Polar regions of Earth

Visualization of the ice and snow covering Earth's north and south polar regions

Northern Hemisphere permafrost (permanently frozen ground) in purple

The polar regions of Earth, also known as Earth's frigid zones, are the regions of Earth surrounding its geographical poles (the North and South Poles). These regions are dominated by Earth's polar ice caps, the northern resting on the Arctic Ocean and the southern on the continent of Antarctica.

Terrestrial polar regions

Definitions

The Arctic has various definitions, including the region north of the Arctic Circle (currently Epoch 2010 at 66°33'44" N), or the region north of 60° north latitude, or the region from the North Pole south to the timberline. The Antarctic is usually defined 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 biomatic belts of Earth, a tropics belt near the equator, and two middle latitude 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, spreading over a larger area, 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 in temperate areas.

The axial tilt of the Earth has a major effect on climate of the polar regions. Since the polar regions are the farthest from the equator, they receive the least amount of sunlight and are therefore frigid. The large amount of ice and snow also reflects a large part of what little sunlight the Polar regions receive, contributing to the cold. Polar regions are characterized by the polar climate, extremely cold temperatures, heavy glaciation wherever there is sufficient precipitation to form permanent ice, and extreme variations in daylight hours, with twenty-four hours of daylight in summer, and complete darkness at mid-winter.

Circumpolar Arctic region

North polar region polar bears

There are many settlements in Earth's north polar region. Countries with claims to Arctic regions are: the United States (Alaska), Canada, Denmark (Greenland), Norway, Finland, Sweden, Iceland, and Russia. Arctic circumpolar populations 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

South polar region penguin

The southern polar region has no permanent human habitation. McMurdo Station is the largest research station in Antarctica, run by the United States. Other notable stations include Palmer Station and Amundsen–Scott South Pole Station (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, which in turn feeds a complex of living creatures from penguins to blue whales.

Extraterrestrial polar regions

Other planets and natural satellites in the solar system have interesting quirks about their polar regions. Earth's Moon is thought to contain substantial deposits of ice in deep craters in its polar regions, which never see direct sunlight. Mars, like Earth, has polar ice caps. Meanwhile, on Uranus, the extreme tilt of the planet's axis leads to the poles alternately pointing almost directly at the Sun.

See also

Antarctic Antarctica Ecozone Expeditions Geography History Antarctic and sub-Antarctic islands

Arctic Arctic Arctic exploration Arctic Circle Arctic Ocean Canadian Arctic Archipelago Arctic cooperation and politics

Polar Geographical pole North Pole South Pole Geographical zone Polar drift Polar low

References

External links

• Polar regions at DMOZ
• The Polar Regions
• International Polar Foundation
• Arctic Environmental Atlas (UNDP)
• Earth's Polar Regions on Windows to the Universe
• Arctic Studies Center, Smithsonian Institution
• Scott Polar Research Institute, University of Cambridge
• WWF:The Polar Regions
• World Environment Day 2007 "Melting Ice" image gallery at The Guardian
• Polar Discovery

Further reading

• Victor, Paul-Émile. Man and the Conquest of the Poles, trans. by Scott Sullivan. New York: Simon & Schuster, 1963.