The desert climate is characterized by hot summers and cold winters. The average annual temperature varies from +16°C in the northern part to +20°C in the south of the zone. Summer temperatures in the western and eastern parts do not differ significantly, amounting to 26-30°C. [...]

Synonym: desert climate with cold winters.[...]

The division of climates into 9 main groups listed below; these 9 groups contain 30 types. Main groups: warm climates without a dry period (equatorial), warm climates with a dry period (tropical), monsoon climates, warm temperate climates without frost period (subtropical), temperate climates with cold seasons, hot desert climates, cold desert climates, cold climates with moderate summers, cold climates without warm seasons. For climate groups indicated numerical characteristics temperature and precipitation regimes. Certain climate types are named geographically according to the areas where they are most pronounced (Bengal climate, Norwegian climate, etc.).[...]

A. z. Irrigated agriculture is typical. A soils are formed in arid climates of deserts, semi-deserts, dry steppes and desertified savannas, where the evaporation of moisture significantly exceeds its supply with precipitation. A-i climate - a dry climate in which the amount of evaporation greatly exceeds the amount of precipitation during the year. atmospheric precipitation; characterized by clear skies, high level condensation, preventing the formation of clouds, large daily temperature fluctuations. Characteristic of deserts and semi-deserts.[...]

Our observations of benthos suggest that plant communities might be more diverse in stable environments. The climate of the Sonoran Desert is distinctly unstable with alternating two wet and two dry periods per year and with high variability total number precipitation in different years. However, some parts of the Soyora Desert are quite rich in species (see Figure 3-10). It turns out that there is instability in this desert natural conditions does not so much limit diversity as it turns into an aspect of the environment to which plants respond with niche differentiation (see Fig. 3-7) and, as a consequence, species diversity. The vegetation of the Middle East has been very significantly disturbed by humans, it has been subjected to fires, logging, strong and varied grazing pressure from sheep, goats, large cattle and camels. But the structure of open forests and shrubs, altered by grazing, is nevertheless very rich in species that have adapted to these disturbances, especially species of annual and bulbous plants. The fact that warm-climate plant communities in Sonora, the Middle East, and elsewhere are so rich in species despite drought and environmental instability suggests that temperature, rather than moisture or stability, is the major factor that determines the species diversity of vascular plants. One more observation about terrestrial plant communities can be mentioned, namely, broad-leaved deciduous forests are, on average, noticeably richer in species than evergreen coniferous forests under similar environmental conditions. The type of dominant species that determines the nature of leaf litter and chemical composition soil organic matter, significantly affects the species diversity of terrestrial plant communities.[...]

The influence of greater or less air humidity on an animal organism can be expressed in some changes in metabolism and the acquisition in the process of evolution of a number of adaptations to climate characteristics. A dry climate is more favorable for the body. The healing effect of mountain, steppe and semi-desert air is partly explained by its low humidity. The dry climate has a particularly beneficial effect on the wool of sheep (merino sheep breeding); on the strength, energy and performance of horses (for example, Eastern, Arabian, Akhal-Teke). Over the centuries, animals of dry climates (desert and semi-desert zones) have developed exceptional adaptation to these conditions (camel, antelope, some breeds of sheep, donkeys, etc.). Countries with high rainfall and high air humidity are more suitable for the development of dairy farming (forage crops and pasture plants grow well here). However, excessive air humidity has a detrimental effect on the health of animals, as well as on some types of their productivity. Animals living in low, damp places are more often exposed to pulmonary, helminthic and some other diseases. Low temperature at high air humidity it causes catarrh of the respiratory tract and intestines, especially in representatives of breeds unusual for such a climate (for example, in steppe sheep when they are transferred to damp areas). Moreover, in conditions humid climate The coat and wool quality of sheep often deteriorates.[...]

Evaporative geochemical barriers / are areas where an increase in concentration chemical elements occurs as a result of evaporation processes. They are most common in regions with arid climates (deserts, dry steppes and savannas), but are also found in black soil steppes and even in the taiga and tundra. However, in this case, during the rainy period, the soil is washed out and the abnormal concentrations of chemical elements on the evaporation barriers may disappear.[...]

