The coldest month in Antarctica. Climatic conditions of Antarctica. Influence of terrain on the climate of Antarctica
The climate of the Arctic and Antarctica is in many ways similar - in its severity and extreme environmental conditions. We will talk about the second of the polar regions today. The climate of Antarctica can be briefly described as the most severe on the entire globe. This is due to the peculiarities of the position of the mainland relative to the surface of the planet. In addition to a small area of the northern part of the peninsula, the territory of the continent is located in the Antarctic zone.
Perhaps the southernmost of the earth's continents is the most mysterious place on the entire planet. Its ice-bound expanses are in no hurry to reveal their natural secrets to man. In the extremely cold climate of Antarctica, brave researchers work at special scientific stations located there.
According to scientists, an area of 13,661,000 square kilometers of the continent is covered with ice. The South Pole of our planet lies in the Antarctic region. Its territory does not belong to any of the states. According to international treaties, it is forbidden to develop minerals on it. Only research and scientific activities are allowed.
Climate in Antarctica in antiquity
In the deep past, the Antarctic plate was characterized by less severe weather compared to modern geological time. Nowadays, it is almost impossible to find temperatures above 0⁰С on the mainland. In the Mesozoic era, during the split of the ancient land of Pangea into separate parts, the globe had a milder climate. The mainland of Antarctica in that era was located closer to the equator (that is, to the north). Its surface was covered with tropical forests.
Millions of years later, in the process of moving the plates of the earth's crust of the mainland, the Antarctic plate shifted to the subpolar region.
This movement of a section of the earth's crust to the south led to the formation of an ice sheet on land, which became the main cause of a decrease in temperature throughout the planet. Temperature changes were especially evident in the Southern Hemisphere.
By the time the Antarctic plate moved to the polar region, the surface of the planet had undergone important changes, the essence of which was the closure of the ancient Tethys ocean, the formation of a land isthmus between the plates that make up the territories of the current South and North Americas, and the formation of a circular cold polar current around the Antarctic continent.
The warm conditions of terrestrial weather disappeared, the polar and circumpolar regions were subjected to glaciation. They formed desert regions with harsh and arid weather conditions.
Climate zones of Antarctica
There are two of those. However, some scientists refer to the northern tip of the mainland as a temperate climate zone. In these areas, despite severe weather conditions, there is no polar day and polar night. The geographical position of the mainland is the reason that does not allow the ice cover to melt.
This happens despite the fact that the surface of the planet in this area receives a fairly large amount of thermal solar energy. Peculiar and unique weather conditions can be considered one of the mysteries of the climate of Antarctica.
The nature of the mainland - the main features
This continent is located above all others above sea level. This circumstance is connected with the most powerful shell of ice covering the surface of the mainland. Its cover reaches a thickness of 4.5 thousand m. Such a grandiose ice shell affects the climate formation of the entire planet.
What is the most extreme climate in Antarctica? Particularly harsh conditions are in the inland regions. Precipitation is practically non-existent. Their total volume is no more than 50 mm per year (on the rest of the planet, precipitation falls in an annual volume in the range from 100 to 250 mm). The temperature of the deep regions often drops to -64 ⁰С in winter and -32 ⁰С in summer. The minimum temperature recorded on the globe was about 90 ⁰С. This indicator was recorded by researchers at the Vostok station.
The deep regions of the continent are characterized by strong winds with speeds reaching 80-90 m/s. The wind blowing from the inland region intensifies as it reaches the coast.
What climate in Antarctica can be called relatively gentle? The subarctic zone is characterized by some softness. Part of the northern tip of the land falls there. Precipitation in excess of 500 mm per year is formed in this belt. In summer, the air temperature here rises to zero.
The subarctic climate zone has a less powerful ice cover. In some places the landscape consists of rocky islets covered with lichens and moss. The influence of the inner Arctic regions on the coast of the mainland leads to their unsuitability for human existence.
On the radiation balance of the continent
For a long time, scientists have been doing research, studying the harsh climate of the Arctic and Antarctica. The project was related to the compilation of the land radiation balance. They measured the radiation received from the sun, as well as reflected from the ice and snow surface. As a result, it was found that about 80% of the solar energy is reflected from the surface of the snow cover, and the remaining 20% is absorbed by the earth with transformation into heat, most of which is dissipated in the form of radiation into space.
