Features of the nature of Antarctica. Geographic location of Antarctica
Glacial relief (8 min.)
You read in the textbook that about 1/3 of the surface of the mainland lies below sea level. Why do you think?
Scientists have found that the continent sank 0.5 km below sea level.
Remember the name of the science of ice in all forms and formations?
When drilling ice in Antarctica, glaciologists found that the glaciation of the mainland began about 360 million years ago.
The Antarctic ice sheet is the largest on the planet. It contains 90% of all land ice. (10 times more than in Greenland. Enough to cover the entire surface of the Earth with a 50-meter layer of ice)
geographic challenge.
Scientists have calculated that if the ice sheet of Antarctica completely melts, the level of the World Ocean will rise by almost 60m. What are the consequences of this?
The thickness of the ice sheet is not the same. Read the text of the textbook on p.195. Answer the questions.
What is the average thickness of the ice sheet?
Name the maximum thickness of the ice sheet.
Look at the picture on the slide. In what part of Antarctica is the thickness of the ice sheet at its maximum?
Why do you think?
The figure shows that the ice sheet has the shape of a dome, raised in the central part. Due to its own gravity, the ice is constantly moving from the interior to the coast. Thus, outlet glaciers are formed.
Annually, 20% of the ice discharged by Antarctica enters the sea through them. Huge boulders continental ice carried away by currents from the coast in the form of icebergs. They reach huge sizes (170 km x 40 km) and can swim for 10-12 years. In one of ice mountains We saw frozen shelves with crockery. These were the remains of one of the American expeditions.
Flowing from the hinterland to the coast, ice is constantly reclaiming space from the oceans. Expanding at such a rate, in 5000 years Antarctica would have doubled its area, and in 20 thousand years it would have united with Africa, Australia and South America. But the ocean, in turn, tears off the ice from the mainland and carries them into warm waters.
Antarctica is the main area where icebergs form on the planet.
Another type of glaciers characteristic of Antarctica is ice shelves. They are formed almost along the entire coast of the mainland.
Ice shelf - the marginal part of the sheet glacier facing the sea; one part rests on the shelf, the other represents an ice floating field.
On the physical map Find the largest ice shelves in Antarctica.
The largest ice shelf in Antarctica is the Ross Glacier. It is located in western Antarctica. The length of its northern edge reaches 950 km, and the height of the sheer ice ledge, called the Ross barrier, in some places exceeds 70 m, which is approximately the height of a twenty-story building. Area 538 thousand square meters. km, the thickness of the ice reaches 700 m. It was discovered in 1841 by the expedition of J.K. Ross.
On the periphery of the ice cover there are ice-free areas, which are called the Antarctic oases.
Read the text of the textbook on pages 198-199.
What are Antarctic oases?
How are they formed?
The largest oasis in Antarctica is the Bunger Oasis in Dronning Maud Land. Dimensions: 50 km by 20 km. The area is about 750 sq. km.
The Schirmacher oasis, where the Antarctic station Novolazarevskaya is located, was called a resort by polar explorers, because the soil around it can heat up to +30 0 C.
Make the main conclusions about the ice sheet of Antarctica.
Working with cards
Ice cover.
- How much ice is in the Antarctic ice sheet?
- In what direction is the continental ice moving in Antarctica?
- What is the average thickness of the ice sheet?
- Why did the polar explorers call the Schirmacher oasis a resort?
- Name the world's largest and longest ice shelf.
- Choose associations for the word "Iceberg".
Antarctica is a unique continent globe. The nature of Antarctica is very similar to the nature of the Arctic.
General characteristics of the nature of Antarctica
Antarctica is considered to be the coldest place on the planet. The land of the continent is represented by huge ice blocks, the thickness of which reaches 5 km. The lowest temperature on this continent is 80 °C.
The warmest place in Antarctica is located on the Antarctic Peninsula, the average summer temperature here rises to 0 ° C. In these areas of the mainland there is primitive soil, on which plants sometimes sprout in summer.
The relief of the continent is completely hidden by ice. On the eastern part of the mainland are the transantarctic mountains. Mount Vinson is the highest point in Antarctica, its height reaches 5145m. The territory of Antarctica is washed by the waters of the Atlantic and Pacific oceans.
Antarctic oases
Antarctic oases are a few areas of Antarctica, which are dominated by relatively favorable climatic conditions. On the territory of the Antarctic oases, ice does not cover earth's surface which allows the germination of mosses and lichens.
