Geographical location of deserts. Climatic conditions of deserts and semi-deserts

Desert is a natural area characterized by flat surface, sparseness or absence of flora and specific fauna.

There are sandy, rocky, clayey, and saline deserts. Arctic deserts are distinguished separately. Polar desert) in Antarctica and the Arctic. They can be snowy or snowless (dry). The area of ​​snow deserts accounts for more than 99% of the total area arctic deserts. The McMurdo Dry Valleys are a snowless (dry) desert. The area of ​​these valleys is 8 thousand km² (less than 0.06% of the 14.1 million km² of the total area of ​​Antarctica). Katabatic winds (cold air currents directed down slopes earth's surface, which arise due to the cooling of air on glaciers and are carried down due to greater gravity) cause the evaporation of moisture. Thanks to this, the valleys have been practically free of ice and snow for about 8 million years.

The most famous sand desert is the Sahara (the largest sand desert by area), which occupies the entire northern part of the African continent. Close to deserts are semi-deserts, which also belong to extreme landscapes.

In total, deserts occupy more than 16.5 million km² (excluding Antarctica), or about 11% of the land surface. With Antarctica more than 20%.

general characteristics

Deserts are common in the temperate zone of the Northern Hemisphere, subtropical and tropical zones of the Northern and Southern hemispheres. They are characterized by moisture conditions (annual precipitation is less than 200 mm, in extra-arid areas - less than 50 mm, and in some deserts there has been no precipitation for decades). The relief is a complex combination of highlands, small hills and island mountains with structural strata plains, ancient river valleys and closed lake depressions. The erosional type of relief formation is greatly weakened; aeolian landforms are widespread. For the most part, the territory of the deserts is drainless, sometimes they are crossed by transit rivers (Syr Darya, Amu Darya, Nile, Yellow River and others); There are many drying up lakes and rivers, often changing their shape and size (Lop Nor, Chad, Eyre), and periodically drying up watercourses are typical. Groundwater is often mineralized. The soils are poorly developed and are characterized by a predominance of water-soluble salts in the soil solution over organic substances, salt crusts are common. The vegetation cover is sparse (the distance between neighboring plants is from several tens of cm to several meters or more) and usually covers less than 50% of the soil surface; in extra-arid conditions it is practically absent.

Sandy deserts are inhabited by plants mainly by thorny bushes, and by animals - reptiles and small steppe animals. In sandy deserts above areas where groundwater occurs, there are oases - “islands” with dense vegetation and ponds. Snowy deserts are mainly located in the Arctic Circle and are inhabited by animals that are resistant to cold.

Desert classification

According to the nature of soils and soils:

• Sandy – on loose sediments of ancient alluvial plains;
• Loess - on loess deposits of piedmont plains;
• Loamy – on low-carbonate cover loams of the plains;
• Clay takyr - on piedmont plains and in ancient river deltas;
• Clayey - on low mountains composed of salt-bearing marls and clays,
• Pebble and sand-pebble – on gypsum plateaus and piedmont plains;
• Rubbly gypsum – on plateaus and young piedmont plains;
• Rocky – in low mountains and small hills;
• Solonchak - in saline depressions of the relief and along sea coasts.

According to the dynamics of precipitation:

• Coastal – develop where cold coasts approach hot coasts sea ​​currents(Namib, Atacama): almost no precipitation; life, respectively, too.
• Central Asian type (Gobi, Betpak-Dala): the rate of precipitation is approximately constant throughout the year - and therefore there is life here all year, but it barely glimmers.
• Mediterranean type (Sahara, Kara-Kum, Great Sandy Desert in Australia): there is the same amount of precipitation as in the previous type, but they all fall at once, in two to three weeks; here there is a brief and vigorous flowering of life (various ephemera), which then passes into a latent state - until next year.

How do deserts arise?

Historical experience shows that degradation natural environment As a result of forest destruction, it occurred in the following sequence: deforestation - the emergence of savannas - desertification. Several thousand years ago, the Sahara arose on the site of savannas, and even earlier, a significant part of this territory was occupied by forests.

