Antarctica occupies most of the climate zone. Climatic conditions of Antarctica. What to do in the warmest month in Antarctica and in the Arctic

One of the reasons for the severity of the climate of Antarctica is its height (the most high mainland on the planet) . As you know, with height, the air temperature at the Earth's surface drops by an average of 0.6 ° C for every 100 m of elevation. In this regard, Antarctica should be colder than any continent by 6-7 °C. However, the root cause of glaciation is not height, but geographical position circumpolar sixth continent: the farther from the equator to the pole, the less solar heat a unit of the Earth's surface receives due to the greater inclination sun rays. An additional reason for the cooling is the fact that land is located around the pole, and not the ocean. The ground absorbs 70% of solar radiation, and the ocean absorbs more than 90%. The snow-ice surface of Antarctica absorbs only 10-20% of solar radiation; It reflects 90% of the sun's rays like a giant mirror into the world space.

A very cold air column is formed above the glacial surface of Antarctica, in which the temperature does not fall with height, but increases, i.e. there is a temperature inversion (unlike all other continents of the Earth). Heavy cold air from the central regions of the mainland spreads in all directions along the slopes of the ice sheet, forming a katabatic wind. The loss of air above the center of the continent is replenished by the inflow of new air masses from higher layers of the atmosphere. Air masses from adjacent latitudes enter the high layers. A downward circulation is created, a typical anticyclonic process, which is accompanied by air drying. The absence of cloudiness contributes to further cooling of the mainland. Those 10% of solar energy that is absorbed by the surface of Antarctica also mostly goes into space. Like any body heated above absolute zero, snow radiates heat in the form of infrared waves. Since there are no clouds over the central regions of Antarctica, this long wavelength radiation escapes freely into space.

According to the nature of the climate in Antarctica, the following are distinguished: the inland alpine region, the glacial slope and the coastal zone. The glacial plateau is characterized by extreme frosts, a polar anticyclone, the predominance of clear weather, and a small amount of precipitation falling all year round in the form of snow (30-50 mm/year). Here is the center of the continent - the Pole of relative inaccessibility. The circumpolar zone of glacial slopes, along which the paths of glacial runoff fan out from the high mountain ranges, has a width of 700-800 km. Average monthly temperatures in the zone range from 50°С in winter to 30°С in summer months. Low temperatures are combined with constant winds blowing from high mountain ranges, and snowstorms. Precipitation in the form of snow falls 100-250 mm/year. The narrow coastal zone receives up to 700 mm of precipitation, mainly in the form of snow. In winter, average monthly temperatures range from 8 to -35°C, in summer - from 0 to + 2°C. The usual wind speed is 50-60 m/s.

Antarctica is the coldest place on earth. The climate of Antarctica is unique, it is characterized by the lowest temperatures and abnormal natural phenomena. Precipitation, wind speed and nebula vary as you approach the coastline.

Weather in Antarctica in winter is extremely aggressive, the temperature reaches -80 °C, and in summer near the coast the temperature is about +5 °C.

Surprisingly, for many mainlanders, sunburn is a big problem, because the snow reflects the sun like foil. Another problem in the summer is increased solar radiation.

Weather in Antarctica in summer(December-February) is much milder than winter, so tourists are advised to visit the mainland at this time of the year. It is sunny in Antarctica in summer, there are much less winds, the highest temperature in summer was recorded in the Mirny settlement in January +30 °C.

The strongest winds formed on the slopes have a thickness of 200-300 m, raising snow dust, practically depriving visibility.

The climate of any place on earth, as well as climate of Antarctica, is formed under the influence of three main factors: solar radiation, atmospheric circulation and geographical conditions of the place itself. Mainland Antarctica.

Mainland Antarctica

It is known that where the earth receives a lot of solar heat, as, for example, at the equator, it is always hot; where air currents bring moist sea air, it is damp; on the top high mountain it is cold and snowy, and at its foot stands eternal summer. But there are places on Earth, and even a whole continent, where in summer almost as much solar heat falls on its surface as in the subtropics. However, here not only grapes do not ripen, but even grass does not grow. The ground is covered with a thick layer of snow and ice that does not melt even in summer. This is what it is mainland Antarctica. On a clear summer day on the coast, each square centimeter of the surface receives about 0.5 calories of solar heat per minute. The amount of incoming heat in one summer month is almost 20,000 calories (20 large calories). This is one and a half, even two times more than at the same latitudes of the northern hemisphere, and only slightly less than what the cotton fields near Tashkent receive. If all this heat were spent here on melting, then in one summer its power would decrease by ten meters, i.e., in 10-15 years in the region Mirny(located on the coast of Antarctica) the ice would have completely melted.
Glacier on the coast of Antarctica. In the depths of the mainland, for example, at the station Pioneer, even more solar heat enters the snow surface in summer, but the snow does not melt. Eternal frost and blizzard reign here. Why is this happening? Where does all this huge amount of solar energy go? After all, according to the law of conservation of energy, it should not disappear anywhere!..