Antarctic oases serve as a refuge for some species of birds and animals. It is here that penguins and seagulls build their nests in order to hatch their future offspring.
Fauna of Antarctica
The most numerous representatives of the animal world in Antarctica are penguins. Emperor penguins are especially common here. They differ from other representatives of their species in high growth, which reaches 120 cm. Penguins settle large groups in coastal areas.
Penguins get food for themselves in the waters of the ocean. Whales also live in the waters of Antarctica, which make annual migrations with the onset of winter in Antarctica.
Also in Antarctica you can meet gulls and petrels. The waters of Antarctica are home to many species of fish that are food for penguins and birds of prey.
Flora of Antarctica
The plant world in Antarctica is unusually scarce. There is very little water in the tissues of plants that grow on the territory of this continent - because otherwise, the plant cells become iced up, which leads to their death.
The flora of Antarctica includes only five varieties of plants: mosses, flowering plants, liver mosses, algae and lichens. All plants are short.
The territory of Antarctica is in the Antarctic and Subantarctic. The boundary between them runs in the ocean, and only the northwestern tip of the Antarctic Peninsula belongs to the subantarctic belt. The Antarctic polar climate is determined by the Antarctic over Antarctica and Antarctic air masses. The snow limit is everywhere along the coast near sea level.
In winter, for several months, there is a polar night here. During the long polar day, the mainland receives a lot of solar radiation, but up to 90% of it is reflected by the ice surface. The coasts of the mainland are influenced by stable high and low pressure areas of the Antarctic, which determine unstable conditions. The territory of the ice sheet of Antarctica by complex natural features and processes are divided into four concentric zones: central, katabatic winds, Antarctic coast and oceanic.
Low temperatures prevail throughout the year in Antarctica. Average winter July temperatures range from -60°C inland to -32°C on the coast. In Antarctica, the lowest temperature on Earth was recorded -91.2 ° C. The previous record recorded at Vostok station was two degrees higher. Summer January temperatures are much higher, but they are also negative and range from -32 °С to -16 °С. On the coast of the mainland, the air temperature rarely drops below -40 ° C in winter, and rises to 0 ° C in summer.
Due to the strong constant cooling of the air, a huge high area is formed over the mainland, which, together with the World Ocean, has great importance on the general circulation of the Earth's atmosphere. Cold air masses flow down from the high central regions and ice domes to the outskirts of the mainland, forming strong katabatic winds (up to 30-50 m/s and more). The maximum wind speed in Antarctica was recorded by the Belarusian polar explorer A. Gaidashov - 88 m/s. The winds are very powerful, tearing and moving loose loads over long distances. The dry snow they carry can cut through thick ropes. At low temperatures, due to hypothermia, the metal loses its properties and breaks into pieces, like glass.
At high pressure and low temperatures in the central part of the mainland there is little precipitation (50-100 mm). Significantly more precipitation falls on the Antarctic islands located in the subantarctic belt. The climatic conditions here are less severe: winter temperatures are slightly below 0 °C, summer temperatures rarely exceed +10 °C. But even here they blow (up to 75 m / s), which are caused by strong sea storms. The zone of the Antarctic coast and the oceanic zone is characterized by the most intensive accumulation of snow and the loss of the ice sheet.
Flora and fauna of Antarctica
Antarctica is almost universally cold Antarctic - a surface with harsh conditions for the development of life (lack of soil, low temperatures, strong). Life on the mainland exists only in the coastal zone, on the subantarctic islands and in ocean waters. The vegetation of the mainland is represented by mosses, lichens, algae and microscopic fungi.
In the zone of the Antarctic deserts, three subzones are distinguished: the northern one - the northwestern part of the Antarctic coast and adjacent islands, the middle one - coastal oases, islands and mountain ranges, and the southern one - land within the continent. Lichens are found in Antarctic oases - in areas free of ice. They in Antarctica differ in color - from black to bright orange. So lichens adapt to local conditions, strive to get as much solar heat as possible. Algae appear in the lakes formed in summer. And only in the north of the Antarctic Peninsula and on the islands are low-growing higher plants with small flowers found.
Despite the harsh natural conditions, altitudinal zonality manifests itself in Antarctica: the lower coastal belt with the maximum diversity of nature (oases, ice shelves), the middle belt (icy deserts with snow) and the belt of eternal frost without signs of life.