Desertification is the final stage of soil destruction. After deforestation, the climate changes, they go deeper fresh waters, erosion begins, and then the soil flutters. In the 20th century, desertification became global problem. Every year, advancing deserts capture up to 50 thousand square kilometers of territory where people lived only recently, and where forests roared in the recent past. The threat of desertification now affects 150 countries to one degree or another. If it develops at the current pace, 600–700 million people – a seventh of the world’s population – will be at risk of displacement. Dry lands, which are threatened by deserts, now supply meat, wool, cotton, and grain. These lands have considerable potential for further development of agricultural production. Their loss will result in yet another tragedy for humanity. The advance of deserts must be stopped.

The process of desertification has also affected the territory of our country. It is observed in Kazakhstan, in the lowland regions of Central Asia, and in Kalmykia. main reason– incorrect management Agriculture: plowing of dry steppes, ill-conceived irrigation, lack of protective forest plantings. Nowadays, the annual increase in the area of ​​semi-deserts in a number of regions of our country reaches 10 percent. True scale This process has only now begun to be elucidated using satellite observations.

Peculiarities

Relief

The topography of hot deserts is very diverse. Only some of them are completely covered with sand. The surface of others consists of stones, pebbles and other rocks. Deserts are practically open to weathering. Strong winds pick up small fragments of stones from the surface and throw them onto the rocks. Erosion is most intense near the surface, where winds throw the most sand and stones onto the rocks.

In sandy deserts, winds carry sand across the surface, forming wave-like deposits called dunes. The shape of the dunes depends on the direction of the wind and the size of the sand particles. The most common form of dunes is dunes. The dunes have the shape of a crescent. They form in deserts where winds blow in one direction. The dunes move slowly, and sand pours over their tops. Their height can reach 30m. Ridge dunes are long ridges of sand formed by winds blowing from two directions. They can be up to 100 km long and up to 100 m high.

Temperatures

IN daytime the temperature in the desert can rise to 52°C, since there are no clouds in the atmosphere and nothing protects the surface from the sun's rays. It is much cooler underground, and therefore most animals hide from the heat during the day in deep holes. At night, the temperature drops very quickly due to the absence of clouds to trap the heat emitted by the surface. During the day, the fenisk fox hides from the heat in a deep hole. She hunts at night when it is cool. Blood vessels run just under the skin of the fox's large ears. Flowing through them, the roof cools, releasing heat into the air. This helps reduce the animal's body temperature.

Rain in the desert

Although there is little rainfall in hot deserts, very heavy downpours occasionally occur, after which the water is not absorbed into the soil, but quickly flows down the surface, washing away pebbles and soil particles from it into dry channels - wadis.

The seeds of some plants in deserts can lie in the soil for many months, even years. After rain they germinate very quickly, flower, produce seeds, and then die when conditions become unbearable. Many plants in deserts have extensive root systems that absorb moisture deep from the ground. The leaves of such plants are very small in order to minimize the evaporation of moisture from their surface. Cacti, the shape of which allows evaporation to be minimized, are covered with sharp spines, they do not give animals eat them. When it rains, cacti absorb water with their juicy pulp.

Flora of tropical deserts

Primitive soils tropical deserts very poor in humus, and gray soils form only in relatively humid areas. Soil cover in tropical deserts is usually absent. Vast spaces are covered with sand or scatterings of crushed stone and pebbles, on the surface of which a characteristic shiny dark crust forms, the so-called desert tan, which protects rocks from rapid weathering and destruction.

Only plants that can grow in deserts can grow in extreme conditions drought and high temperatures. There are many xerophytes, ephemerals and ephemeroids that do not form a closed vegetation cover, unusual shrubs and subshrubs of the “tumbleweed” type. In the sandy deserts of Asia, leafless shrubs (white saxaul, sand acacia) are common; in America and Africa, succulents (cacti, agaves, aloe, etc.) are common. A variety of wormwood and solyanka are characteristic of clay deserts. Hamadas, which at first glance are devoid of vegetation, also have vegetation cover - lichens.

Where groundwater comes close to the surface, oases are located. The largest of them are located in river valleys. It's developing here irrigated agriculture and horticulture, cotton, wheat, barley, sugar cane, olive, etc. are cultivated. It grows in the Arabian and North African deserts date palm- a beautiful, slender tree up to 30 m high. Its nutritious fruits, dates, are eaten raw, boiled, fried and dried. The apical buds, flower shoots of palm trees - palm cabbage, as well as the mealy core of young palm trees are eaten.

