Antarctica has the coldest climate on Earth. The lowest Antarctic air temperature record was set on July 21, 1983, with -89.2 Â ° C (-128.6 ° F) at Vostok Station. Satellite measurements have identified a lower soil temperature, up to -93.2 Â ° C (-135.8 Â ° F) in the Eastern Antarctic Plateau on August 10, 2010. It is also very dry (technically desert), on average 166 mm (6.5Ã, in) precipitation per year. On most continents, snow rarely melts and eventually compacts into glacier ice that forms ice sheets. The weather front rarely penetrates deep into the continent, due to the katabatic wind. Most of Antarctica has a climate of ice cover (KÃÆ'¶ppen EF ) with very cold weather, generally very dry.
Video Climate of Antarctica
Temperature
The lowest reliable temperature measured from the station occupied continuously on Earth -89.2 Â ° C (-128.6 ° F) is on July 21, 1983 at Vostok Station. As a comparison, this is 10.7 ° C (19.3 ° F) cooler than dry ice is fertile (at sea level pressure). Location altitude is 3,900 meters (12,800 feet).
The lowest recorded temperature of any location on the surface of the Earth is -93.2 ° C (-135.8 ° F) in the 81.8 Â ° S 63,5 Â E / -81,8; 63.5 , located in the unnamed Antarctic plateau between Dome A and Dome F, on August 10, 2010. The temperature is reduced from the jets measured by the satellite Landsat 8, and was found during the National Snow and Ice Center data from data retained in December 2013. This temperature is not directly proportional to the -89.2 quoted above, since it is the skin temperature inferred from the measured ray beam by satellite, than a thermometer - measures the air temperature of 1.5 m (4.9 ft) above ground level.
On the coast, the average Antarctic temperatures are about -10 Â ° C (in the hottest part of Antarctica) and on their plateau average about -55 Â ° C in Vostok.
The highest temperatures ever recorded in Antarctica are 17.5 ° C (63.5 ° F) at Esperanza Base, on the Antarctic Peninsula, on March 24, 2015. The average annual temperature of the interior is -57,, Â ° C (-70.6 Ã, Â ° F). The coast is warmer. Monthly means at McMurdo Station range from -26 Â ° C (-14.8 Â ° F) in August to -3 Â ° C (26.6 Â ° F) in January. At the South Pole, the highest temperature ever recorded was -12.3 Â ° C (9.9 Â ° F) on 25 December 2011. Along the Antarctic Peninsula, temperatures as high as 15 Â ° C (59 Â ° F) have been recorded, though summer temperatures below 0 Ã, Â ° C (32Ã, Â ° F) most of the time. Severe low temperatures vary with latitude, altitude, and distance from the ocean. East Antarctica is colder than West Antarctica because of its higher elevation. The Antarctic Peninsula has the most moderate climate. Higher temperatures occurred in January along the coast and averaged slightly below freezing.
Maps Climate of Antarctica
Precipitation
The total rainfall in Antarctica, on average across the continent, is about 166 millimeters (6.5 inches) per year (Vaughan et al., J Climate, 1999). The actual rate varies greatly, from the high value in the Peninsula (15 to 25 inches per year) to very low values ​​(at least 50 millimeters (2.0 inches) in high interiors (Bromwich, Review of Geophysics, 1988). millimeters (9.8 inches) of rainfall per year is classified as a desert Almost all Antarctic rainfall falls like snow Rainfall is rare and mainly occurs during summer in coastal areas and surrounding islands Notice that the quoted rainfall is the size its equivalence to water, rather than the actual depth of snow, the air in the Antarctic is also very dry, low temperatures produce very low absolute moisture, which means that dry skin and chapped lips are a constant problem for scientists and expeditions working in the continent.
Classification of weather conditions
Weather in Antarctica can vary greatly, and weather conditions can often change dramatically in a short time. There are various classifications to describe weather conditions in Antarctica; restrictions granted to workers during different conditions vary by station and country. In Antarctica, there are various stations scattered everywhere in Antarctica, 16 in Antarctica total (Amery, Burger Hills, Cape Poinsett, Casey, Davis, Dumont D'urville, Haupt Nunatak, Law Dome, Mawson, McMurdo, Mirnyj, Novolazarevskaja , Skiway South, Syowa, Whoop Whoop and Wilkins Runway) and one in the sub-Antarctic (Macquarie Island). The three places that have the lowest temperatures are Amery, Law Dome and Wilkins Runway (temperature in the order of: -24.1, -12.8, -10.2).
Ice cover
Almost all Antarctica is covered by a sheet of ice, on average, one mile thick or more (1.6 km). Antarctica contains 90% of the world's ice and more than 70% fresh water. If all the ice sheets covering Antarctica are melting - about 30 million cubic kilometers (7.2 million cubic miles) of ice - the ocean will rise more than 60 meters (200 feet). However, this is highly unlikely in the next few centuries. Antarctica is so cold that even with a few degree increase, the temperature will generally stay below the melting point of ice. Higher temperatures are expected to cause more snow, which will increase the amount of ice in Antarctica, offsetting about a third of the estimated sea level rise from the ocean's thermal expansion. Over the past decade, East Antarctica has thickened at an average rate of about 1.8 centimeters per year while West Antarctica shows an overall depletion of 0.9 centimeters per year. For Antarctic contributions to present and future sea level changes, see sea level rise. Because the ice flows, albeit slowly, the ice inside the ice sheet is younger than the age of the sheet itself.