The mystery of the climate of Antarctica

It was the main climate mystery of Antarctica. To unravel it, the members of the first Soviet Antarctic expedition, which was based at Mirny and Pionerskaya stations, continuously monitored the inflow and outflow of solar heat throughout the year, that is, they kept a kind of "accounting" of solar radiation. Most of this work was carried out by special self-recording devices - "electromechanical" accountants of the Sun ". They continuously recorded how much heat comes from the sun, how much it is reflected and radiated by the snow-ice surface of Antarctica, and, finally, what kind of radiation balance is obtained.

Climate research in Antarctica

results climate research in Antarctica exceeded all expectations. It turned out that about 80-82% of the sun's rays falling on it are reflected from the snow-ice surface of Antarctica, like from a mirror, in winter and summer. This huge amount of solar energy almost completely goes back into space.
Snow and ice climate of Antarctica. Well, where do the remaining 18-20% of the sun's rays that fall on the ground go? They are absorbed earth's surface and turn into heat. But even this already assimilated heat cannot be saved by the surface of Antarctica. Almost half of it (more than 10% of the total radiation) is lost by thermal radiation, and only the remaining 8-10%, and on Pionerskaya even 5%, Antarctica spends for its needs. But it happens in the summer(from November to February). in winter(from March to October) the surface of Antarctica receives almost no solar heat at all. And the radiation of heat from its surface occurs continuously. Heat loss every month due to radiation in winter is 2-3 large calories. Calculations show that due to radiation, the surface of Antarctica would cool by about 5-6 ° per hour. However, this does not happen. Only once, while exploring the climate of Antarctica, did the members of the first expedition, which arrived in Antarctica in January 1956, witness such a sharp drop in temperature. It was August 20 - in the middle of the harshest month of winter. The sewage wind (the wind flowing from the snowy peaks of the mainland), which usually begins in the evening, suddenly subsided. It quickly cleared up, and the temperature dropped by 10° within an hour and a half, reaching -40.4°. It was the lowest temperature in Mirny. Then the wind blew and again it became warmer on the southernmost land.

Influence of air circulation on the climate of Antarctica

So the movement air circulation saves the surface of Antarctica from continuous cooling. The influence of atmospheric circulation on the formation of the climate of Antarctica is unusually great. In Mirny, for example, there was not a single winter month in which the air temperature did not rise to -3 -6 ° with the arrival of the sea air mass. So, for example, from 29 to 30 April of the year under study, during the day the temperature increased from -25 to -8°. Such warming spread even to Pionerskaya, where during the same day the temperature increased from -50° to -30°. Warm periods in winter in Antarctica sometimes last a week or more. The transfer of heat from the air to the underlying surface in this case occurs not only by air vortices, but also by thermal radiation of the atmosphere. The surface of Antarctica, instead of radiating heat, begins to receive it from the atmosphere, the radiation balance becomes positive and the temperature begins to rise rapidly. Due to the circulation of the atmosphere, not only heat, but also cold is brought to the shores of Antarctica. This happens when the air does not move from the sea, but from the depths of Antarctica, flowing down the slope of the Antarctic Plateau.
The cold off the coast of Antarctica is not a hindrance to penguin hunting. Just as water, after a heavy rain that has fallen on a mountainside, flows down to the foot, rapidly accelerating its movement under the influence of gravity, so cooled, denser air descends along the long slope of the glacial plateau of Antarctica. It moves faster and faster every minute, often reaching the strength of a hurricane near the coast. However, unlike the flow of water, the air flowing down the slope is continuously heated (for every 100 m of height by 1 °), so the temperature with which it comes to the coast, although low, is much higher than that which would be here if there would be no wind. This is confirmed by data from remote stations. So, for example, on a clear day on August 12, when a storm was raging in Mirny, 13 km away on fast ice (this is the name of the ice above the surface of the water, firmly fused with the continental ice), where the influence of the sewage wind did not affect, there was calm and temperature air was 11° lower than in Mirny. Waste wind in Antarctica is a "cold" hair dryer. The air, moving from the central regions of Antarctica, as well as with an ordinary hair dryer, heats up and, moving away from the saturation point, becomes drier. However, due to relatively low altitudes and very low initial temperatures, it cannot get very hot, so it comes to the coast not warm, but cold. For example, such a case: the air moves from Pionerskaya station to Mirny. The height difference between these stations is about 3 km. If the air temperature on Pionerskaya was -50°, then it will come to Mirny with a temperature of -20°, i.e., still very cold. The circulation of the atmosphere over Antarctica is completely peculiar. In coastal areas, and even far inland, the winds blow from almost one sector all year round (from north-northeast to south-southeast), but depending on whether they blow closer to the eastern edge of the sector or to south, the weather changes very sharply. East winds are associated with the movement of the cyclone and carry heat, while southeast winds are associated with the flow of cold inland air and carry cold.