Scientists have calculated that the southern continent uses no more than 5% of the energy received from the Sun for its own needs. Such an energy balance is inherent in Antarctica only in the summer (November - February). In winter, the duration of which is from March to October inclusive, the surface of the Earth there does not receive solar heat at all. At the same time, thermal energy is lost with the same intensity as in summer. Winds blowing from the tops of the mainland mountains contribute to the decrease in temperature.
Polar day and night in the Southern Hemisphere
As in the Northern Hemisphere, there are periods of polar day and night in Antarctica. According to astronomical calculations, December 22 is considered the day of the summer solstice, and June 22 - the winter. The sun (according to astronomers) these days "must" be only half hidden (and, accordingly, shown) relative to the horizon. The phenomenon of astronomical refraction, which consists in the refraction of light rays in the atmosphere, leads to an increase in the duration of observation of a celestial body.
We can only talk about the change of night and day in the southern latitudes, which is familiar to all of us, only in the autumn and spring periods. In winter, the mainland plunges into the conditions of the polar night, in the summer there is a polar day around the clock.
Summer in Antarctica
On the coast of the mainland, the climate of Antarctica is characterized by warm periods lasting a week or more. The underlying surface is not supercooled much. Instead of radiating heat into the atmosphere, it absorbs it from there at that time. The radiation balance takes on a positive value with an increase in the temperature of the medium.
Air circulation carries to the shores of the mainland, in addition to heat, also cold air masses - from the depths of the land. Descending from the ice sheets, they partially warm up. The winds circulate in a very peculiar way. Most often during the year it turns out to observe their movement from the same sector. Depending on its location, extremely fast and abrupt weather changes are possible.
Scientists of two scientific stations - Amundsen-Scott and Vostok - are monitoring the climate of Antarctica in the center of the continent. The average winter temperature of the inner regions recorded by them is about minus 60-70 ⁰С, summer - minus 25-45 ⁰С. The highest temperature was recorded in 1957 at the Vostok station and amounted to -13.6 ⁰С. This temperature jump was explained by a sharp invasion of the territory of the mainland by an oceanic cyclone.
The Amundsen-Scott station is located at the South Pole. Due to the relative proximity of the coast, the climate here is relatively mild. In summer, there is a large amplitude of temperature fluctuations compared to winter.
Is it warm on the mainland?
In the coastal regions of Antarctica (especially on its peninsula), the temperature in summer can rise to +10 ⁰С. The warmest month there is January. The temperature on the coastal slopes at this time is +12 ⁰С.
In July, the coastline area has temperatures from -8 ⁰С (peninsular zone) to -35 ⁰С (ice shelf). The average annual wind speed is about 12 m/s, but under certain conditions, air masses are able to move at a speed of 90 m/s. The humidity of the air masses descending from the mountains is 60-80%. In some areas, it can significantly decrease.
In rare cases, light cloudiness with precipitation in the form of snow can be observed in the peninsular zone. On the slopes in the lower region, the amount of precipitation is greater - this figure reaches 600-700 mm, at the foot - 400-500 mm.
The combination of a large amount of precipitation with powerful air currents leads to the appearance of frequent snow blizzards in this region of the mainland.
Antarctic currents
The oceans have a warming effect on the mainland, due to which the temperature on the coast rarely drops below -40 ⁰С. The average annual value of the indicator is -10-12 ⁰С in coastal areas and up to -5 ⁰С in the north of the Arctic Peninsula.
In areas of a few oases, the surface can warm up to a temperature of +2 ⁰С, and on some rare days - to even higher numbers. At Mirny station, cases of heating of air masses to a temperature of +8 ⁰С were sometimes recorded. The total duration of such periods is quite short and amounts to no more than 1000 hours during the Arctic summer.
Oases in Antarctica
The oases existing on the mainland (the largest of them, the Dry Valleys) occupy a relatively small area. In summer, water in its liquid phase can be observed in them. In some places, lakes with fresh and salt water have been identified. The area of each such oasis (and they can be coastal, mountainous and coastal) ranges from tens to hundreds of square kilometers.
