Antarctic desert table. Arctic deserts
Most of Antarctica is a desert, devoid of both vegetation cover as well as the animal population. Vegetation in the Antarctic is found almost exclusively on the outskirts of the mainland and on the subantarctic islands, and a rich and peculiar animal world associated mainly with the Antarctic water basins and partly with the marginal strip of the mainland.
Antarctica and parts of other continents adjacent to it stand out as a special floristic kingdom. In the Mesozoic, the Antarctic continent was a major center for the formation of flora, but changing climatic conditions led to its sharp depletion and migration to the north.
The flora of Antarctica is very poor. From land plants on the mainland itself, only mosses, lichens, lower algae, fungi and bacteria are found. The most richly represented are lichens, of which there are about 300 species. They can be found on all ice-free land areas. Mosses are also quite widespread, especially on the islands, where even small peat bogs form. In total, there are about 80 species of mosses in Antarctica.
Several species of flowering plants have been found on the Antarctic Peninsula. First flowering plant became known in the South Shetland Islands in 1829, ten years after the discovery of Antarctica. southern border distribution of higher plants - 64 ° S.l. on the Antarctic Peninsula. Up to 10 species of low-growing flowering plants are common there, including pike grass (Deschampsia flexuosa) and clove colobanthus (Colobanthus quitensis) with small nondescript flowers and pale green leaves. In places they form small meadows. Vegetation on the islands is much richer. There you can find more than two dozen species of flowering plants, including Kerguelen cabbage (Pringlea antiscorbutica), a tasty and nutritious vegetable and effective remedy from scurvy. A grass from the genus of bluegrass is also widespread - tuesok (Roa flabellata), good food for sheep. All the plants of the islands are herbaceous; their flowers and leaves are almost colorless, since pollination is carried out not by insects, but by the wind.
Found in fresh "oases" a small amount of blue-green algae, which, with mosses and bacteria, form a dense mucous crust covering the bottom of reservoirs. Recently in rocks brought from Antarctica, colonies of these algae were found. Interestingly, unicellular microorganisms were not found on the surface of minerals - they fill the pores of stones at a depth of 2 mm.
Modern vegetable world characterized by endemicity, due to the long-term isolation of the development of the mainland. Mosses and lichens are found throughout Antarctica. The number of lichen species reaches three hundred, about seventy species of mosses. freshwater algae in summer time settle on the surface of water bodies, as well as on the surface of snow that melts in the summer under the rays of the sun. Accumulations of microscopic algae of red, green and yellow color create colorful spots on the surface, reminiscent of lawns from afar.
Up to ten species of low-growing flowering plants are common on the Antarctic Peninsula, including pike and clove - colobanthus with small nondescript flowers and pale green leaves.
As a result of global warming, tundra began to actively form on the Antarctic Peninsula. According to scientists, in 100 years the first trees will appear in Antarctica.
Area Antarctic deserts- 400 sq. km. ( West Coast Antarctic Peninsula). The area of the Antarctic oases is 10 thousand square meters. km. The area of ice-free areas is 40 thousand square meters. km. The biosphere in Antarctica is represented in four “arenas of life”: coastal islands and ice, coastal oases on the mainland (for example, the “Banger oasis”), arenanunataks (Mount Amundsen near Mirny, Mount Nansen on Victoria Land, etc.) and the arena of glacial shield.
From plants there are flowering, fern (on the Antarctic Peninsula), lichens, fungi, bacteria, algae (in oases). Seals and penguins live on the coast.
Plants and animals are most common in the coastal zone. Ground vegetation in ice-free areas exists mainly in the form of various types of mosses and lichens and does not form a continuous cover (Antarctic moss-lichen deserts).
Antarctic animals are completely dependent on the coastal ecosystem of the Southern Ocean: due to the scarcity of vegetation, all significant food chains of coastal ecosystems begin in the waters surrounding Antarctica. Antarctic waters are particularly rich in zooplankton, primarily krill. Krill directly or indirectly form the basis of the food chain for many species of fish, cetaceans, squid, seals, penguins and other animals; There are no completely land mammals in Antarctica; invertebrates are represented by about 70 species of arthropods (insects and arachnids) and nematodes living in soils.
Of the terrestrial animals, seals live (Weddell, seal-crabeater, sea leopards, Ross, sea elephants) and birds (several species of petrels (antarctic, snowy), two skuas, arctic tern, adélie penguins and emperor penguins).