Influence of terrain on the climate of Antarctica

On the climate of Antarctica affects and terrain influence. Here, in one area, a severe storm with a blizzard and calm weather can be observed simultaneously, although there are no big differences in the relief at all. This is how the participants of the expedition describe the trip to Mirny.

In early August, we had to go to the inspection station at one of the remote stations, 4 km from Mirny, and, like Mirny, located not far from the coast. The weather was clear, a weak southeast wind (5 m/s) was blowing. Having left the transmitting radio station, we saw ahead, as it were, a veil of fog, which thickened and rose as we approached the sea. A few minutes later the all-terrain vehicle drove into the strip of snow. Thousands of small streams moved near the surface of the ice, merging into separate streams. The farther we moved, the streams became denser, as if clinging to one another, until they merged into a huge milky white river. And now we are crossing the "river" ford. The level of the blizzard is getting higher, soon it closes the tracks of the all-terrain vehicle, and then the windshield. You have to drive blindly. In order not to go astray, we get out on the cabin. The station is not visible, only the State Flag fluttering on the mast is visible. When we arrived at the station and got out of the car, it was impossible to walk, our feet slipped on the ice polished by blizzards, and the wind instantly knocked us down. There was a storm here. The wind speed was three times stronger than in Mirny. And at the station, located on fast ice, at that time it was quite quiet. Free from watch people went skiing. A nearby colony of emperor penguins has begun to hatch chicks.

The influence of the terrain especially affects the temperature regime. For example, unusually low temperatures at Pionerskaya station (69°44" S), located at an altitude of about 3 km, are striking. The average annual air temperature at this station is below 38°. Interestingly, at approximately the same latitude, but in the northern hemisphere of Kola station (near Murmansk, 68°53"N), the average annual air temperature is -5°. At Pionerskaya station the highest temperature was -13°C, and at Kola station +32°C. Many such examples could be cited.

The climate of Antarctica depends on the rarefied air

severity Climate of Antarctica, especially in inland regions, is also exacerbated rarefied air caused by high altitudes above sea level.
Harsh climate of Antarctica. At Pionerskaya station, for example, the air pressure is one and a half times lower than at Mirny. With such pressure, any rapid movement disrupts the rhythm of breathing, a person quickly gets tired even from a slight physical exertion. Undressing before going to bed, sitting on a bunk, and then climbing into a sleeping bag, caused the same heartbeat as after a long and fast run. It is especially difficult in such conditions to perform heavy physical work. There was such a case during the expedition.