Anthropogenic activity significantly influences climatic factors, changing their regimes. The destruction of forests and other vegetation, the creation of large artificial reservoirs on former land areas increases the reflection of energy, and dust pollution, for example, of snow and ice, on the contrary, increases absorption, which leads to their intensive melting. Thus, the mesoclimate can change dramatically under human influence: it is clear that the climate of North Africa in the distant past, when it was a huge oasis, was significantly different from the climate of the Sahara Desert today.

Geography

20% of the earth's surface is desert. The idea that the desert is a place where there is a lot of sand and is always very hot does not correspond to reality. Most deserts are rocky, covered with flat gravel. With temperature, too, not everything is as is commonly believed. Very high daytime temperatures can drop below zero at night.

Temperate deserts occupy vast areas in the interior of Europe and Asia. From the Caspian Sea through Central Asia to southern regions The Gobi almost completely covers the flat areas. The desert zone is located east of the Caspian Sea between 34° and 48° N. w. The total area of ​​the CIS deserts is 3 million km 2. The relief of deserts is predominantly flat. On the territory of the CIS countries, the largest deserts are the Karakum and Kyzylkum, the area of ​​which is 350 thousand and 300 thousand km, respectively.

IN North America deserts occupy intermountain depressions in the west of the continent.

Subtropical and tropical desert located in western India, Pakistan, Iran, in the central part of the Asia Minor peninsula,

In Africa there are deserts - in the north of the continent - the Sahara, in the southwest - the Namib.

In South America - in northern Chile and northwestern Argentina.

In Australia - the central and northern parts of the continent.

The largest desert in the world is the Sahara (7 million km), located in North Africa. The Gobi and Libyan deserts occupy 2 million km each. Of the semi-desert areas of the world, the largest is the South African Kalahari, its territory is about 1 million km.

Currently, the area of ​​all deserts is constantly increasing. The Sahara is increasing the fastest. Every year its southern border advances by almost 50 km.

Deserts occur where precipitation is less than 80 mm per year. The main reserves of water are located in the soil at considerable depth.

Summers are hot with average temperatures warm months up to 30-40° and with a maximum of up to 58" (Arabia). The soil heats up to +70 "C. Large daily and annual amplitudes of air and soil temperatures are characteristic. In summer, temperatures close to 0° are often observed at night, and in winter frosts are observed even in the Sahara.

Most deserts are characterized by strong winds(over 10 m/sec), often having a constant direction (Afghan, Shamsin).

Desert climate Central Asia sharply continental, dry. Annual precipitation is less than 200 mm. Evaporation is 7-10 times higher than the annual amount of precipitation. Number sunny days reaches 200 per year. Relative humidity during the summer months in daytime 10% or less, at night - up to 25%. In winter, northeastern winds predominate in deserts, and in summer, northwestern winds.

In summer, the average air temperature in the north of the zone reaches +25...+29° C, in the south - up to +32° C. Maximum daytime temperatures can approach +45...+50° C. The soil heats up to +70° C .

Winter in the desert is warmer than in the semi-desert zone, but at times air temperatures can drop to - 25... - 30 ° C. Average temperature January in the north of the desert zone - 12 ° C, in the south - about zero. The height of the snow cover is no more than 10 cm. Snow is not found in the south. Most of the annual precipitation falls in spring.

There are almost no purely mechanical obstacles to movement across rocky deserts; all difficulties are related to the climate. Travel to sandy deserts really difficult. Sand is still not asphalt, but after our off-road driving you will successfully cope with this problem. I advise you to pay attention to your shoes.

Despite such a harsh climate, even the Sahara is inhabited, although sparsely. Vegetation does not form a continuous cover, in some places it is completely absent. There are many ephemeral plants, perfectly adapted to desert conditions. Their seeds germinate almost a day after rain falls. Perennial xerophytes are widely developed, in which a dense network of long roots extracts moisture from great depths. Some plants are adapted to storing large reserves of water in their bodies - cacti, milkweed, etc.