In freshwater lakes of continental coastal oases - "dry valleys" - there are oligotrophic ecosystems inhabited by blue-green algae, roundworms, copepods (cyclops) and daphnia, while birds (petrels and skuas) fly here occasionally.
Nunataks are characterized only by bacteria, algae, lichens and heavily oppressed mosses; only skuas following people occasionally fly onto the ice sheet.
There is an assumption about the presence in the subglacial lakes of Antarctica, such as Lake Vostok, of extremely oligotrophic ecosystems, practically isolated from the outside world.
In 1994, scientists reported on rapid increase the number of plants in Antarctica, which seems to confirm the hypothesis of global warming on the planet.
The Antarctic Peninsula with adjacent islands has the most favorable conditions on the mainland. climatic conditions. It is here that two species of flowering plants found in the region grow - antarctic meadow grass and kito colobanthus.
Underwater world Antarctica |
[edit] From Wikipedia, the free encyclopedia
Antarctic desert - natural area part of the Antarctic geographical belt, which covers the island and continental land of Antarctica, the southernmost of the natural zones of the Earth.
[edit] Climate
It has low temperatures air in winter months-60 to -70 °C. The air temperature in the summer months is from -30 to -50 °C. Even in summer the temperature does not rise above -20 °C. On the coast, in the area of the Antarctic Peninsula, the air temperature reaches 10 - 12 °C in summer. It is formed not only due to low temperatures at high latitudes, but also due to the reflection of heat (albedo) in the daytime from snow and ice. Cold air rolls down from the central regions of Antarctica, forming katabatic winds that reach high speeds near the coast. Relative air humidity is 60-80%, which is due to the predominance of downward flows. Off the coast and in the Antarctic oases, the relative humidity drops to 20 and even 5%. Precipitation is presented exclusively in the form of snow: their amount reaches from 30-50 mm to 600-700 mm per year and increases up to 700-1000 mm on some ice shelves. Due to strong winds, blizzards are very frequent.
[edit] Flora and fauna
The flora and fauna are very poor and peculiar. In Antarctic oases (ice-free areas) near the coast, sparse vegetation is represented by mosses, lichens, several species of flowering plants and algae in water bodies.
There are very few land animals here: there are no flying insects, land mammals and freshwater fish. Protozoa, rotifers, free-living nematodes, and lower crustaceans live in small freshwater reservoirs on land.
In the Antarctic oases, among lichens and mosses, small mites and wingless insects live - springtails and one species of flies with rudimentary wings.
The few land-bound birds include three endemic species: the white plover feeding on penguin eggs, the pipit (Anthus antarcticus) and the yellow-billed pintail, as well as several species of penguins.
natural zones. Arctic and Antarctic deserts. the world
Endless ice desert
A person develops only in labor, in trials, in struggle, in the desire to know as much as possible in this world. Only then does he move forward, only then can he achieve something in life. To become a worthy person, you need to learn, acquire new knowledge and skills. But knowledge and skills do not come by themselves. Therefore, you need to constantly work on yourself, develop your mind and your soul, make them work, "teach and torment until dark."
Reading this poem by N. A. Zabolotsky, we begin to be convinced of the justice and correctness of the poet's instructions. We begin to understand that the soul is our "slave and queen." Indeed, we can make her work, we can keep her in in constant motion and striving forward, to drive her "through the wasteland, through the wind-blown, through the snowdrift, through the pothole." And then we will temper ourselves, temper our soul, become real people and be able to be proud of ourselves, our lives. We will rise to a higher level of development and contribute to the improvement of the whole world. But it can also be the other way around. Our soul, if we let it, can become the queen. And then laziness and indifference will take over us, they will control our lives. And we will stand still in our development, “push water in a mortar”, and maybe we will slide down. Here, in order to prevent this from happening, you need to be able to control your soul.
She has to work
And day and night, and day and night!
Short description
Democracy, according to N. Berdyaev, is an age-old beginning, good familiar to the world antiquity. However, hardly any other political concept has so many meanings and so many interpretations in contemporary literature how much democracy. Progressives have been striving for democracy for centuries social forces in the name of creating a fair state structure which would ensure the free existence of every person in society. However, in our time it is difficult to name another political phenomenon that would cause such a sharp struggle in many countries of the world as democracy, and would be the object of a wide variety of research, political experiments and speculation.
Composite satellite image of Antarctica, location of the big desert on the ground. Credit: NASA/Dave Pape.
