The polar regions, also called the frigid zones or polar zones, of Earth are the regions of the planet that surround its

geographical pole A geographical pole or geographic pole is either of the two points on Earth where its axis of rotation intersects its surface. The North Pole lies in the Arctic Ocean while the South Pole is in Antarctica. North and South poles are also define ...

s (the North and South Poles), lying within the polar circles. These high latitudes are dominated by floating

sea ice Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oce ...

covering much of the Arctic Ocean in the north, and by the

Antarctic ice sheet The Antarctic ice sheet is one of the two polar ice caps of Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth, with an average thickness of over 2 kilometers. It covers an area of almost and ...

on the continent of Antarctica and the Southern Ocean in the south.

Definitions

The Arctic has various definitions, including the region north of the

Arctic Circle The Arctic Circle is one of the two polar circles, and the most northerly of the five major circles of latitude as shown on maps of Earth. Its southern equivalent is the Antarctic Circle. The Arctic Circle marks the southernmost latitude at w ...

(currently Epoch 2010 at 66°33'44" N), or just the region north of 60° north latitude, or the region from the North Pole north to the timberline. The

Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...

is usually defined simply as south of 60° south latitude, or the continent of Antarctica. The 1959 Antarctic Treaty uses the former definition. The two polar regions are distinguished from the other two climatic and biometric belts of Earth, a tropics belt near the equator, and two

middle latitude The middle latitudes (also called the mid-latitudes, sometimes midlatitudes, or moderate latitudes) are a spatial region on Earth located between the Tropic of Cancer (latitudes 23°26'22") to the Arctic Circle (66°33'39"), and Tropic of Caprico ...

regions located between the tropics and ''polar regions''.

Climate

Polar regions receive less intense solar radiation than the other parts of Earth because the Sun's energy arrives at an

oblique angle In Euclidean geometry, an angle is the figure formed by two rays, called the '' sides'' of the angle, sharing a common endpoint, called the ''vertex'' of the angle. Angles formed by two rays lie in the plane that contains the rays. Angles are ...

, spreading over a larger area, being less concentrated, and also travels a longer distance through the Earth's atmosphere in which it may be absorbed, scattered or reflected, which is the same thing that causes winters to be colder than the rest of the year except in tropical regions. The axial tilt of the Earth has the most effect on climate of the polar regions due to its latitude. However, since the polar regions are the farthest from the

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...

, they receive the weakest solar radiation and are therefore generally frigid year round due to the earth's axial tilt of 23.5° not being enough to create a high maximum midday

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...

to sufficiently compensate the Sun's rays for the high latitude even in summer, except for relatively brief periods in peripheral areas near the polar circles. The large amount of ice and snow also reflects and weakens of what weak sunlight the polar regions receive further, contributing to the cold. Polar regions are characterized by extremely cold temperatures, heavy glaciation wherever there is sufficient precipitation to form permanent ice, short and still cold summers, and extreme variations in daylight hours, with twenty-four hours of daylight in summer, and complete darkness at

mid-winter Midwinter is the middle of the winter. The term is attested in the early Germanic calendars. Attestations Midwinter is attested in the early Germanic calendars, where it appears to have been a specific day or a number of days during the winter ha ...

Circumpolar Arctic region

There are many settlements in Earth's north polar region. Countries with claims to Arctic regions are: the United States ( Alaska), Canada ( Yukon, the

Northwest Territories The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. ...

and

Nunavut Nunavut ( , ; iu, ᓄᓇᕗᑦ , ; ) is the largest and northernmost Provinces and territories of Canada#Territories, territory of Canada. It was separated officially from the Northwest Territories on April 1, 1999, via the ''Nunavut Act'' ...

), Denmark ( Greenland), Norway, Finland,

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

, Iceland, and Russia. Arctic circumpolar populations, though small, often share more in common with each other than with other populations within their national boundaries. As such, the northern polar region is diverse in human settlements and cultures.

Antarctica and the Southern sea

The southern polar region has no permanent human habitation as of now.

McMurdo Station McMurdo Station is a United States Antarctic research station on the south tip of Ross Island, which is in the New Zealand-claimed Ross Dependency on the shore of McMurdo Sound in Antarctica. It is operated by the United States through the Unit ...

is the largest research station in Antarctica, run by the United States. Other notable stations include Palmer Station and

Amundsen–Scott South Pole Station The Amundsen–Scott South Pole Station is the United States scientific research station at the South Pole of the Earth. It is the southernmost point under the jurisdiction (not sovereignty) of the United States. The station is located on the ...

(United States), Esperanza Base and Marambio Base ( Argentina), Scott Base ( New Zealand), and Vostok Station (Russia). While there are no indigenous human cultures, there is a complex ecosystem, especially along Antarctica's coastal zones. Coastal upwelling provides abundant nutrients which feeds krill, a type of marine

Crustacea Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

, which in turn feeds a complex of living creatures from penguins to blue whales.

References

External links

*
The Polar Regions

International Polar Foundation

Arctic Environmental Atlas (UNDP)

Scott Polar Research Institute, University of Cambridge

WWF:The Polar Regions

World Environment Day 2007 "Melting Ice" image gallery at The Guardian

Polar Discovery
{{DEFAULTSORT:Polar Regions Of Earth Geography of Antarctica Arctic Ocean Geography of the Arctic Articles containing video clips