Fauna of tropical deserts

The hot and extremely dry climate of tropical deserts is extreme for living organisms. However, the animals living in these places managed to adapt to such conditions. They may not drink for long periods of time and travel great distances in search of water. During the hottest season of the year in tropical deserts, many invertebrates go into suspended animation, and reptiles and rodents hibernate. Some animals spend almost their entire lives underground, and ungulates and most bird species live underground. summer period migrate from hot regions. Many desert animals lead night look life. They crawl out of their burrows only for a short period of time between the cold of the night and the scorching heat of the day, and some animals during the daytime hide in the shade of bushes or climb onto high branches, away from the hot ground.

In tropical deserts, jerboas, voles, mole rats, hyenas, cheetahs, desert cats, and miniature foxes are common; ungulates are represented by antelopes, donkeys, mountain sheep; birds - sandgrouses, larks. In deserts there are many reptiles (geckos, lizards, snakes), arachnids and insects (darkling beetles, phalanges, scorpions).

The one-humped camel (dromedary) is often called the “ship of the desert” for its endurance and reliability. The dromedary was once found only in the arid regions of the Middle East, northern India and northern Africa, but dromedary camels were later introduced to central Australia. Brownish or sandy-gray dromedaries weigh from 300 to 690 kg and reach a height of 2 m, sometimes black and white individuals are found. The dromedary has a long curved neck, a narrow chest and a single hump consisting of fatty deposits - food reserves - approx. from geoglobus.ru. The size of the hump varies depending on the amount of food and the time of year. Dromedar feeds on dry grass and young shoots of bushes, chewing each portion of food thoroughly (40-50 times). It needs salt to maintain its water supply.

The camel's hooves are perfectly adapted for walking on sand, and its thick lips allow the animal to eat even thorny plants. Typically, dromedaries live in family groups of 20 individuals: one male, one or more females and their offspring. Camels give birth to one calf in winter, and during the first year of life it gains weight very quickly. Dromedary camels live 40-50 years.

Typical desert birds - sandgrouses - have long and sharp wings, adapted for fast flight. They feed on the seeds of grasses and shrubs, and when they fly to a watering hole, they moisten their belly feathers, which have a special structure. In the crop and wet feathers, hazel grouse carry water to the chicks. The nest of the hazel grouse is made on the ground, and the parents take turns incubating the 3 laid eggs.

Jerboas are often found in deserts: in the Sahara - sandy ones, and in Central Asia and Iran - comb-toed, thick-tailed and hairy-footed. Funny animals with long hind legs and short “arms” resemble miniature kangaroos. Their soft, thick fur is sand-colored - approx. from geoglobus.ru. Jerboas emerge from their shallow, complexly branched burrows with several exits at nightfall. On long hind legs they gallop in search of food, reaching speeds of up to 50 km/h. The animals feed mainly plant foods, but do not neglect insects and carrion.

And in Russia there are deserts

As a rule, when deserts are mentioned, the Sahara, Kalahari and Gobi come to mind, and not everyone thinks about Russia at such moments. Mostly motherland associated with the taiga and endless snowy expanses. However, this phenomenon is not at all alien to our country. The desert in Russia is much richer flora than you can imagine. Don't believe me? Read on! Oddly enough, one of the Russian deserts is located just 800 km from the capital. Archedinsky-Don sands - this is the name of the local wasteland. Most of this territory is covered with sandy massifs left over from the times Ice Age Don.

The plants of the Russian deserts make this territory truly unique in its kind - birch bushes stretch among the sandy hillocks, black alder and aspens grow. There are junipers here, special kind cinquefoil and buckthorn. There are also saxauls, common in desert areas around the world. In spring, numerous tulips bloom in particularly humid desert areas, turning the harsh nature into a veritable parade of colors and shades. They can be called the brightest accent among the desert spring. There are practically no dangerous animals here. The most common representatives of Russian desert fauna are ground squirrels and jerboas. Of the larger animals, saigas are common in this area, and the number of bird species here is truly enormous.