When you hear the word desert, what comes to mind? You will most likely think of sun, sand and very little rainfall. Perhaps cacti, vultures, mesas and scorpions also come to mind, or, for example, camels and oases? But the truth is, deserts come in all shapes and sizes and can vary greatly from one part of the world to another.
As with all climates on Earth, it all comes down to some basic characteristics, which in this case include barren, dry, and hostile to life. For this reason, you may be surprised to learn that the most big desert in the world is actually in Antarctica. How do you like this fact?
Definition:
Let's break it all down. The desert is simply a very dry region that receives almost no water. To be considered a desert, an area must receive less than 250 mm of precipitation annually. But precipitation can come in the form of rain, snow, drizzle or fog - literally any form of water that is transferred from the atmosphere to the ground.
Deserts can also be described as areas where more water lost during evaporation than falls as precipitation. This certainly applies to regions that have experienced desertification, where rising temperatures (ie climate change) are causing riverbeds to dry up, rainfall patterns to change and vegetation to die out.
Deserts are often some of the hottest and most inhospitable places on earth, such as the Sahara Desert in Africa, the Gobi Desert in northern China and Mongolia, and Death Valley in California. But they can also be cold, windy landscapes where it almost never snows - like the Arctic and Antarctic.
Therefore, a hot area does not mean that it is a desert. In fact, it would be more accurate to say that deserts are characterized by a minimum amount of moisture and temperature differences. It is always said that deserts make up one third of the Earth's surface. But most of it is in the polar regions.
Antarctica:
In terms of size, the Antarctic Desert is the largest desert on Earth. with total area 13.8 million sq. km. is the coldest, windiest, and most isolated continent on the planet, and is considered a desert because its annual rainfall is less than 51mm indoors.
The solar halo is visible above the landscape and ice streams of Antarctica. Credit & Copyright: Alex Cornell.
It is covered by an ice sheet containing 90% . Only 2% of the continent is ice-free, and this land is strictly along the coasts where all land-based life (i.e. penguins, seals and different kinds birds). The other 98% of Antarctica is covered in ice, which averages 1.6 km thick.
In addition to a limited number of mammals, some cold-adapted species of mites, algae and tundra vegetation can survive there.
Despite the low amount of precipitation, Antarctica, however, experiences the strongest storms. In many ways similar to sandstorms in the desert, strong winds lift the snow and turn into snowstorms. These storms can reach speeds of up to 320 km/h and are one of the reasons why the continent is so cold.
In fact, the lowest recorded temperature was measured at the Soviet Vostok station on the Antarctic Plateau. With the help of ground measurements, it was found that on June 21, 1983, the temperature reached a historical low of -89.2°C. Analysis of satellite data showed a probable also in Antarctica on August 10, 2010. However, this value has not been confirmed.
Antarctic McMurdo Station at night. Credit: m.earthtripper.com
Other deserts:
Interestingly, the second largest desert in the world is also the extremely cold Arctic Desert. Above 75 degrees northern latitude, The Arctic desert covers an area of about 13.7 million square kilometers. Here total precipitation below 250 mm, mostly in the form of snow.
Average temperature in Arctic wilderness-20°C, reaching a low of -50°C in winter. But perhaps the most interesting aspect of the Arctic wilderness is the sunlight. AT summer months does not shrink within 60 days. Then follows winter period prolonged darkness.
The third largest desert in the world is the more famous Sahara with a total area of 9.4 million square kilometers. Average annual quantity precipitation ranges from very low (on the northern and southern outskirts of the desert) to complete absence in the central and eastern parts. Most of the Sahara receives less than 20 mm of precipitation annually.
However, in the northern part of the desert systems with low pressure from mediterranean sea lead to annual amount rainfall from 100 to 250 mm. South part The desert, stretching from the coast of Mauritania to Sudan and Eritrea, receives the same amount of rainfall as in the north. central part The desert is extremely arid and receives less than 1 mm of precipitation per year.
What is the hottest place on Earth?
Temperatures in the Sahara are quite high and can rise above 50°C. Interestingly, this is not the most hot desert on the planet. The most heat, registered on Earth, was 70.7 ° C in the Iranian desert of Deshte-Lut. These measurements were part of a global temperature survey conducted by scientists at NASA's Earth Observatory in the summers of 2003 and 2009.