Immediately after arriving at Pionerskaya, they had to dig a room in the dense snow to extract hydrogen, which was necessary for the production of pilot balloons and radiosondes. It was possible to dig a room with a bulldozer, but how to make a roof? At hand, except for a few fragile rails and two or three drill pipes, there was nothing. Having laid them as a ceiling, they began to cover the room with a tarpaulin. The roof was fragile, but held. We proceeded to the equipment of the gas generator. We finished the work at 2 am (it was a round-the-clock spring day). After a short rest, we decided to start producing hydrogen. What a disappointment it was when, having come to the gas generator, they saw that a huge snowstorm had blown up on the roof. The roofs have caved in. Climbing into the room was dangerous. Soon all this mass of snow collapsed, filling up all the equipment. The snow had to be thrown out by hand, as the bulldozer could break the instruments. This is where the low pressure comes into play. Throwing each shovel of snow to a height of 2-2.5 m caused shortness of breath. After making several throws, people fell down. And then there was the continuous blizzard, nullifying the results of all the labors. To make reliable ceilings, it was necessary to dismantle the flooring of the only tractor sledges at the station. But the sleigh was far away. The tractor didn't work. The boards had to be torn off the sled and carried on oneself. They walked slowly, carrying two boards. Here, throwing the boards aside, the radio operator Ushakov fell into the snow. He was carrying three planks, and his breath caught. Having thrown off the boards, each of us, even Zotov, who squeezed more than 90 kg on the dynamometer with one hand, stopped exhausted or lay down on the snow under a prickly snowstorm. But what was the joy when a few days later, for the first time in the history of science, a radiosonde rose in the depths of Antarctica. A regular study of the high layers of the atmosphere inside the ice kingdom began in order to study more thoroughly the climate of Antarctica.

These were the main patterns of formation of the climate of Antarctica, these are the main reasons for its severity. But the influence of the atmosphere on the climate of Antarctica was not the only mystery, and was not limited to climate issues. Before the eyes of researchers, such phenomena arose that even the venerable scientists of the world could not answer. Many of these phenomena have not even been observed before. For example: "disappearance of the stratosphere", snow tornadoes (blood clots); colored halos and false suns, a winter rainbow arched backwards; haze over snow, haze of snow (fog); ice cloud near the ground; colored drifting snow, snow fountains-geysers, summer clouds in the depths of Antarctica, a whitening effect, sparks flying from the hands, a neon light bulb that lights up at the touch of a finger, and much more. Each of these phenomena is observed at a certain time of the year, therefore, in order to unravel them, one must at least mentally imagine these conditions.

Causes of the harsh climate of Antarctica

Remark 1

Antarctica is a continent of harsh climatic conditions, hurricane-force winds, endless expanses of ice and low temperatures, the climate of which depends primarily on its geographical location.

This highest continent is located at an altitude of 2000 m above sea level, and its central part reaches 4000 m.

Figure 1. Climate conditions in Antarctica. Author24 - online exchange of student papers

Most of the height falls on a permanent ice sheet that hides the continental relief.

The climatic features of the mainland are associated with a large amount of incoming solar energy, and at the same time with low temperatures.

The lowest temperature mark was recorded at the Vostok station and amounted to -89.2 degrees - the station is the absolute cold pole of the Southern Hemisphere.

With the advent of the summer period, the air temperature rises to -30, -20 degrees. On the coast, it is much warmer than 0 degrees, and sometimes even higher.

Despite the fact that in summer the mainland receives a large number of heat, about 80-82% is reflected from the snow-ice surface and goes back. The remaining amount of heat is absorbed by the surface and converted into heat, but half of it is lost by thermal radiation.

In winter, the mainland does not receive solar heat at all, while heat radiation from its surface occurs continuously and the surface cools even more.

Another reason for the severity of the Antarctic climate is katabatic winds, which are formed as a result of the temperature difference between the surface of Antarctica and air, as well as its dome-shaped configuration.

Such winds blow almost without interruption from April to November.

The terrain also has its influence on the climate, although there are no big differences in the relief, but in one area there can be a strong storm with a snowstorm and calm at the same time.

The circulation of the atmosphere over Antarctica is very peculiar. All year round in the depths of the mainland and in coastal areas, winds blow from one sector - from the north-northeast to the south-southeast.

True, if they blow closer to one edge, for example, to the south or east, then the weather changes very dramatically.

Due to the circulation of the atmosphere, both heat and cold are brought in, and this happens when air moves from the depths of the mainland, flowing down the slope of the Antarctic plateau.

East winds carrying heat are associated with the movement of the cyclone, and southeast winds are associated with the runoff of inland cold air.

Another reason that affects the climate of the mainland is the rarefaction of the air, since the height above sea level is significant. Especially rarefied air affects the severity of the climate in the interior.

Climate of Antarctica

The mainland lies in two climatic zones - subantarctic and antarctic.

The northern tip of the Antarctic Peninsula is sometimes referred to as temperate zone. Within it there is no polar day and nights, but despite this, the conditions of the peninsula are very harsh.

On its coast, the average annual temperatures-10 degrees. At its northern tip, the air temperature rises to -5 degrees.