Where sand gives way to ice

Let us note that the desert in Russia is not only the Tsimlyansk and Archedinsky-Don sands. These areas also include the Arctic wastelands, where heat gives way to frost. For most of the year, these expanses are covered with a thick layer of ice, and here you can only find moss that is very resistant to low temperatures. Only at the height of summer do the white wastelands transform beyond recognition - mosses and lichens acquire new colors, forming green-red carpets. Thistle and some types of cereals emerge from the frozen soil.

Flowering plants of the Russian deserts are also found here - foxtail, buttercup, arctic pike, snow saxifrage and even polar poppy. Here and there you can see sky-blue forget-me-nots and fluffy white moss. During this period, the icy, harsh desert turns into a real wonderful world, where the beauty and riot of life compete with low temperatures and strong winds. Much more striking is the diversity of the fauna of the Arctic wastelands - walruses, seals and polar bears coexist here with a huge number of bird species, deer, narwhals and beluga whales.

The driest deserts in the world

Dry deserts in Antarctica

The Dry Valleys of Antarctica can be considered the driest place on the planet, since there has been no precipitation in these places for more than two million years. The Dry Valleys include the Victoria, Taylor and Wright valleys. They are located near McMurdo Sound. This desert of Antarctica is not covered with ice, its area is about eight thousand square kilometers.

Causes of dryness in Katabatic winds. They blow at a speed of at least three hundred and twenty kilometers per hour, which is maximum speed winds on the planet. It is the wind that evaporates all the moisture. For almost eight million years, the valleys remain free of snow and ice. Dry Valleys is a protected, especially valuable area, where it is very convenient to conduct various kinds research. According to natural conditions, these valleys are close to the conditions of Mars. This similarity is used by NASA for testing.

On the territory of the valleys there is Lake Vida and the Onyx River. The water of the lake is extremely salty and exceeds even the waters of the Dead Sea in the amount of salt. Animal world in the Dry Valleys is extremely poor, despite the complete absence of ice and snow cover. This is due precisely to the increased dryness, which makes it difficult for animals to survive there.

The driest places in Eurasia

There are several deserts in Eurasia. They are located in Central, Central Asia, Kazakhstan. In Kazakhstan, the most famous deserts are the Ustyurt plateau, Betpak-Dala, Kyzylkum, Moyunkum, and the Aral Karakum desert. The desert expanses of Kazakhstan are truly immense. The fauna is represented by jerboas, vipers, gray monitor lizards and goitered gazelles. IN Central Asia The Taklamakan sandy desert can be distinguished. It is recognized as the largest in the world, but its conditions are among the most severe. The Dzungaria desert, the Alashan and Gobi deserts are famous. The deserts of Central Asia have cold winters with maximum precipitation in the summer.

In Central Asia, vast territories are occupied by deserts, where it is extremely dry and extremely hot climate. They can be classified as southern deserts, which are a continuation of the North African deserts and the deserts of Asia Minor. The largest Central Asian deserts are the Karakum and Kyzylkum. The rest are much smaller.

Hottest desert in India

One of the most significant deserts in India and the most populated desert in the world is the Thar Desert. It is located in the Indian state of Rajasthan. The climate of the Thar Desert cannot be called harsh; it is a living eco-system.

The Thar Desert is inhabited by animals. Common representatives are Indian gazelle, jungle cat, nilga antelope, jackals and foxes. Due to the low population of desert spaces with people, animals have the opportunity to live in natural conditions environment. It is common to find prehistoric-looking lizards, rat snakes, vipers and sand boas there. The amazing thing is that in the last two hundred and eighty million years there has been a sea in place of the Thar Desert.

In the area of ​​the village of Akal, petrified trees have been preserved, which are the remains of ferns and forests that grew in those places about one hundred and eighty million years ago. One of the largest petrified trees with a girth of one and a half meters and a length of almost seven meters.

8 most unusual deserts on the planet

1. Desert with lagoons - Lencois Maranhenses, Brazil

It's hard to believe, but this desert, which stretches into national park in the state of Maranhão in Brazil, full of lagoons. The spectacular view creates a contrast between the white dunes and the blue lagoons formed by the rain, the water from which collects in the lowlands between the dunes, forming small ponds with clear water. The lagoons themselves, where fish, turtles and shellfish live, can only be seen after winter and before the onset of summer.