Research stations are being built on their territory. The total area of all the oases of the mainland, according to approximate estimates, is about 10,000 square meters. km. The increased temperature values of these areas are explained by the ability of open ground to enhanced absorption of solar radiation. Occasionally, the rocks warm up to a temperature of +20 ⁰С. The record was the heating of the surface to a temperature of +30 ⁰С recorded at Mirny station.
What does Antarctica look like in summer?
The heated ground causes the snow to melt quickly. In conditions of dry air, the resulting moisture evaporates rapidly. As a result, both the soil and the air of the oases remain dry. In terms of their climate, these territories resemble a cold, dry desert.
The layer of air closest to the ground is heated from the rocks with the formation of ascending air currents. As a result, cumulus clouds can be observed. The effect persists at altitudes up to 1 kilometer.
Climate of Antarctica and fauna
Surrounding the mainland, the Southern Ocean is one of the most amazing ecosystems on Earth. It is home to a huge number of the most incredible creatures. Most of them are migratory, since the climate of Antarctica does not favor permanent residence or wintering. But some species (called endemic) can only be found on this mainland. Their peculiarity is in the ability to adapt to the harsh natural environment.
Representatives of the local fauna are not at all afraid of people. Researchers have the opportunity to get close to wild animals in order to better study the Antarctic fauna. At the same time, one should take into account the ban on touching wild animals prescribed in the Antarctic treaties.
Let's briefly talk about the most interesting representatives of the continent.
mammals
The blue whale can be called the largest animal that lives on our planet. Its weight is over 100 tons. This is a truly impressive natural creation. Despite their size, whales are truly elusive. They are characterized by a highly developed intellect, freedom of movement and a complex social life.
They belong, like dolphins, to the order of mammals (the name is cetaceans), that is, they are close relatives of people, elephants, dogs and cats. Those who spend at least part of the time of the year near the coast of the continent are called whales of Antarctica. In addition to the blue whale, we can talk about the southern smooth whale, sei whale, fin whale, humpback whale, sperm whale, killer whale, southern minke whale, Kerguelen fur seal from the eared seal family.
The last mammal in appearance and manner is somewhat similar to a large dog. Such seals belong to pinnipeds and can pull their hind flippers under the body, lifting their own weight with their front ones, and therefore their flexibility on land is much higher than that of their relatives. They are found mainly on the subarctic islands.
Another Antarctic mammal is the leopard seal. This name he received because of the spotty color of the body. This is one of the largest predators of the continent. Sea leopards feed on almost any animal - squid, fish, birds, penguins, and seal cubs. They are immersed in water for no more than a quarter of an hour and mostly live near open water. They swim at speeds up to 40 km/h.
Who else can be found on the mainland
Crab-eating seals can be attributed to the category of the largest Antarctic mammals. Sometimes they lie in small groups, giving the impression of a flock, although in general they are solitary animals. Despite the name, they do not eat crabs. 95% of their diet is Antarctic krill. The rest is fish and squid. The teeth of crabeaters, shaped like a sieve, are adapted for catching krill in the water.
Weddell seals can be found in Antarctica. Unlike previous representatives of the fauna, their diet is mainly fish and squid. They are excellent divers, able to dive to depths of up to 600 m and spend more than an hour underwater. It is very difficult to estimate the size of their population due to their habitat on drifting ice and close to the Arctic Circle.
You can talk about the southern elephant seal as the largest of the seals. Its diet is mainly squid and crayfish. It also moves great underwater with deep diving. It is found throughout the continent, even deep in the south.
Birds of Antarctica
A typical representative is the Antarctic tern from the tern family - a bird of small size (31-38 cm) with a wingspan of 66-77 cm. It has a black or dark red beak and light plumage with a black cap on its head. Terns feed on krill and fish, noticing prey from the air and diving after it into the water.
The only representative of the cormorant family that can be found in Antarctica is the Antarctic blue-eyed cormorant. A characteristic feature of the appearance is a yellow-orange growth near the base of the beak and a bright eye color. Its body length is 68-76 cm.