In the northwestern part of the peninsula, in coastal oases, the January average temperature above zero and is +1, +2 degrees.

Positive temperatures here can be observed at any time of the year.

Twenty-degree winter frosts may be replaced by thaws. The maximum temperature of +14 degrees recorded here was observed at the height of winter - in July on the east coast in 1958.

On the northwestern coast of the peninsula, precipitation is 700-800 mm, and sometimes even up to 1000 mm. On average, about 120 mm falls on the mainland per year, in the depths of the continent their number decreases and only 30-50 mm falls per year.

In the inland regions of Antarctica, the most harsh conditions. The winter temperature here drops to -64 degrees, and the summer temperature rises to -32 degrees.

In the depths of the continent are formed strong winds, the speed of which reaches 80-90 m/s. Reaching the coast, the wind intensifies.

Around Antarctica, intense cyclonic activity develops over the ocean.

In the west of the mainland coastline well indented and there are bays that go far into the land, it is here that cyclones penetrate the mainland. Their penetration to the east of the mainland is rare.

The Antarctic coast is an area where the climate is moderately humid and relatively mild. In summer, the thermometer sometimes rises above zero, and the snow begins to melt intensively.

On the coast of Antarctica, the air is noticeably warmer, here the warming effect of the ocean affects. Despite the fact that coastal waters are covered with ice and have a temperature close to the freezing point, the water is warmer than air and is constantly exchanging heat with it.

The temperature on the coast does not fall below -40, -45 degrees, and the average annual temperatures are -10, -12 degrees.

The temperature of the coast in summer is -4 degrees. Stock winds here reach speeds of 15-20 m/s. With katabatic winds, clearings are observed.

In summer, sunny weather on the coast of the mainland contrasts sharply with gloomy clouds over the ocean. Up to 500 mm of precipitation falls on the eastern coast, and up to 700 mm on the western coast.

The most severe conditions have formed in the inland regions of Antarctica.

Inland climate

In the inland regions of Antarctica, climatic conditions are the most severe on the planet.

Regular meteorological observations are carried out here at the Amundsen-Scott and Vostok scientific stations. At Fuji Dome Station, a minimum temperature of -91.2 degrees was recorded.

The average winter air temperature is -60, -70 degrees, the summer temperature rises to -45, -25 degrees.

The Amundsen-Scott station was founded at the South Pole in 1956 and is gradually drifting towards the coast. This is due to the fact that the glacier slowly slides from the dome-shaped mainland from the center to the edge, where it breaks off under its own weight and enters the ocean.

At this station in winter, the thermometer reaches -60 degrees, and in January it does not fall below -30 degrees.

The climate at the Amundsen-Scott station is slightly milder compared to the Vostok station.

Figure 2. Inland climate. Author24 - online exchange of student papers

The inland Vostok station has existed here since December 1957, and during the entire existence of the station, the thermometer showed -13.6 degrees only once - it was the warmest day, December 16.

Such a high temperature was associated with the invasion of cyclones from the ocean to the mainland, which is extremely rare.

The minimum temperature from April to September at Vostok station is below -80 degrees, and the average monthly temperature is below -70 degrees. But, in mid-April and at the beginning of the third decade of September, it is above -70 degrees.

Winter temperature fluctuations are less than summer ones.

Remark 2

Thus, the lowest absolute minimum air temperatures are observed at the stations:

• "Pole of Inaccessibility"
• "Kun-Lun"
• "East",
• "Vostok-1",
• Fuji Dome.

In the central regions of Antarctica, a very small amount of precipitation falls during the year, which is common feature climate of this region.

Precipitation comes in the form of "diamond dust" - these are ice needles, as well as frost. The wind speed here is small, increasing with approach to the continental slope.

The climate of the Antarctic continent for several millennia has firmly held the palm in some respects. Nowhere else on Earth is such a constant low temperature throughout the year, and nowhere else do water and air temperatures drop to such a low level.

A decisive role in shaping both the climate of Antarctica itself and the climate of most of the Southern Hemisphere is played by the ice shell covering the southern mainland. This shell, called continental glaciation by scientists, is the world's largest source of cold. The ice surface of the Antarctic continent has a colossal reflective power. During the long polar day, the total solar radiation over the Antarctic approaches the equatorial level, but almost 9/10 of it is reflected back into the atmosphere. In winter, night reigns over the Antarctic for several months, and the southern polar region receives practically no solar radiation.