2. Colored Desert, USA

The colored desert in the state of Arizona in the USA is an expanse of hills, plateaus and isolated hills with steep slopes. It is dry land with sparse vegetation and has been severely eroded. The name "Color Desert" refers to the variety of colorful layers of sedimentary rock that are visible against this rugged landscape. The topography of the Colored Desert is often compared to the colorful layers of a cake. The variety of shades of sandstone and mudstone layers is the result of containing different minerals in sedimentary rocks and the speed at which they were deposited.

3. The smallest desert in the world is the Carcross Desert, Canada

The Carcross Desert in Yukon State is called the smallest desert in the world. The dry climate and winds created sand dunes here and contributed to the growth of rare vegetation that adapted to environment. The size of the Cacross Desert is about 2.6 square meters. km.

4. The largest gypsum desert - White Sands, USA

Rising right in the center of the Tularos Basin, sits one of the greatest natural wonders New Mexico, USA - the shimmering sands of the gypsum desert. The dunes here cover about 712 square meters. km of land, making this desert the largest gypsum desert in the world. Unlike other deserts, the sand here is actually cool to the touch due to high evaporation and moisture at the surface and the fact that the sands reflect rather than absorb the sun's rays.

5. Black Desert, Egypt

The Black Desert is an area where volcanic hills are covered big amount small black pebbles. The pebbles lie on top of the orange-brown earth, and therefore the desert is not completely black. Climbing to one of the tops of numerous hills, you can admire the indescribable landscape, consisting of many equally beautiful gloomy hills. However, it is worth remembering that the Black Desert is uninhabited and there are no amenities here.

6. The largest salt desert is the Salar de Uyuni, Bolivia

This desert, located in Bolivia, can significantly change the way you think about deserts. It is actually a dry salt lake whose topography is completely flat, and it is so large and transparent that the sky appears to be reflected, creating a landscape of different shades of blue. Another attractive aspect of this desert is the many colorful lakes that get their color from a variety of minerals.

The Salar de Uyuni is the largest wet salt flat, extending over 10,582 square kilometers. km. The salt marsh contains a large number of sodium, potassium, lithium, magnesium, and borax. According to some estimates, there are about 10 billion tons of salt here, of which about 25,000 tons are mined annually.

7. Desert covered with snow - Taklamakan, China

Taklamakan is one of the largest sand deserts in the world, being the 15th largest non-polar desert. It extends over 270,000 square meters. km of the Tarim River basin, its length is 1000 km and width 400 km. It is crossed by two branches from the northern and southern edges silk road, to which travelers usually gravitated to avoid the arid wasteland.

In 2008, China's largest desert experienced its heaviest snowfall and recorded the most low temperatures after 11 days of continuous snowfall.

8. Red Sand Desert - Simpson Desert, Australia

Located in Australia, the Simpson Desert is striking in its beauty thanks to its red sand dunes.

Another attractive aspect is that it has the longest parallel dunes on the planet. The most famous dune is the Big Red dune, whose height reaches 40 m.

Although the climate is quite harsh, it is home to the spinifex plant, which anchors shifting sand, and is home to 180 species of birds, as well as lizards and marsupials.

Sources

https://ru.wikipedia.org/wiki/Desert https://www.factroom.ru/facts/16538 https://uznayvse.ru/interesting-facts/samyie-suhie-pustyini-v-mire.html

In the Northern and Southern Hemispheres, between latitudes 15 and 30, there is a zone of tropical deserts. Some deserts are located inside continents, while others stretch along the western coasts of continents. These are very hot and dry regions of the globe with sparse flora and fauna. There are no permanent rivers here, and vast areas are occupied only by blowing sands, piles of stones and clay surfaces cracked by the heat.

Tropical deserts

Tropical or trade wind deserts, as they are also called, include the deserts of Arabia, Syria, Iraq, Afghanistan and Pakistan; the exceptionally distinctive Atacama Desert in Chile; Thar Desert in northwestern India; the vast deserts of Australia; Kalahari in South Africa; and finally, greatest desert world - Sahara North Africa.