The cormorant feeds mainly on fish. Sometimes a whole flock of birds forms a "trap" for food, diving into the water and helping each other to get it. They can dive to a depth of over 100 meters. During swimming, their wings are tightly pressed to the body, and webbed feet are actively working.
Another representative of the bird world of the mainland is the white plover, leading a terrestrial lifestyle. When walking, it is characterized by nodding its head like doves. It does not have webbed feet for swimming. The food of the plover lives on the ground. Characteristic behavior is omnivorousness and a tendency to steal food (fish and krill) from penguins. Sometimes it can feast on eggs and chicks.
Other representatives of the bird world
Among other representatives of the flying fauna of the mainland, one can mention the Cape dove from the petrel family, snow petrel, wandering albatross, southern polar skua, southern giant petrel.
Flightless birds should also be mentioned - the emperor penguin (the largest in the world, its average weight is about 30 kg), as well as the king penguin (the second largest) 70-100 cm tall, with bright plumage, eating fish and squid. Another type of penguin is the subantarctic (also known as gentoo). Its sign is a wide white stripe on the head and beak.
Other representatives of the fauna
Antarctic krill is a small crustacean that lives in large groups. Its density per cubic meter is sometimes 10,000-30,000 individual individuals. Its food is phytoplankton. Krill can grow up to 6 cm in length and weigh about 2 grams. Life span is about 6 years. It is the basis of the Antarctic ecosystem and the most common representative of biomass.
The only non-flying insect found in Antarctica is known by the Latin name Belgica antarctica. It is 2-6 mm long, black in color. The insect can withstand changes in the Antarctic climate and can exist without oxygen for 2-4 weeks, but at temperatures below -15 ⁰С it dies.
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 the minimum amounts of solar radiation on the globe. 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 cooling itself 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 the northern part of the 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).
The distribution of atmospheric precipitation over the territory of the continent, as well as in the case of temperature, is 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.
It warms Antarctica, if such a concept can be applied to the southern mainland, mainly 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 in a 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 westerly winds are of the greatest importance. The distribution of pressure in the upper layers of the atmosphere causes an influx of warm, moist air from the ocean to the mainland, which, in turn, causes precipitation over the Antarctic, 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 at 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, temperatures up to 3-4 °C above zero are possible due to 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 natural conditions of the dry cold desert are characteristic of the Antarctic oases. 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 other natural phenomena, strong western 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.
There are practically no open water flows in the Antarctic, they are replaced by rare under-ice flows, 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. During 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.
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 amount 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, the 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 the temperate zone. Within its limits there is no polar day and night, but, despite this, the conditions of the peninsula are very harsh.
On its coast, the average annual temperature is -10 degrees. At its northern tip, the air temperature rises to -5 degrees.
In the northwestern part of the peninsula, in coastal oases, the average January temperature is 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.
The most severe conditions have formed in the inland regions of Antarctica. The winter temperature here drops to -64 degrees, and the summer temperature rises to -32 degrees.
In the depths of the continent, strong winds are formed, 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, the coastline is well indented and there are bays that protrude 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 Vostok inland 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, very little precipitation falls during the year, which is a common feature of the 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.
A climatic zone is a certain part of the earth's surface with a certain climate, atmospheric circulation and the intensity of heating by the Sun.
There are 7 main types of climatic zones on Earth. Broadly speaking, they are divided into permanent and transitional. Permanent are those climatic zones in which one air mass constantly acts. And in transitional - different and changing masses. Constants include: equatorial, tropical, temperate and arctic, and transitional - subequatorial, subtropical and subarctic.
Natural zones of the Arctic and Antarctic belts
Arctic climate zone
The Siberian coast of Russia, located on the coast of the Arctic Ocean, and the islands adjacent to it belong to the Arctic zone. The exceptions are the territories of Novaya Zemlya Island, Vaigach Island, Kolguev Island and other islands located on the territory of the Barents Sea.
The Siberian coast is in the arctic climate all year round, solar radiation reaches the Siberian lands only in summer and in small quantities. And in winter, when Siberia goes into the power of the polar night, solar radiation does not reach the earth at all. Only water heats some air layers. That is why the average January temperature on the mainland is higher than on the coast.