Above the Antarctic waters, where the cyclonic weather regime prevails, and the sky is almost constantly covered by low lead clouds, the values ​​of incoming solar radiation are 2-3 times less than over the continent. The fiftieth-sixtieth latitudes of the Southern Ocean, in contrast to the Antarctic continent, are the zone of minimum the globe amount of solar radiation. Every time newcomers arrive in Antarctica after their first hours of work under the Antarctic sun, the faces of newcomers are burned and often, if protective measures are not taken, they receive severe sunburn.

However, such a high intensity of solar radiation is observed only during the short period of the Antarctic summer. In winter, it drops to zero. Nevertheless, in general, for the year, Antarctica receives amounts of solar radiation comparable to the values ​​typical, for example, for our Black Sea resorts. But no matter how great the influx of solar energy, over 80% of it is reflected by the snow surface and escapes into outer space.

The radiation balance of the ice surface, i.e. the ratio of incoming and outgoing radiation in Antarctica is always negative - except for two or three months a year. If not for the influx of relatively warm air masses from the ocean, Antarctica would be a progressively self-cooling refrigerator.

Isotherms - lines of equal air temperatures - are located on the surface of the Antarctic continent in concentric circles with a center in the region of the so-called pole of relative inaccessibility. Here, in summer, the average monthly temperatures fluctuate around minus 36 °C, while in winter they reach 72 °C below zero. Central Antarctica is the coldest region not only of the entire continent, but of the entire Earth. From this cool high inland plateau there is a gradual increase in temperature in all directions.

Coastal regions, where the heights are not high, and the warming effect of the sea, in contrast to the central regions, are the warmest in Antarctica. In Mirny, the average monthly temperature of the warmest month - December - is 2 °С below zero, and in winter - in July - minus 18 °С. Compared to Central Antarctica, the difference is huge, but it is characteristic that even here the average temperature of even the warmest month remains below zero. The only exception is Northern part Antarctic Peninsula, whose oceanic climate is not typical for the main part of the mainland.

True, at the height of summer on the coast almost everywhere, and especially where rocks are common, air temperatures often rise above zero. In the same Mirny, maximums up to 8 °C above zero were noted. But such phenomena are short-lived and, moreover, cover only a narrow coastal zone. So, in general, the Antarctic continent can be considered as an area of ​​constant negative air temperatures. This is also evidenced by the fact that in Antarctica all precipitation falls only in solid form. Antarctica is the only continent where it does not rain (again, the exception is the northern part of the Antarctic Peninsula).

Distribution precipitation over the territory of the continent, as well as in the case of temperature, zonal-concentric. The central intracontinental regions receive a minimum of precipitation - from 40-50 to 80-100 mm per year. Such values ​​are typical only for the Sahara, so Central Antarctica can be called the world's dryness pole. A desert in the area of ​​​​the highest concentrations (albeit in solid form) of fresh water on land ... This is another paradox of the sixth continent.

On the coast, up to 500-600 mm of precipitation falls annually, and even more in some parts of the slope of the Antarctic cover. Winds prevailing in the slope zone lead to some redistribution of the amount of deposited snow. In general, according to calculations, about 2340 km3 of water per year accumulates over the entire area of ​​the Antarctic continent, which corresponds to an average layer of 175 mm of precipitation.

Warms Antarctica, if applicable to southern mainland such a concept, basically warm air brought by winds from the ocean. The closer to the coast, the more heat gets to the earth from cyclones formed over the Southern Ocean. In the central part of Antarctica, on the glacial plateau, the process of freezing out moisture occurs with the mixing of horizontal layers of air, and precipitation here falls in the form of ice needles and hoarfrost. clear sky; apparently, this explains the dryness of the air flowing from the central plateau of the continent to the coast. On the coast and on the slopes of the ice sheet, a significant proportion of precipitation is brought by oceanic cyclones, and they fall in the form of snow. The thickness of the snow layer falling annually in the central part of Antarctica is only 10-20 cm, on the glacial slope and near the coast - 150-200 cm. It does not rain over most of Antarctica; extremely rare, not more than once in several years, they are observed at coastal stations. But over the Southern Ocean, the air is very humid, the sky is mostly covered with clouds, and here precipitation, as a rule, falls in the form of rain and sleet.

