|
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 (midnight sun) or shade (polar night) 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== Polar climates are cold, windy and dry. Because of the lack of precipitation and low temperatures the Arctic and Antarctic are considered the world's largest deserts or Polar deserts.〔(The World's Largest Deserts )〕〔(Types of Seserts )〕 Much of the radiation from the sun that is received is reflected off the snow making the polar regions cold.〔Stonehouse, 23〕 When the radiation is reflected, the heat is also reflected. The polar regions reflect 89-90% of the sun radiation that the earth receives.〔Stonehouse, 24〕 And because Antarctica is closer to the sun at perihelion, it receives 7% more radiation than the Arctic.〔(Factors affecting surface ultraviolet radiation levels in the Arctic )〕 Also in the polar region, the atmosphere is thin. Because of this the UV radiation that gets to the atmosphere can cause fast sun tanning and snow blindness. Polar regions are dry areas; there is very little precipitation due to the cold air. There are some times when the humidity may be high but the water vapor present in the air may be low. Wind is also strong in the polar region. Wind carries snow creating blizzard like conditions. Winds may also move small organisms or vegetation if it is present.〔Stonehouse, 44〕 The wind blows the snow making snowdrifts or snow dunes which may exist even in the spring when the snow is thawing out.〔 It is hard for meteorologists to measure the amount of precipitation. This is because it is expensive to take care of the stations that collect weather data and it hard for them to measure snow fall amounts because the wind blows the snow too much to calculate exact amounts. The temperatures are similar between the Arctic and Antarctic. The temperatures in the Arctic are different depending on the location. Temperatures in the Arctic have a higher range than in the Antarctic. Temperatures can range as much as . Along the coast in the Arctic temperatures average in December, January and February.〔Stonehouse, 48〕 The ice melts along the coast during the summer months which are around June, July and August and the temperature may rise a few degrees above freezing causing there to be some vegetation. During these same months in the northern regions there will be 24 hours of daylight. Arctic regions also receive a lot of snowfall. The Arctic Basin has snow 320 days out of the year while the Arctic Seas have snow cover 260 days a year.〔 The thickness of the snow averages .〔Melnikov, 14〕 In Greenland, temperatures have an average temperature of in the winter and in the summer the temperatures reach . Iceland on the other hand is in a subarctic region meaning it is near the temperate zone. Because of this the temperatures are above the freezing point throughout much of the year. In Russia temperatures are extremely cold. In Verkhoyansk, Siberia it has reached the coldest temp of in the Northern Hemisphere.〔Stonehouse, 51〕 The temperatures in the summer in Siberia can get to . In the Antarctic there is less temperature variations. Temperatures only range by around . The winter months are May till September while the summer months will be October till April. The sun reappears in September which then starts the 24 hours of daylight. The temperatures are different between the plateaus in Antarctica and between the coasts. The plateaus are the coldest regions of Antarctica.〔Stonehouse, 52〕 In the summer months there is low precipitation with light winds. Vostok has received the lowest temperature worldwide getting as low as in 1960. The West Antarctica plateau reaches snow levels of around . This area is also warmer but it receives the heaviest snow and receives more wind. Because of the cold desert like conditions on the plateaus there are very little plants and animals. Some species of birds though have been seen. On the coasts in the summer there is more wind, and it is cloudier. Coasts with higher latitudes have a temperature of in the winter months whereas lower latitude coasts get down to . Coastal areas may receive or more of snow. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Polar ecology」の詳細全文を読む スポンサード リンク
|