Tropical Asian deserts

The tropical Asian deserts, together with the Sahara, form a continuous arid belt stretching 7,200 km from Atlantic coast Africa to the east, with an axis approximately coinciding with the Tropic of the North; in some areas within this belt it almost never rains. The patterns of general atmospheric circulation lead to the fact that downward movements of air masses predominate in these places, which explains the exceptional aridity of the climate. Unlike the deserts of America, the Asian deserts and the Sahara have long been inhabited by people who have adapted to these conditions, but the population density here is very low.

The most beautiful deserts in the world

Atacama, Chile

Supposedly the oldest and driest desert in the world (only 3–15 mm of precipitation per year) consists of salt lakes, sand and hardened lava. The composition of its soil is as close as possible to that of Mars. By the way, “A Space Odyssey” was filmed here. In autumn, when the rains fall, the desert is covered with flowers.

Great Sandy Desert, Australia

In the Uluru-Kata Tjuta Nature Reserve, home to the wild dog dingo, stands the 8.6 km² red rock of Uluru, sacred to the Anangu Aboriginal people. The climb takes about an hour, and it is better to do it at dawn or at night to admire the stars.

Gobi, Mongolia

The largest and coldest (up to –40 °C) desert in Asia is famous for its fossils: it was here that paleontologists found dinosaur eggs. Park Gurvansaikhan is famous for the Hongoryn-Els sand massif stretching for 180 km, which means “singing sands”.

Namib, Namibia

Tall sand dunes come close to the ocean, where the cold Benguela Current creates fog, creating obstacles for shipping. South of the Kunene River is the Skeleton Coast - a cemetery lost ships, which is increasingly covered with sand every year.

Death Valley, California

In the depression of the Mojave Desert, southeast of the Sierra Nevada, the highest air temperature in the world was recorded, +57 °C. Ghost hunters come to the abandoned towns of gold miners, and Antonioni fans come to Zabriskie Point. Five million years ago there was a lake in this place.

Deserts and semi-deserts are a natural zone characterized by an almost complete absence of vegetation and very poor fauna.

1. Deserts are primarily found in the tropics.
Tropical deserts occupy most of the territory tropical Africa and Australia, the western coast of the tropical zone of South America, as well as the territory of the Arabian Peninsula in Eurasia.
Here their formation is associated with the year-round dominance of tropical air mass, the influence of which is enhanced by the terrain and cold currents off the coast. Climate - tropical dry

Natural conditions deserts are exceptionally harsh. The amount of precipitation here does not exceed 250 mm per year, and in large areas it is less than 100 mm. The driest desert in the world is the Atacama Desert, where no rainfall has been recorded for 400 years. The most big desert world - the Sahara, located in North Africa. Its name is translated from Arabic as “desert”. The highest air temperature on the planet was recorded here: +58°C. Under the scorching rays of the sun in summer months When it reaches its zenith at noon, the sand underfoot heats up to enormous temperatures. However, as the sun sets, the temperature in the desert drops sharply, changes reaching tens of degrees during the day, and on a winter night frosts even occur here. It's always the fault of everything clear sky Due to the downward flows of dry air from the equator, because of this, almost no clouds form here. The vast open spaces of deserts do not at all prevent the movement of air along the surface of the earth, which leads to the emergence of strong winds. Dusty sandstorms come unexpectedly, bringing clouds of sand and streams of hot air. In spring and summer, a strong wind rises in the Sahara - samum, which can be literally translated as “poisonous wind”. It can last only 10-15 minutes, but the hot dusty air is very dangerous for humans, it burns the skin, the sand does not allow you to breathe freely, many travelers and caravans died in the deserts under this deadly wind. Also, at the end of winter - beginning of spring in North Africa, a seasonal wind begins to blow from the desert almost every year - khamsin, which in Arabic means “fifty”, since on average it blows for fifty days.

2. Deserts temperate latitudes, unlike tropical deserts, are also characterized by strong temperature changes throughout the year. Hot summer gives way to cold, harsh winter. Air temperature fluctuations over the year can be about 100°C. Winter frosts in the deserts of the temperate zone of Eurasia they drop to -50°C, the climate is sharply continental.

3. Subtropical inside continental climate characteristic of deserts of the subtropical zone. average temperature July varies from 25 to 35 C and above. The average temperature in January is 5-15 C and more. The average annual precipitation is no more than 300 mm.

Semi-deserts occupy an intermediate position:
- between zones of deserts and steppes in temperate and subtropical zones;
- between desert and savannah zones in the tropical zone.