The fauna of Antarctica is poor. There are crustaceans, wingless insects, some species of birds. Penguins are the most interesting representatives of birds. Penguins move slowly on land but are good swimmers. In total, four species of penguins out of 18 found on Earth live in Antarctica. About 10 species of penguins are known in coastal waters and on the islands.
The most common species is the Adélie penguin. Its height is up to 30 cm, weight - several kilograms. The largest is the emperor penguin. Its height reaches more than a meter, and its weight is up to 50 kg. These penguins breed their offspring in the harsh winter. Females lay eggs, and males, holding them on their paws and pressing them to the fluff of a warm belly, "stand" the chicks.
The richest vegetable and animal world coastal waters. The largest mammals are found here - cetaceans, including the blue whale, or vomit (up to 33 m in length, weighing up to 150 tons), fin whales, sperm whales, killer whales (predators from the dolphin family), as well as pinnipeds - seals, elephant seals, marine lions. Several species of seals live in Antarctic waters, different from their northern relatives. This indicates their adaptability to harsh waters. Shearwaters, gray gulls, or skuas nest along the coasts of Antarctica. Birds feed on fish or small marine animals.
Gray gulls are the most predatory birds of Antarctica, they feed on the eggs of penguins, petrels, and also attack small chicks.
Fish abound in Antarctic waters. On the vast expanses of the sea, microscopic algae form "ocean pastures". A lot of krill - the smallest crustaceans.
Scientists believe that the annual catch of krill in the amount of 70-80 million tons (at the level of the world's fish catch) without damage to the Antarctic ecosystem will be able to provide half of the world's population with 20 g of animal protein per day. The sale of food products from 10 million tons of krill is equivalent to 3 million tons of beef in slaughter weight. Scientists have calculated that the annual production of this species in the oceanic zone of Antarctica is 1.7-1.8 billion tons, and the total biomass is up to 6 billion tons. mankind for 7 years.
The harsh climate of Antarctica is formed due to the peculiarities of the geographical location, the presence of an ice cover and is the cause of an extremely poor organic world. The mainland is almost everywhere a cold Antarctic (biological) desert. Antarctica is playing key role in the atmosphere and climate of the planet.
General characteristics of the nature of the mainland
Remark 1
Today, everyone is well aware that the coldest continent on the planet is Antarctica, where during the long polar night the surface cools down. In summer, ice and snow reflect $90$% of solar radiation, so the average daily temperature stays at $30$ degrees. The lowest temperature is typical for Vostok station. Here is the cold pole of the Southern Hemisphere with a temperature of $89.2$ degrees. It is much warmer on the coast - about $0$ degrees in summer, and winter frosts are rather moderate - $10$, - $25$ degrees. Cooling is associated with the formation of a baric maximum in the center of the continent. This is an area of high atmospheric pressure, from which constant katabatic winds blow towards the ocean. With distance from the coast in the band $600$-$800$ km they are especially strong. The average annual precipitation on the mainland is $200$ mm, and closer to the center of the mainland, their amount is reduced to a few tens of millimeters. In such climatic conditions, the Antarctic desert formed on the main part of Antarctica, devoid of flora and fauna. Oases can be regarded as centers of life on the icy continent.
The flora of Antarctica is represented by lower plants - $80$ species of mosses, $800$ species of lichens and microscopic algae. Bacteria were found in the snow near the Pole of Cold. The animal world is connected with the seas washing the mainland, where in summer dozens of bird species nest on the coastal rocks - albatrosses, skua gulls, petrels, penguins. The most characteristic of the mainland are Adélie penguins and large emperor penguins. They can make long transitions deep into the continent. Sperm whales, killer whales, seals, whales are inhabitants of coastal waters that are rich in plankton, especially small crustaceans (krill). Previously, the Antarctic waters were a prey area for cetaceans, pinnipeds, krill, and today, due to severe depletion, many species of animals are taken under protection.
Antarctica itself and parts of other continents adjacent to it stand out as a special floristic kingdom. In the Mesozoic era, there was major center flora formation. Changed climatic conditions led to its impoverishment and migration to more favorable northern regions.
Vegetable world
The natural features of Antarctica are explained by harsh climatic conditions, and the flora of the continent is extremely poor. Numerous are algae, of which there are about 700 species. The plains and coast of the mainland are covered with mosses and lichens in summer.