The Atlantic influences the western territories of Siberia, bringing warm air there.
During the polar day, solar insolation increases. In summer, most of the solar energy is used to melt snow and ice. And yet the temperature rises - in July it is about 0 degrees, and on the coast it is +5 degrees. The southern part of the Siberian territories warms up to +10 degrees.
About 200-300 mm of snow falls here annually.
Antarctic climate zone
The Antarctic natural belt is located in the southern hemisphere of the Earth. It covers the territories of Antarctica, nearby islands and part of the Pacific, Indian, Atlantic oceans.
A cold harsh climate prevails here. Winter air temperature ranges from -60 to -70 degrees, and in summer - from -30 to -50. The maximum mark on the thermometer is -20 degrees.
The radiation level is quite high, about 30 kcal / cm² per month, but only a small part is used to heat the Earth's surface - 10%. Everything else is reflected into space. That is why these territories have a low radiation balance.
The amount of precipitation in the form of snow varies from region to region. The closer to the center of the mainland, the less precipitation. Strong winds blow on the coast, reaching up to 12 m / s. Storms and fogs are constant phenomena near the oceans, when at the same time it is sunny and clear in the center of the mainland.
Part of the ocean surface is covered with ice. The scale of these covers depends on the season, and at the peak it reaches 500-2000 km. in width. Icebergs are quite common here.
On land, arctic deserts dominate, covered with an ice sheet. Antarctic oases are found only in coastal areas. Some mountain ranges are also rid of the ice crust, they are called nunataks.
Greenland and Antarctica are subordinate to the Antarctic and Arctic belts.
The material contains information about the climatic zones in which the mainland lies. Describes the history of the development of the continent. Explains the cause of climate change.
Antarctica is an extremely harsh continent of the globe by climatic standards. Almost the entire continental surface lies in the range where the air temperature does not rise above zero degrees. This is due to the presence of the Antarctic Plate at the South Pole.
Antarctica has not always been like this. During the Mesozoic period, when Pangea was still at the stage of a split, the planet's climate was humid and warmer.
Rice. 1. Pangea.
After millions of years, the continental lands fell into the subpolar region of the earth's surface. This caused the glaciation of Antarctica and marked the beginning of a cooling on the entire planet. This is clearly expressed in the territories of the Southern Hemisphere.
Then there were other changes on a planetary scale.
Cold currents began to form around Antarctica under the influence of westerly winds. These processes were expressed in a general cooling on the entire planet, glaciation of the polar regions, and the emergence of vast desert regions. The climate has acquired more severe features, and at the same time it has become arid.
In what climate zones is Antarctica located?
Two climatic zones pass through Antarctica:
- Antarctic;
- subantactical.
At times, the region of the northern part of the Antarctic Peninsula is classified as a temperate zone.
Rice. 2. Climatic zones of Antarctica.
The Antarctic belt dominates almost all continental zones. The ice shell that covers this territory has a thickness of up to 4,500 thousand meters. Thanks to this, Antarctica is the highest continent on the planet. Ice on the mainland performs the function of a climate-forming component. The ice crust reflects up to 90% of the sun's rays. This factor prevents the Sun from heating the surface of the continent. The climate is extremely severe in the continental regions of Antarctica. It almost never rains there.
In certain places, total rainfall is less than 50 mm. for a calendar year. In the main zone of action of the belt, this figure is less than 250-100 mm.
The temperature amplitude in the depths of the mainland during the polar night can drop to minus 64°C. In summer, when the sun does not set, the temperature is close to minus 32°C. Here passes the pole of inaccessibility of the planet.
Rice. 3. Ice deserts.
An extremely low temperature of minus 89°C was recorded at the Vostok polar station.
The subantarctic belt runs along the northern part of the peninsula. Natural conditions in this area are somewhat milder. The amount of precipitation reaches a level of over 500 mm. in year. In summer, temperatures rise above 0°C. The ice crust in these areas is much thinner and in places turns into bare rocks, which are covered with mosses and lichens.
What have we learned?
We found out what factors influenced sharp climate changes over millions of years. We learned about critical temperature values. We studied the climatic zones of Antarctica and remembered that there are only two of them - arctic and subarctic.
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