Earth Science: Subpolar and Polar Climate
Distinct seasons occur within the polar circles. However, during the winter, the sun never fully rises and in the extreme cases of the North and South Poles, the polar night and polar day last half a year each.
The subpolar climate zone is the transition between the temperate and the polar climate zone. It is a relatively narrow belt along the coast of the Arctic Ocean from northern Scandinavia through Siberia to Alaska, northern Canada, and Greenland. The mean temperature of the warmest months during the short summer is below 50°F (10°C) and the winters are moderate to extremely cold.
There is also a marked contrast between the mild oceanic climate and extremely continental climate. Precipitation usually falls throughout the year, but only little. Winds are often strong, especially in the Southern Hemisphere and close to the boundary of the West Wind Drift. Durable and low-growing plants such as lichen, moss, and grasses, herbaceous and scrub species have adapted very well to the rough climate, short growth period, and permafrost.
They form the tundra, which covers large parts of the subpolar zone. The treeless tundra may even cover areas south of the northern polar circle that are elevated or exposed to the wind. Toward the north, the tundra is adjacent to the polar desert.
Polar areas
The polar areas of the Earth are cold deserts. Temperatures are constantly below freezing and solar radiation is reduced. Major parts of the Arctic are occupied by the Arctic Ocean that is covered over by pack ice. Due to the heat capacity of the water, the most extreme temperatures are not at the North Pole but in eastern Siberia where temperatures reach -94°F (-70°C).
The sixth continent, Antarctica, is covered by an ice sheet of several miles thickness. With temperatures as low as -128.6°F (-89.2°C), Antarctica is the coldest place on Earth; even during the summer, the thermometer never rises above 5°F (-15°C). Temperatures are so low due to the elevation and the circumpolar current.
Only little water can evaporate in such a cold climate, therefore, very little precipitation falls in this area. Annual precipitation is between 1.2 inches (30 mm) in the interior of the Antarctic and 5.9 inches (150 mm) near the coast; in the Arctic it is between 2 and 19.7 inches (50 and 500 mm). Cold katabatic winds are typical for the climate of the Antarctic.
They can lead to severe storms. In this almost completely unvegetated zone, life is concentrated in the coastal areas, which are slightly warmer, similarly to the Arctic. This is where animals that have adapted to the polar climate can find sufficient food. A vast habitat for plankton and fish, the Arctic Ocean and the Southern Ocean are among the most productive regions on Earth.
MOUNTAIN CLIMATE
Climate does not only depend on latitude. High mountains are a special case in all climate zones. Temperatures drop with altitude, just like they drop from the Equator toward the Poles. They drop by about 33°F per 328 feet (0.6°C per 100 m).
This results in various climate and vegetation zones. Elevation climate zones are especially distinct in the tropical mountains, where they range from tropical rain forest to forest, tree, and snow boundaries and finally to the permanent ice zone.