But there are $2$ species in this harsh land flowering plants – colobanthus kito, belonging to the clove family, and Antarctic meadow grass. Colobanthus kito is a herbaceous, low cushion-shaped plant. Its flowers are very small, pale yellow and white color. An adult plant has a height of no more than $ 5 $ centimeters and belongs to the family of cereals. Both plants grow only in well-heated rocky soil, despite being adapted to harsh conditions and withstand frost. Their growing season is short.
Blue-green algae, together with bacteria and mosses, cover the bottom of fresh water bodies, forming a dense slimy crust. Algae are among the most ancient plants of Antarctica, the fossilized remains of which were found on the surfaces of minerals. The entire surface of water bodies is covered with these plants in summer, but they can settle even on melted snow. With a large accumulation, they form bright lawns. The illusion of red snowfall is associated with these microscopic algae, when strong gusts of wind tear them off the surface, lift them into the air and mix with snow grains.
Giant algae are found in the Antarctic seas, having a length of $150$-$300$ m. They bear the common name of maktotsitas, which means "large-celled" in translation. Indeed, in comparison with other plants, algae have huge cell sizes. Colonies of these amazing plants form real underwater forests.
The second, most common representative of the flora of Antarctica after algae, are lichens. These plants, which are a symbiosis of fungi and algae, belong to the lowest class. Some representatives of this plant are more than $10$ thousand years old. Managing to grow among the rocks and catching the rare rays of the sun, plants carry out the process of photosynthesis.
The colors of lichens are surprisingly diverse - light green, orange, yellow, nondescript gray and even completely black. Lichens with black pigment are generally a rare event on the planet, but in Antarctica they are most common. This is explained by the fact that due to the dark color, the plant absorbs maximum amount sunlight and warmth. The plant clings to the rocks so tightly that it is impossible to scrape it off with your hands, which is why they are called “scale lichens”. Lichens can also be deciduous, growing like miniature bushes. In the conditions of the Antarctic climate, the growth of lichens takes a very long time, because it is inhibited by low temperatures and strong winds.
Remark 2
The poor species composition of the flora of Antarctica is characterized by endemicity due to the long-term isolation of the development of the mainland, as a result of which a few plants have adapted to eternal cold.
Animal world
The natural features of Antarctica left their mark on the fauna of the mainland, which can only live in those places where there is vegetation. The fauna of the mainland is conditionally divided into $2$ independent groups - aquatic and terrestrial, while it is important to note that there are no animals permanently living on land in Antarctica.
The terrestrial fauna is very poor, there are some worms, primitive crustaceans and wingless insects. In principle, insects do not need wings here - due to constantly blowing strong winds, they simply cannot rise into the air. On island land, scientists have found several species of beetles, spiders, one species of flightless butterfly. Of the birds living on land, the white plover, the pipit, one species of duck that nests on the island of South Georgia are known. The native inhabitants of Antarctica are the Adélie penguins, most spending time in the ocean because the water temperature is higher. They come to the surface only for nesting. Males are very sensitive to the choice of a partner. Having chosen a female, the male brings her a pebble, chosen especially for her. By accepting this gift, the female becomes a companion for life. The chicks gather in the “crèche”, where they spend $2$ of a month, and after this period they already independently get their own food. The penguin's daily ration is $2$ kg of food. Penguins are not the only animals on the mainland.
The seas surrounding Antarctica are home to the largest mammals - cetaceans. They are divided into baleen and toothed whales. Baleen whales are especially well studied because they are the main object of whaling. In this subgroup, blue whales, fin whales, humpback whales, real whales stand out. The largest of the whales, the blue whale (vomited), together with the fin whale, is of the greatest commercial importance. They have an average length of $26m, but the longest whale killed in Antarctic waters was $35m.
Large whales typically weigh up to $160 tons and yield $20 tons of pure blubber. The food for these giants are small crustaceans that live in abundance in cold waters. Toothed whales include sperm whales, bottlenose whales, killer whales, which are very dangerous predators. With the help of a sharp dorsal fin, a killer whale can cause a dangerous injury even to a whale. Killer whales hunt in packs and do it successfully and sophisticatedly, attacking fur seals, seals, sperm whales, dolphins, sea lions.
Killer whales have their own approach to each “victim”, for example, when hunting for seals, they use the ledges of the seabed as an ambush. A group dives under an ice floe when hunting for penguins in order to immediately knock several individuals into the water. Large whales are hunted mainly by males, at the same time attacking the prey and preventing it from rising to the surface of the water. By attacking the sperm whale, killer whales, on the contrary, do not allow it to go into the depths of the sea. These animals are characterized by a developed social structure. They have so-called maternal groups, which include a mother with a cub, her adult sons and several more families headed by relatives of the main killer whale. Such a social grouping can include up to $20$ of individuals that are sufficiently attached to each other. Each flock has its own dialect.