Temperate semi-deserts are characterized by a dry continental climate with annual precipitation usually not exceeding 300 mm. Surface flow is small, and rivers usually dry up during the dry season. The vegetation of semi-desert zones is usually sparse with a predominance of grass-wormwood communities, perennial grasses and shrubs.

Semi-deserts of tropical and subtropical zones
The climate is continental, summers are hot (air temperature 20–30 °C, in some places up to 50 °C), winters are cool, air temperatures in the mountains can drop to 0 °C. Precipitation is 200–250 mm per year, in the mountains – up to 400–500 mm. Surface runoff is insignificant and there are few permanent rivers.

Despite the fact that its very name “desert” comes from words such as “empty”, “emptiness”, this amazing natural object filled varied life. The desert is very diverse: in addition to the sand dunes that our eyes usually draw, there are saline, rocky, clayey, and also snowy deserts of Antarctica and the Arctic. Given the snowy deserts of this natural area belongs to one fifth of the entire surface of the Earth!

Geographical object. The meaning of deserts

home distinguishing feature deserts mean drought. Desert topography is very diverse: island mountains and complex highlands, small hills and stratified plains, lake depressions and dried out centuries-old river valleys. The formation of desert relief is greatly influenced by wind.

People use deserts as pastures for livestock and areas for growing some crops. Plants for feeding livestock develop in the desert thanks to the horizon of condensed moisture in the soil, and desert oases, flooded with sun and fed by water, are extremely favorable places for growing cotton, melons, grapes, peach and apricot trees. Of course, only small desert areas are suitable for human activity.

Characteristics of deserts

Deserts are located either next to mountains or almost on the border with them. High mountains prevent the movement of cyclones, and most of the precipitation they bring falls in the mountains or foothill valleys on one side, and on the other side - where the deserts lie - only small remnants of rain reach. The water that manages to reach the desert soil flows through surface and underground watercourses, collecting in springs and forming oases.

Deserts are characterized by different amazing phenomena, which are not found in any other natural area. For example, when there is no wind in the desert, tiny grains of dust rise into the air, forming the so-called “dry fog.” Sandy deserts can “sing”: the movement of large layers of sand generates a high and loud slightly metallic sound (“singing sands”). Deserts are also known for their mirages and terrible sandstorms.

Natural areas and types of deserts

Depending on the natural areas and type of surface, there are the following types of deserts:

• Sand and sand-crushed stone. They are distinguished by great diversity: from chains of dunes devoid of any vegetation to areas covered with shrubs and grass. Traveling through the sandy desert is extremely difficult. Sands do not occupy the largest part of deserts. For example: the sands of the Sahara make up 10% of its territory.

• Rocky (hamads), gypsum, gravelly and gravelly-pebble. They are combined into one group according to a characteristic feature - a rough, hard surface. This type of desert is most common in Globe(Saharan hamadas occupy 70% of its territory). Succulents and lichens grow in tropical rocky deserts.

• Salt marshes. In them, the concentration of salts prevails over other elements. Salt deserts can be covered with a hard, cracked crust of salt or a salt bog that can completely “suck in” a large animal and even a person.

• Clayey. Covered with a smooth clay layer stretching for many kilometers. They are characterized by low mobility and low water properties (the surface layers absorb moisture, preventing it from passing deeper, and quickly dry out during the heat).

Desert climate

Deserts occupy the following climatic zones:

• temperate (Northern Hemisphere)
• subtropical (both hemispheres of the Earth);
• tropical (both hemispheres);
• polar (ice deserts).

Deserts have a continental climate (very hot summers and cold winters). Precipitation falls extremely rarely: from once a month to once every few years and only in the form of showers, because... small precipitation does not reach the ground, evaporating while still in the air.

Daily temperature in a given climatic zone varies greatly: from +50 o C during the day to 0 o C at night (tropics and subtropics) and to -40 o C (northern deserts). Desert air is particularly dry: from 5 to 20% during the day and from 20 to 60% at night.

The largest deserts in the world

Sahara or Queen of the Desert- the largest desert in the world (among hot deserts), the territory of which occupies over 9,000,000 km 2. Located in North Africa, it is famous for its mirages, which occur here on average 150 thousand per year.