In short, deserts are not only sand dunes and places where you can meet Bedouins and Berbers, or a place you have to drive to get to Napa Valley. They are distributed on all continents of the world and can take the form sandy deserts or icy deserts. After all, their defining characteristic is a pronounced lack of moisture.
In this regard, the polar regions are the most big deserts in a world with Antarctica vying with the Arctic for first place. And judging by this definition - i.e. cold, dry with little to no precipitation - you are sure to find some especially large desert somewhere else in, on, for example.
The title of the article you read "What is the largest desert on Earth?".
Where is the driest desert on earth? Do you think in Africa? Wrong. Asia or Australia? Also no. The driest part of our planet, where no precipitation has fallen for millions of years, is the Dry Valleys in Antarctica. There is practically no ice there. Figuratively speaking, this is a piece of Mars on Earth.
Where are the most salt lakes? No, not in Asia. But also in Antarctica. The salinity of the frozen lakes located in the Dry Valleys is much higher than the salinity of the Dead Sea.
The third record set by the Dry Valleys is in wind speed. The most blown here strong winds on the ground. Gust speed reaches 320 km / h.
This section of Antarctica is one of the most amazing places on the globe. But tourists in this harsh place you will not meet, scientists work there and rovers plow the soil. Therefore, few people know about the two phenomena of Antarctica - the driest desert and the saltiest lake: a place, to put it mildly, not a tourist one.
This is where NASA's Mars rovers are tested. The cold and dry climate of the valleys is very similar to the Martian. Unlike other deserts on the planet, the Dry Valleys are practically lifeless. There is no moisture and nutrients even for desert thorns, and low temperatures do not contribute to the development of life. However, scientists have discovered organisms that can exist even in such extreme conditions. These are surprisingly tenacious microorganisms found under the ice of super-salty lakes. Scientists believe that the same bacteria can live on Mars.
Dry valleys occupy a vast area of 8,000 square kilometers. On the map, this area is divided into three valleys: Victoria, Taylor and Wright.
Why is there no ice in the Dry Valleys if the temperatures there are as low as the rest of Antarctica? It's all about the lack of moisture, because there hasn't been any rain or snow for two million years! For comparison, in the second driest desert on the planet (this is Atacama in Chile), precipitation has not fallen for 400 years.
Moisture in the Dry Valleys was preserved only on the upper part of the rocks, in the Onyx River and in super-salty ice lakes. Their exceptional salinity is also the result of a lack of income fresh water to these territories.
Onyx is the most long river Antarctica, but it does not enliven these lifeless spaces. Moisture in the soil of this desert simply does not linger: it evaporates under the influence of the strongest katabani winds blowing down from the slopes.
There is a widespread misconception on the Internet that the most dry place in the world is located in Chile. In fact, the Atacama Desert is in second place behind the Dry Valleys in Antarctica. If you go deeper into Antarctica from the Ross Sea, you will reach three so-called "dry valleys" (Victoria, Wright and Taylor). Katabatic winds blow here (the most strong wind planets, reaching a speed of 320 km / h), which cause increased evaporation of moisture. Thus, the valleys have been free of ice and snow for about 8 million years. However, in some areas, approximately For 2 million years there was no precipitation at all.
Let's find out more about them...
Photo 2.
However, water in the valleys is still present - in the form of the most saline lakes on Earth. As the temperature here sometimes rises to zero, they thaw in places, giving the place a surreal look of a tropical resort. In the largest of these lakes, polar explorers even go diving. They say that at the bottom lies the mummified corpse of a seal, which inexplicably hobbled here from the coast.
Photo 3.
In the middle covered with solid snow and ice shell Antarctica gaping dark speck - it's McMurdo Dry Valleys. Today they are the driest place on our planet. For millions of years there has been neither snow nor rain!
Dry Valleys - Victoria, Wright and Taylor - cover an area of 4800 square meters(this is 0.03% of the area of the continent). The temperature there often drops to -50°C, and there is polar night for four months of the year.
The dead seal is perhaps the only representative of the local fauna. The climate here is so harsh that even bacteria are present in very limited quantities, not to mention more multicellular organisms. By the way, this was very much liked by American astrophysicists, who adapted dry valleys for testing rovers. They assure that not only the absence extra life, but also local climate very similar to Martian.
Photo 4.
This unearthly corner is dry thanks to the Transantarctic Mountains, which cover the Valleys from wedges penetrating from the south. continental ice. Dry Antarctic winds sweep snow drifts from the mountains that have had time to pack. And the heated descending air flow"absorbs" the cold, causing the evaporation of moisture. That is why there has been no snow or rain in the Dry Valleys for so long.