The contact of ice massifs with relatively warm oceanic waters creates conditions for enhanced circulation of air masses throughout the year. Above the ice massif of Antarctica is the so-called Antarctic maximum, associated with a constant strong cooling of the air above the surface of the glacier. Cold air streams flow down from the high glacial plateaus of Central Antarctica, forming the strongest southeasterly winds, known to us as katabatic winds, on the outskirts of the continent, and weak easterly winds prevail along the edge of the maximum region. Above the ocean, near the mainland, there is a zone of relatively low pressure and cyclones, in which the most important are westerly winds. Pressure distribution in upper layers atmosphere causes an influx of warm, moist air from the ocean to the mainland, which, in turn, causes precipitation over Antarctica, which feeds glaciation.

In the inner parts of the Antarctic continent, as well as in its eastern part, in summer there is mostly clear sunny weather with very low temperatures. This combination of weather conditions is typical for areas of anticyclones and high atmospheric pressure, which, in fact, is Central Antarctica. At the Russian Vostok station, a temperature of 88.3 °C below zero was recorded. Average August temperatures in Antarctica fluctuate around 52°C below zero, while average January temperatures in some parts of the continent remain below the 20-degree mark. In the summer months in Antarctica, temperature increases up to 3-4 °C above zero are possible, associated with sunny weather. In those years when the outskirts of the mainland fall under the influence of oceanic cyclones in summer, summer, as a rule, is marked by cooling and snowfall. In general, the oceanic ring near the coasts of Antarctica is noticeably colder in summer than the coastal regions of the mainland itself, and warmer in winter.

The Antarctic oases are characterized natural conditions dry cold desert. In summer, the surface of the earth, free from snow and ice, warms up to some extent, and at a height of several tens of centimeters above the ground, the air temperature is quite high. Of course, its significance also depends on the nature of the surface itself; Thus, on the rocks near the Russian scientific settlement Mirny at the height of the Antarctic summer - in January - temperatures of about 30 ° C above zero were more than once noted. However, already at a height of 1-2 m above the ground, the air is not much warmer than over the nearby ice. On a summer day, cumulus clouds can form over the oasis, generated by ascending air currents. Descending dry winds coming from the glaciers create conditions for the evaporation of moisture and drying up the surface of the earth. In winter, the oases are covered with snow.

During the southern polar night, the difference in climatic conditions between the oases and the glacial surface is minimal. It becomes more noticeable and tangible as soon as the sun appears. This can be explained, first of all, by the completely different reaction of various surfaces to solar radiation fluxes. If snow and ice, as already mentioned, reflect the main - up to 85% - part of the incident radiation, then rocks painted by nature in darker colors, on the contrary, absorb about 85% of solar radiation, heating up to 20-30 ° C, and As a result, they heat up the surrounding air. Thus, any appreciable share of solar energy, which is more than abundant in Antarctica, is assimilated only in oases.

Snow melting in summer occurs only in a narrow coastal zone. Under the influence of intense solar radiation, the snow becomes loose, and streams run from the coast into the ocean, but already at a distance of 10-12 km from the coast, snow melting is imperceptible. Only on the surface of the snow in summer a thin "radiation" crust of ice is formed, similar to crust. But on the slopes of the dark rocks facing the sun, the reflectivity of which is relatively small, the snow melts intensively even in areas remote from the coast.

The natural conditions of the Antarctic and subantarctic islands, in contrast to the conditions of the mainland itself, are not so severe. But even on the islands, before many others natural phenomena strong westerly winds prevail, the speed of which sometimes reaches 75 m / s. These winds owe the Subantarctic the appearance of the name - "furious fiftieth latitudes."

On the subantarctic islands, a lot of precipitation falls, and, unlike Antarctica proper, here they relatively often take the form of sleet, sometimes turning into drizzling rain. Summer temperatures in the belt of islands rarely exceed 10 ° C above zero, while winter ones fluctuate around the zero mark of the scale.

open water streams there are practically none in Antarctica, they are replaced by rare under-ice streams, not all of which flow into the sea. In the summer months, on the outskirts of the mainland, you can find small reservoirs with stagnant water, in oases - salt and fresh lakes. As a rule, these are endorheic reservoirs, only a few of them have a drain into the sea. Some lakes appear only when snow melts in oases - they subsequently dry up quickly, leaving salt spots on the soil. On the winter months all reservoirs freeze, but in summer the water temperature in the lakes of the oases is much higher than the air temperature.