The desert fauna is characterized by relatively large ungulates and rodents: antelopes, wild horses, kulans, ground squirrels, gerbils, jerboas, etc. There are quite a lot of reptiles (lizards, snakes and turtles), insects (diptera, hymenoptera) and arachnids (phalanxes, tarantulas) in the desert , Scorpios).

I did not have to eat pasture in the desert. In African deserts, an oasis with a grove of date palms can be an salvation. The Taureg, who have lived in the Sahara for thousands of years, have learned to make do with a handful of dried dates a day, while walking up to 50 km under the sun. I don’t know how they manage to do this, probably, if you train for 500 years in a row, then you will be able to do the same.

IN Central Asia dates don't grow. But, if you believe the Bible, then the righteous, having retired to the desert, ate grasshoppers (locusts). So practice catching grasshoppers or carefully consider each crossing in the desert.

Life in the desert concentrates near water sources - rivers, canals, springs, artesian wells, wells, filling wells or in mining sites. The most likely encounter is with shepherds. It is possible to find the camp using fresh prints car tires on the ground, in the tracks of ungulates and their droppings. Sheep grazing is usually carried out at a distance not exceeding a daily journey from a water source (well, well).

In the desert, death is most likely from dehydration, heat and sunstroke, and rarely from bites poisonous snakes and arachnids.

Long-term survival in summer in the absence of significant supplies of fresh water is impossible!

Deserts are one of the most interesting places on the planet, which is not at all surprising. These usually barren areas are home to rare species animals and plants, they have unique features in the matter natural characteristics. These natural areas seem mysterious and mystical to many people. It is known that in some deserts the weather changes dramatically: the temperature drops or rises extremely in short periods of time. Why is it cold in the desert at night? Let's find out the main reasons.

Desert types

Before analyzing the specific reasons why deserts are cold at night, it is important to identify the four main types of desert terrain. There are hot and dry, coastal and cold deserts. Each of these types of natural areas has special weather conditions, only hot and dry deserts are subject to the aforementioned extreme temperature changes.

What's happening?

Hot and dry deserts are typically found in the southwestern United States, South Asia, South America and Australia. These deserts can experience extreme temperature changes, with maximums reaching +44-49°C. While minimum temperature may be -18 °C. So why is it cold in the desert at night?

A notable feature of hot and dry deserts is that they are not characterized by dense vegetation. This results in the area not having enough plants and trees to absorb sunlight and retain heat. In other words, when the sun sets and is no longer a source of heat, there is nothing in the desert to keep it warm, since that is the main job of plant life.

Why is it cold at night in hot deserts?

Hot, dry deserts experience concentrated precipitation that usually occurs between longer periods of no precipitation. In some seasons, such as winter, it is rare it's raining in hot and dry deserts. In some desert areas, annual rainfall is less than 1.5 centimeters. This results in a lack of humidity in the air. Humidity is necessary to block the sun's heat, without it the temperature can reach +49°C, as mentioned earlier. This also means that the lack of humidity means that the heat that is present in the desert air during the day is not retained at night. This results in extreme temperature changes. This is why the desert is cold at night.

Due to the lack of plant life and moisture, it is not surprising that hot and dry deserts can lose twice as much heat at night as similar non-desert natural areas.

Not all deserts cool at night. In addition, at certain times of the year the temperature difference may decrease. The air in deserts does cool incredibly quickly, but only if there is no cloud cover (clouds act like a blanket, trapping heat), there is no wind and the air humidity is low. For example, Dubai is essentially a desert on the coast. Deserts located close to the sea certainly suffer from temperature changes, but the difference between day and night indicators is not critical.

But deserts, which are far inland, tend to have higher temperature fluctuations, but even in summer the nights there are never too cold.

Bottom line

Thus, the question of why it is very cold in the desert at night is partially relevant. However, many people mistakenly believe that extreme temperature changes are common in all desert areas, when in reality this is far from the case. The most important factor in this matter is also the geographical location factor.

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 location 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 earth's surface heat and moisture. 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, stratified plains, ancient river valleys and closed lake depressions. The most common are aeolian landforms, which were formed under the influence of wind.