It may seem that there is nothing alive in the Dry Valleys. However, it is not. There are reservoirs here, which, although they are covered with ice, algae grow in them and bacteria develop. In addition, in more wet places The valleys have been found to have amazing rock-dwelling bacteria, as well as anaerobic bacteria whose metabolism is based on the processing of sulfur and iron.
It's interesting that natural conditions Mars are close to those characteristic of the Dry Valleys, so NASA conducted a test in the Valleys spacecraft"Viking", designed to explore the "red planet".
Photo 5.
Now about the most tempting. Why don't you ever get here? Firstly, Antarctic tourism in general is a very conditional thing. That is, for fabulous money, of course, you can buy an excursion to South Pole(you will be taken there by military aircraft) or a sightseeing cruise to the Antarctic islands, densely populated by penguins and seals. Adding a few thousand more on top, you can also charter a yacht and moor somewhere on the Ross Sea. However, to walk to the dry valleys (about 50 kilometers through snowdrifts), you know, it will not work. Even if you suddenly have a private jet or helicopter lying around, it is unlikely that it will fly back and forth without refueling from Chile or New Zealand. And if it does fly, it certainly won't land.
Photo 6.
In general, it remains only to envy the polar scientists. By the way, it is they who own the yellow resort tents in the photographs.
Photo 7.
By the way, if you don’t end up in the dry valleys of Antarctica, be sure to keep in mind another curious place nearby. Approximately a thousand kilometers from the Antarctic deserts is the so-called "pole of inaccessibility" - the most distant point of the continent from the coast. In addition to being the most inaccessible point on the planet, there is another attraction here - an abandoned polar station topped with a bust of Lenin. It was founded by Soviet polar explorers in 1958 and lasted exactly two weeks, after which it was closed (obviously due to complete uselessness). However, the fact of our presence at the most inaccessible point on the planet was recorded. What, by the way, were convinced by three Englishmen (Rory Sweet, Rupert Lognsdon, Henry Cookson), who in 2007 for the first time reached the pole of inaccessibility on foot, using traction kites, and took pictures with Lenin.
Photo 8.
Mummified corpses of seals lie here and there in the valleys. In the cold, dry air, decomposition is slow, and some of these animals may have entered and died hundreds or even thousands of years ago. What the hell they needed here is completely incomprehensible; the only assumption is that the seals crawled into the valleys due to some kind of damage to the central nervous system and loss of orientation, and here they remained, exhausted.
And here is another opinion on the Internet: As for seals, it turns out that this is not such a mystery. Here Dima skyruk, who worked as an ichthyologist in Chukotka, writes in the comments: “As for seals, in the same Chukotka there was a case when the sea froze over, and walruses walked overland - 60 kilometers, to rivers or warm lakes, or in general - to find at least any thaw. Seals, of course, are not walruses, but personally I was not surprised to see this photo. You never know what could force a seal to walk 30 km overland. It's not that far. The animal was most likely already old and toothless (Antarctic seals wear down their teeth when they gnaw through and maintain ventilation holes in the ice).")
Photo 9.
The sand, as far as can be judged from the photographs, is frozen like concrete and forms a characteristic permafrost mesh pattern - between the particles of the soil there is a certain amount of frozen moisture. Where there is more of it, photosynthetic unicellular endolithic algae live - right inside the stones, in microcracks under the surface of the cobblestones, at a depth of from microns to several millimeters - depending on the transparency of the mineral. They live slowly, and they do not need much - a little sunlight, carbon dioxide from the atmosphere, condensing water vapor and microelements: now some organics are ready. And where there is organic matter, there are fungi and bacteria. At the top of this food pyramid are three types of microscopic, no more than 1 mm, nematode worms. In principle, there is still moss, but it has not worked for a long time - it is sublimated and preserved by cold. Waiting, frozen into the ground, the next global warming. That's all.
Photo 10.
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Although no, not all. There are frozen lakes in every valley, with lenses of brine beneath the ice sheet. The largest of them - Wanda, more than 60 m deep - is bound by a four-meter-thick ice shell. The ice acts as a greenhouse glass, and the temperature at the bottom of the lake on a polar day, according to calculations, can reach +25°C. In these worlds closed for thousands of years, perhaps, some microorganisms also live, developing according to their own laws, just waiting to be discovered.
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