Arabian desert(2,330,000 km 2). It is located on the territory of the Arabian Peninsula, also covering part of the land of Egypt, Iraq, Syria, and Jordan. One of the most capricious deserts in the world, known for particularly sharp fluctuations in daily temperature, strong winds and dust storms. From Botswana and Namibia to South Africa it extends over more than 600,000 km 2 Kalahari, constantly increasing its territory due to alluvium.

Gobi(more than 1,200,000 km 2). It is located in the territories of Mongolia and China and is the largest desert in Asia. Almost the entire desert territory is occupied by clay and rocky soils. In the south of Central Asia lie Karakum(“Black Sands”), occupying an area of ​​350,000 km 2.

Victoria Desert- occupies almost half the territory of the Australian continent (over 640,000 km 2). Famous for its red sand dunes, as well as a combination of sandy and rocky areas. Also located in Australia Great Sandy Desert(400,000 km 2).

Two South American deserts are very noteworthy: Atacama(140,000 km 2), which is considered the driest place on the planet, and Salar de Uyuni(more than 10,000 km 2) is the largest salt desert in the world, whose salt reserves amount to more than 10 billion tons.

Finally, the absolute champion in terms of territory occupied among all the world’s deserts is Ice desert Antarctica(about 14,000,000 km 2).

Even the word “desert” itself evokes associations of emptiness and lack of life, but for the people who live on these lands, it seems beautiful and unique. The natural desert zone is a very complex territory, but it is alive. There are sandy, clayey, rocky, saline and snowy (yes, in the Arctic and Antarctica there is an Arctic desert) deserts. The most famous is the Sahara, it is also the largest in area. In total, deserts occupy 11% of the land, and if you count Antarctica - more than 20%.

Look geographical position natural zone of deserts on the map of natural zones.

Deserts are located in the temperate zone of the Northern Hemisphere and the subtropical and tropical zones of the Northern and Southern Hemispheres (they are characterized by special moisture conditions - the amount of precipitation per year becomes less than 200 mm, and the moisture coefficient is 0-0.15). Most deserts were formed on geological platforms, occupying the most ancient land areas. Like other landscapes of the Earth, deserts arose naturally, thanks to the peculiar distribution of heat and moisture over the earth's surface. In simple words, deserts are located in places that receive very little or no moisture. The reasons for this are the mountains that close the deserts from the oceans and seas or the proximity of the desert to the equator.

The main feature of semi-desert and desert lands is drought. Dry, arid zones include lands where the life of people, plants and animals is completely dependent on it. Arid lands make up almost a third of the planet's total land mass.

The relief of the desert zone is very diverse - complex highlands, small hills and island mountains, strata plains, ancient river valleys and closed lake depressions. The most common are aeolian landforms, which were formed under the influence of wind.

Sometimes the territory of deserts is crossed by rivers (Okavango - a river flowing into the desert, Yellow River, Syr Darya, Nile, Amu Darya, etc.), there are many drying up watercourses, lakes and rivers (Chad, Lop Nor, Air).

Soils are poorly developed - water-soluble salts predominate over organic substances.
Groundwater is often mineralized.

Features of the climate.

The climate in deserts is continental: winters are cold and summers are very hot.

Rain falls once a month or only once in several years, in the form heavy downpours. Small rains simply do not reach the surface of the earth, evaporating under the influence of high temperature. The deserts of South America are recognized as the driest areas in the world.

More deserts receive the bulk of their precipitation in spring and winter, and only some deserts maximum amount precipitation falls in the summer in the form of showers (in big deserts Australia and Gobi).

The air temperature in this natural area can fluctuate greatly - during the day it rises to +50°C, and at night it drops to 0°C.
In the northern deserts, winter temperatures drop to -40 °C.

One of the most important features is the dryness of the air - during the day the humidity is 5-20%, and at night within 20-60%.

Great importance The winds play in the deserts. Each of them has its own name, but they are all hot, dry, carrying dust and sand.

The sandy desert is especially dangerous during a hurricane: the sand turns into black clouds and obscures the sun, the wind carries the sand over long distances, destroying absolutely everything in its path.
Another feature of deserts are mirages created by sun rays, which, when refracted, create very amazing pictures on the horizon.