It is interesting that killer whales take care of crippled or old relatives, and their relations within the flock are more than friendly.
The most common true seals include the Weddell seal, which can reach $3$ m in length. immovable ice. On the floating ice there are other types of seals. These include the crabeater seal and the leopard seal, which has a peculiar spotted skin. Of the seals, the largest is the elephant seal, which in to a large extent already exterminated. On the Antarctic outskirts, there is an eared seal, so named because of its well-defined mane.
The bird world of Antarctica is peculiar. In summer, petrels, gulls, cormorants, albatrosses fly here, with a wingspan of up to $3.5 m.
Remark 3
In Antarctica, the thesis of evolution - "Survival of the fittest" is fully confirmed. For the inhabitants of the mainland, life is a daily struggle with low temperatures, a struggle for the most convenient place to get food. Strong and formidable to their enemies, the animals of Antarctica are caring and friendly in their pack or colony. The animal world of the continent is dangerous and harsh, but magnificent in its own way.
1. Complete the sentence.
The main feature of the geographical position of Antarctica is its position beyond the Antarctic Circle.
2. Fill in the gaps in the sentences.
Antarctica is the most southern mainland. Its area is 14 million km2. The average height of the mainland is about 2050 m above sea level. home distinguishing feature nature - a very harsh and cold climate. Antarctica is entirely covered by a thick ice sheet. The lowest temperature on Earth is recorded here. It is -890C. almost the entire territory of Antarctica is located in natural area Antarctic deserts. At the South Pole, all directions are north.
4. What is the contribution of these travelers to the exploration of Antarctica?
F.F. Bellingshausen - discovery of Antarctica.
M.P. Lazarev - the discovery of Antarctica.
R. Amundsen was the first to reach the South Pole.
R. Scott - Scott's second expedition reached the South Pole.
5. Sign on the contour map the oceans and seas washing the shores of Antarctica. Draw and sign ocean currents along its shores. What are the characteristics of currents?
Antarctica is surrounded by the most powerful westerly current in the World Ocean.
6. Apply to contour map Antarctica Cape Sifre, Mount Erebus, Vostok Station. Define them geographical coordinates and sign.
8. Why is Antarctica called the source fresh water? How can you get Antarctic fresh water? Submit your project.
Enormous resources of clean and fresh water (about 2 thousand km3) are contained in icebergs, 93% of which are provided by the continental glaciation of Antarctica. This means that the bulk of the world's fresh water reserves are, as it were, conserved in the ice sheets of Antarctica. The formation of icebergs, which break off from the edge of the glacier, set off, so to speak, to free float in the Southern Ocean, is directly related to the ice sheets and shelves of Antarctica. According to available calculations, in total, from 1400 to 2400 km3 of fresh water in the form of icebergs annually breaks off from the retractable and shelf ice shelves of Antarctica. Antarctic icebergs spread across the Southern Ocean within 44–57°S. sh., but sometimes reach 35 ° S. sh., and this is the latitude of Buenos Aires. It is these icebergs that can be transported and used as sources of fresh water.
9. Is it possible for a day to last 180 days? As one of the eyewitnesses writes, “the sun went in a circle almost at the same height, and it was impossible to guess what time it was, or to figure out which way it was south.” Explain where it could be and why?
A day can last half a year beyond the polar circles (polar day). If it was impossible to determine where the south is, then we are most likely talking about the north pole.
10. What letter on the map (Fig. 16) indicates Cape Sifre?
BUT); AT); FROM); D)
11. The first to reach the South Pole:
1) R. Scott;
2) R. Amundsen;
3) G. Sedov
2) R. Amundsen
12. Choose an erroneous statement:
1. Antarctica is part of Gondwana.
2. The main distinguishing feature of nature is the harsh climate.
4. Strong katabatic winds blow on the mainland
3. R. Amundsen discovered Antarctica.
13. Specify the excess:
1) blue whale;
2) polar bear;
3) penguin
polar bear
14. Which of the statements is correct?
a) Antarctica is the highest continent on Earth.
B) Among the animals in Antarctica there is a polar fox.
1) only A is true;
2) only B is true;
3) both are true;
4) both are wrong