Sometimes the desert territory 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 of heavy downpours. Small rains simply do not reach the surface of the earth, evaporating under the influence of high temperatures. 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 quantity precipitation falls in the summer in the form of showers (in the large deserts of Australia and the 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 there is dry air - during the day the humidity is 5-20%, and at night within 20-60%.

Great value 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.

Winter in deserts, although it is warmer than in the semi-desert zone, it is still unusually cold for these low latitudes. The average January temperature in the north of the zone is about -12°, in the south – close to 0°, the average absolute minimum air temperature is –35-20°. Lake Balkhash and the Aral Sea are frozen in winter; Freeze-up lasts 2.5-3.0 months at the mouths of the Amu Darya and Syrdarya rivers. Snow cover with a height of about 10 cm lies for 100 days in the north of the zone and 20-30 days in the southwest. Little snow and short duration of snow cover make it possible to graze livestock in deserts in winter. The non-grazing period for sheep in the deserts of Kazakhstan lasts only 30-60 days, and in the Central Asian deserts it is practically absent, except for the relatively rare days with ice and snowstorms here.

Spring- a season of the year that refutes the usual ideas about the desert. At this time, there is a rapid increase in air temperature, unusual for other zones. In the Kzyl-Orda area, the crossing of the middle daily temperature air temperature through 10° occurs on April 11, and already after a decade or a little later the transition of the average daily air temperature through 15° occurs in the same place. May in the zone in its temperature conditions (16-20°) resembles the height of summer middle zone Russia - July. Moderate positive air temperatures in spring are combined with the annual maximum precipitation, which occurs in May in the north of the zone and April in the south.

Atmospheric precipitation, together with winter reserves of soil moisture, is sufficient for short-term but lush development of vegetation. It is at this time that there is an outbreak of vegetation of ephemerals and ephemeroids, especially characteristic of sandy and foothill loess deserts. Becomes very active fauna. For some desert inhabitants, spring is the only period of active life in the year. For example, the steppe tortoise is active only from March to May; after the ephemerals burn out, it buries itself in the ground and lies there until the next spring. The sand squirrel leads a similar lifestyle.

It is significant that the lambing of the goitered gazelle and domestic Karakul sheep coincides with the development of ephemeral-ephemeroid vegetation. At the same time, the growth of Karakul lamb is very intense in the first month. “The meaning of this phenomenon is that a lamb in the desert must be prepared for the early dry summer, for eating dry, hard grasses in the summer, and must have time to gain a sufficient supply of fat.”

Summer in temperate deserts it is even hotter, sunny and dry than in the semi-desert zone. The average temperature in July is about 25-29°, on some days the air temperature in the shade rises above 40°, and the surface of the bare soil heats up to 70°. The hot period in the zone is characterized by stability and duration: the number of days with an average daily air temperature above 20° in the north is 90, in the south - 140. The entire territory of the zone in summer serves as an arena for the formation of local continental tropical air, which differs not only high temperatures, but also very low humidity and high dust levels.

The sweltering heat is aggravated by the insignificant amount of precipitation, the amount of which quickly decreases in a southerly direction. During all three summer months, 30 mm of precipitation falls in Irgiz, 19 mm in Kazalinsk, and 11 mm in Turkestan. For comparison, let us point out that Moscow, with its moderate warm summer receives 192 mm of precipitation during the same period. Due to an acute lack of moisture, ephemerals and ephemeroids disappear from the grass cover even before the beginning of summer, and the most undemanding shrub wormwood and solyanka, which are in a state of semi-dormancy, stop growing. At the beginning of summer, cotton budding occurs, in July it begins to flower, and at the end of August - beginning of September, ripening occurs.

Autumn the first half is very reminiscent of summer: in September, as in previous months, hot and dry cloudless weather prevails, favorable for the ripening and harvesting of cotton and fruit crops. In the southern half of the zone, the transition of the average daily temperature through 15° occurs around October 1. In the second half of autumn, cloudiness increases, the amount of precipitation increases, which low temperatures air creates conditions for repeated vegetation (greening) of many plants. The first frosts in most of the zone appear in October.

Literature.

1. Milkov F.N. Natural areas USSR / F.N. Milkov. - M.: Mysl, 1977. - 296 p.