Ice shelves
About 75% of Antarctic coastlines are ice shelves. The topmost part consists of ice floating until the glacier ground line by ground is reached, which is determined through affords such as IceBridge Operation. Ice shelves lose mass through the breaking of the iceberg (calving), or basal melting (at the foot of the glacier, when the impacts of warm ocean water), and this may affect the stability of the ice sheets when the land-based glaciers begin to retreat; melting or breaking of floating ice blocks does not directly affect global sea level, but, when the sea ice freezes, it is preferable to dispose of salt, in the process of becoming purer than the seawater it floats in. Pure water is less dense than saltwater, so when the ice melts it will overflow the 'hole in the water' that has been occupied by ice, and when it overflows, it raises the water level.
Known changes in coastline ice:
- Around the Antarctic Peninsula:
- 1936-1989: Wordie Ice Shelf is greatly reduced in size.
- 1995: Ice on Prince Gustav Channel destroyed.
- Parts of the Larsen Ice Shelf have broken out in recent decades.
- 1995: Larsen A ice shelf was destroyed in January 1995.
- 2001: 3,250 square kilometers (1,250 square miles) from the Larsen B ice shelf was destroyed in February 2001. Gradually retreat before the break event.
- 2015: A study concludes that the rest of the Larsen B ice shelf will be destroyed by the end of the decade, based on faster flow observations and rapid glacier depletion in the area.
The George VI Ice Shelf, which may be on the brink of instability, may have existed for about 8,000 years, after melting 1,500 years earlier. The warm ocean currents may be the cause of the melting. Not only the ice layer loses mass, but they lose mass at the rate of acceleration.
Global warming
The average surface temperature trends of the Antarctic continent are positive and significant at & gt; 0.05 Â ° C/decade since 1957. The West Antarctic ice sheet has warmed over 0.1 Â ° C/decade in the last 50 years, and is strongest in winter and spring. Although this is partially offset by the cooling decline in East Antarctica, this effect was limited in the 1980s and 1990s.
Research published in 2009 found that the entire continent has become warmer since the 1950s, a finding that is consistent with the effects of man-made climate change:
The British Antarctic Survey, which has undertaken most of Britain's scientific research in the area, stated in 2009:
- The loss of ice in West Antarctica can lead to a 1.4 meter (4 feet 7 inch) sea level rise
- Antarctica is predicted to warm about 3Ã, Â ° C (5.4Ã, Â ° F) during this century
- 10% increase in sea ice around Antarctica
- Fast ice loss in some parts of Antarctica
- Southern Ocean heating will cause an Antarctic ecosystem change
- Holes in the ozone layer, which has protected most of Antarctica from global warming
The strongest cooling area appears at the South Pole, and the strongest heating region lies along the Antarctic Peninsula. A possible explanation is the loss of ozone absorbing UV may cool the stratosphere and reinforce the polar vortex, the wind pattern that revolves around the South Pole. The whirls act like atmospheric barriers, preventing warm, beach air from moving to the interior of the continent. A stronger polar vortex may explain the cooling trend in the interior of Antarctica.
In their latest research (September 20, 2007) NASA researchers have confirmed that Antarctic snow melts further into the mainland from the coast at all times, melting at higher altitudes than before and increasingly melting in the largest Antarctic ice sheet.
There is also evidence for glaciers that are widespread around the Antarctic Peninsula.
The researchers report on Dec. 21, 2012 in Nature Geoscience that from 1958 to 2010, the average temperature at Byrd by-mile-high stations rose 2.4Ã, Â ° C (4.3Ã, Â ° F), with the fastest heating in season cold and spring. The place in the heart of the West Antarctic Ice Shelf is one of the fastest warming spots on Earth. By 2015, temperatures show changes but are stable and the only months that have drastically changed in that year are August and September. It also shows that the temperature is very stable throughout the year.
Increasing Antarctic Temperature
The World Meteorological Organization Committee of experts has announced a new evaluation result involving the highest temperatures recorded on the Antarctic continent as part of ongoing efforts to maintain the accuracy of extreme weather databases and climatic conditions worldwide.
It upholds the existing record of 17.5 Â ° C (63.5 Â ° F) recorded on March 24, 2015 at the Argentine Research Base Esperanza, located near the northern tip of the Antarctic Peninsula.
On March 23, 2015, an automatic weather station established by the Czech Republic at Davies Dome, also near the northern tip of the Antarctic peninsula, recorded a temperature of 17.9 ° C (64.2 ° F). As a result, the polar meteorological panel carefully examines the data involved with Davies Dome's observations to determine if it has set a new record.
See also
- Antarctica cools controversy
- Global warming in Antarctica
- Arctic Climate
- The effects of global warming
- Glacier retreat since 1850
- Polar Amplification
References
Note
Source of the article : Wikipedia
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