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 World Map ET and EF (Polar).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. 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 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.

Contents

Subtypes

There are two types of polar climate: ET and TY, 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 above 0 °C (32 °F). [2] [ clarification needed ] In a tundra climate, 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 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. 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 temperaturel 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.

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, and nearly all parts of the Arctic experience long periods with some form of ice 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 land. 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), averaging 166 millimetres (6.5 in) of precipitation per year, as weather fronts rarely penetrate far into the continent.

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 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

Climate Statistics of weather conditions in a given region over long periods

Climate is the long-term pattern of weather in an area, typically averaged over a period of 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation. In a broader sense, climate is the state of the components of the climate system, which includes the ocean, land, and ice on Earth. The climate of a location is affected by its latitude/longitude, terrain, and altitude, as well as nearby water bodies and their currents.

Tundra Biome where plant growth is hindered by cold temperatures

In physical geography, tundra is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sámi word тӯндар meaning "uplands", "treeless mountain tract". Tundra vegetation is composed of dwarf shrubs, sedges, grasses, mosses, and lichens. Scattered trees grow in some tundra regions. The ecotone between the tundra and the forest is known as the tree line or timberline. The tundra soil is rich in nitrogen and phosphorus.

Subarctic climate

The subarctic climate is a climate characterised by long, usually very cold winters, and short, cool summers. It is found on large landmasses, away from the moderating effects of an ocean, generally at latitudes from 50° to 70°N 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.

Temperate climate 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.

Geography of Norway

Norway is a country located in Northern Europe on 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.

Mediterranean climate Type of climate

A Mediterranean climate or dry summer climate is 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 sides of continents, between roughly 30 and 40 degrees north and south of the equator. The main cause of Mediterranean, or dry summer climate, is the subtropical ridge which extends northwards during the summer and migrates south during the winter due to increasing north–south temperature differences.

Subtropics Geographic and climate zone

The subtropical zones or subtropics are geographic and climate zones located to the north and south of the tropical zone. Geographically part of the north and south temperate zones, they cover the latitudes between 23°26′11.3″ (or 23.43648°) and approximately 35° in the northern and southern hemispheres.

Köppen climate classification 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

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.

Oceanic climate Climate classification

An oceanic climate, also known as a maritime climate or marine climate, is the Köppen classification of climate typical of west coasts in higher middle latitudes of continents, generally featuring mild summers and cool but not cold winters, with a relatively narrow annual temperature range and few extremes of temperature. Oceanic climates can be found in both temperate and subtropical areas, notably in Western Europe, parts of central and Southern Africa, North America, South America, parts of Asia, and as well as parts of Australia and 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 Regions of Earth under an ice cap with very low rainfall and no vegetation; type EF under the Köppen classification

Ice 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.

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 not visible on the earth but it is 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 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.

North American Arctic

The North American Arctic is composed of the northern portions 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

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.

Trewartha climate classification Method of classifying the worlds climates

The Trewartha climate classification 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.

Kalaallit Nunaat low arctic tundra

The Kalaallit Nunaat low arctic tundra ecoregion covers the low coastal areas of western and southern Greenland, reaching in up to 100 km before bare rock and ice become dominant. While much of the ecoregion is bare rock or ice, about 50% of the ground is covered in moss and lichen, and another 10% in herbaceous cover, shrubs, and even small stands of trees.

References

  1. Yung, Chung-hoi. "Why is the equator very hot and the poles very cold?". Hong Kong Observatory. 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.