs, is a temperate climate sub-type, characterized by dry summers and mild, wet winters. The climate receives its name from the Mediterranean Basin, where this climate type is most common. Mediterranean climate zones are typically located along the western coasts of continents, between roughly 30 and 45 degrees north and south of the equator. The main cause of Mediterranean, or dry summer climate, is the subtropical ridge which extends toward that hemisphere's pole during the summer and migrates toward the equator during the winter due to the seasonal poleward-equatorward variations of temperatures.

<span class="mw-page-title-main">Köppen climate classification</span> Climate classification system

The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notably in 1918 and 1936. Later, the climatologist Rudolf Geiger (1894–1981) introduced some changes to the classification system, which is thus sometimes called the Köppen–Geiger climate classification system.

Alpine climate Typical weather for regions above the tree line

Alpine climate is the typical weather (climate) for the regions above the tree line. This climate is also referred to as a mountain climate or highland climate.

<span class="mw-page-title-main">Oceanic climate</span> Climate classification

An oceanic climate, also known as a marine climate, is the humid temperate climate sub-type in Köppen classification Cfb, typical of west coasts in higher middle latitudes of continents, generally featuring cool summers and mild winters, with a relatively narrow annual temperature range and few extremes of temperature. Oceanic climates can be found in both hemispheres normally between 40 and 55 latitude. Most notably in northwest Europe, northwest North America, as well as New Zealand.

Seasonal lag is the phenomenon whereby the date of maximum average air temperature at a geographical location on a planet is delayed until some time after the date of maximum insolation. This also applies to the minimum temperature being delayed until some time after the date of minimum insolation.

Polar desert Region of the Earth

Polar deserts are the regions of Earth that fall under an ice cap climate. Despite rainfall totals low enough to normally classify as a desert, polar deserts are distinguished from true deserts by low annual temperatures and evapotranspiration. Most polar deserts are covered in ice sheets, ice fields, or ice caps, and they are also called white deserts.

Polar ecology is the relationship between plants and animals in a polar environment. Polar environments are in the Arctic and Antarctic regions. Arctic regions are in the Northern Hemisphere, and it contains land and the islands that surrounds it. Antarctica is in the Southern Hemisphere and it also contains the land mass, surrounding islands and the ocean. Polar regions also contain the subantarctic and subarctic zone which separate the polar regions from the temperate regions. Antarctica and the Arctic lie in the polar circles. The polar circles are imaginary lines shown on maps to be the areas that receives less sunlight due to less radiation. These areas either receive sunlight or shade 24 hours a day because of the earth's tilt. Plants and animals in the polar regions are able to withstand living in harsh weather conditions but are facing environmental threats that limit their survival.

Climate classification Systems that categorize the worlds climates

Climate classifications are systems that categorize the world's climates. A climate classification may correlate closely with a biome classification, as climate is a major influence on life in a region. One of the most used is the Köppen climate classification scheme first developed in 1899.

Arctic vegetation Plants adapted to the short, cold growing seasons of the Arctic regions

About 1,702 species of plants live on the Arctic tundra, including flowering plants, short shrubs, herbs, grasses, mosses, and lichens. These plants are adapted to short, cold growing seasons. They have the ability to withstand extremely cold temperatures in the winter, and grow and reproduce in summer conditions that are quite limiting.

Climate of the Arctic Overview of the climate of the Arctic

The climate of the Arctic is characterized by long, cold winters and short, cool summers. There is a large amount of variability in climate across the Arctic, but all regions experience extremes of solar radiation in both summer and winter. Some parts of the Arctic are covered by ice year-round, and nearly all parts of the Arctic experience long periods with some form of ice on the surface.

Climate of the United States Varies due to changes in latitude, and a range of geographic features

The climate of the United States varies due to changes in latitude, and a range of geographic features, including mountains and deserts. Generally, on the mainland, the climate of the U.S. becomes warmer the further south one travels, and drier the further west, until one reaches the West Coast.

Climate of Norway Overview of the Climate of Norway

The climate of Norway is more temperate than could be expected for such high latitudes. This is mainly due to the North Atlantic Current with its extension, the Norwegian Current, raising the air temperature; the prevailing southwesterlies bringing mild air onshore; and the general southwest–northeast orientation of the coast, which allows the westerlies to penetrate into the Arctic. The January average in Brønnøysund is 14.6 °C (58.3 °F) warmer than the January average in Nome, Alaska, even though both towns are situated on the west coast of the continents at 65°N. In July, the difference is reduced to 2.9 °C (5.2 °F). The January average of Yakutsk, in Siberia but slightly further south, is 42.3 °C (108.1 °F) colder than in Brønnøysund.

North American Arctic

The North American Arctic is composed of the northern polar regions of Alaska (USA), Northern Canada and Greenland. Major bodies of water include the Arctic Ocean, Hudson Bay, the Gulf of Alaska and North Atlantic Ocean. The North American Arctic lies above the Arctic Circle. It is part of the Arctic, which is the northernmost region on Earth. The western limit is the Seward Peninsula and the Bering Strait. The southern limit is the Arctic Circle latitude of 66° 33’N, which is the approximate limit of the midnight sun and the polar night.

Ice cap climate Polar climate where no mean monthly temperature exceeds 0 °C (32 °F)

An ice cap climate is a polar climate where no mean monthly temperature exceeds 0 °C (32 °F). The climate covers areas in or near the high latitudes to polar regions, such as Antarctica, some of the northernmost islands of Canada and Russia, Greenland, along with some regions and islands of Norway's Svalbard Archipelago that have vast deserts of snow and ice. Areas with ice cap climates are normally covered by a permanent layer of ice and have no vegetation. There is limited animal life in most ice cap climates, usually found near the oceanic margins. Although ice cap climates are inhospitable to human life, there are some small research stations scattered in Antarctica and interior Greenland.

<span class="mw-page-title-main">Trewartha climate classification</span> Categorical system for longer-range recurrent weather patterns of Earth, orig. 1966

The Trewartha climate classification (TCC) or the Köppen–Trewartha climate classification (KTC) is a climate classification system first published by American geographer Glenn Thomas Trewartha in 1966. It is a modified version of the Köppen–Geiger system, created to answer some of its deficiencies. The Trewartha system attempts to redefine the middle latitudes to be closer to vegetation zoning and genetic climate systems. It was considered a more true or "real world" reflection of the global climate.

References

  1. Yung, Chung-hoi. "Why is the equator very hot and the poles very cold?". Hong Kong Observatory. Archived from the original on 2018-06-14. Retrieved 2010-12-02.
  2. McKnight, Tom L; Hess, Darrel (2000). "Climate Zones and Types: The Köppen System" . Physical Geography: A Landscape Appreciation. Upper Saddle River, NJ: Prentice Hall. pp.  235–7. ISBN   978-0-13-020263-5.
  3. PD-icon.svg This article incorporates  public domain material from the CIA World Factbook website https://web.archive.org/web/20070613024704/https://www.cia.gov/library/publications/the-world-factbook/reference_maps/pdf/arctic.pdf .
  4. Gavin Hudson (2008-12-14). "The Coldest Inhabited Places on Earth". Eco Worldly. Archived from the original on 2008-12-18. Retrieved 2009-02-08.
  5. Jones, Allan. "Biodiversity lectures and practicals". University of Dundee. Archived from the original on 2007-09-29.