Why is it cold in the desert at night: types of deserts, features. Winter in the Desert Desert Climate Report

Winter in deserts, although it is warmer than in the semi-desert zone, it is still unusually cold for these low latitudes. average temperature January 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 region, the transition of the average daily air temperature through 10° occurs on April 11, and already a decade later or a little later, the transition of the average daily air temperature through 15° occurs in the same place. In terms of its temperature conditions (16-20°), May in the zone resembles the height of summer in central Russia - July. Moderate positive air temperatures in spring are combined with an annual maximum atmospheric precipitation, which in the north of the zone falls in May, in the south – in April.

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 animal world. For some desert inhabitants, spring is the only period of active life in the year. So, 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 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 the deserts of the temperate zone 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, characterized not only by 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 over 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, at low air temperatures, 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 zones of the USSR / F.N. Milkov. - M.: Mysl, 1977. - 296 p.

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 - 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 Northern Hemisphere and subtropical and tropical zones 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, 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 of heavy downpours. Small rains simply do not reach the surface of the earth, evaporating under the influence of high temperature. Deserts are the driest areas in the world South America.

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 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 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 the sun's rays, which, when refracted, create very amazing pictures on the horizon.

The desert climate is characterized by hot summers and cold winters. Average annual temperature varies from +16°C in the northern part to +20°C in the south of the zone. Summer temperatures in western and eastern parts do not differ significantly, they are 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 a frosty period (subtropical), temperate climates with a cold season, hot desert climates, cold desert climates, cold climates with temperate summers, cold climates without warm seasons. For climate groups, numerical characteristics of temperature and precipitation regimes are indicated. 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 falling during the year; 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 in total 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 greatly disturbed by humans, subject to fires, logging, and heavy and varied grazing pressure from sheep, goats, 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 ones coniferous forests under similar environmental conditions. The type of dominant species that determines the nature of leaf litter and chemical composition organic matter soil, significantly affects the species diversity of terrestrial plant communities. [ ...]

The influence of more or less air humidity on animal organism may 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 big amount precipitation and high air humidity are more suitable for the development of dairy cattle breeding (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 with high humidity causes catarrh respiratory tract and intestines, especially in representatives of breeds unaccustomed to such a climate (for example, in steppe sheep when they are transferred to damp areas). In addition, in humid climates, the coat and quality of sheep's wool 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.

Today we will continue our acquaintance with the natural areas of our planet. The theme of our excursion will be the places where camels slowly walk, and the wind and the scorching sun are the undivided masters. We'll talk about deserts.

Here, among the sand and heat, there is its own flora and fauna, people live and work. What are features this zone?

Where are the deserts

Deserts are areas with a continental climate and sparse vegetation. Such places can be found on all continents, with the exception of Europe. They extend across the temperate zone of the Northern Hemisphere and the subtropics and tropics of both hemispheres.

The largest deserts are the Sahara, Victoria, Karakum, Atacama, Nazca, and the Gobi Desert.

Russian deserts are located in the east of Kalmykia and in the south of the Astrakhan region.

Climate Features

The main features of the climate of this zone are high daytime temperatures and extreme dry air. During the day, the water vapor content in the atmosphere is 5–20%, which is several times lower than normal. The driest deserts are the deserts of South America. The main reason - almost complete absence of rain. In some places they occur no more than once every few months or even every few years. Sometimes heavy rainfall falls on the dried, heated ground, but instantly evaporates without having time to saturate the soil.

It is often observed in these places "dry rain" Ordinary raindrops fall from the forming rain clouds, but when they collide with heated air, they evaporate without ever reaching the ground. Precipitation in the form of snow is very rare here. Only in some cases does the snow cover reach a thickness of more than 10 cm.

In this natural zone, daytime temperatures can rise to +50°C, while at night they can drop to 0°C. In the northern regions, the thermometer can drop to minus 40 °C. For these reasons, the climate of deserts is considered continental.

Often residents and tourists witness amazing optical phenomena - mirages. At the same time, tired travelers see in the distance oases with life-giving moisture, wells with drinking water... But all this is an optical illusion caused by the refraction of sunlight in the heated layers of the atmosphere. As these objects approach, they move away from the observer. You can get rid of these optical illusions by starting a fire. The smoke creeping along the ground quickly dispels this obsessive vision.

Relief features

Most of the desert surface is covered with sand and the strong wind becomes the “culprit” of sandstorms. At the same time, they rise above the surface of the earth huge masses of sand. The sandy curtain erases the horizon line and obscures the bright sunlight. Hot air mixed with dust makes breathing difficult.

After 2-3 days the sand settles. And the renewed surface of the desert appears before the eyes of those around you. In some places, rocky areas are exposed, or, conversely, new dunes appear against the backdrop of frozen sand waves. The relief of deserts contains small hills, alternating with plains, ancient river valleys and depressions from once existing lakes.

Characteristic of deserts light soil color, thanks to the lime accumulated in it. Soil surface areas containing an excess amount of iron oxides have a reddish color. The fertile layer of soil - humus is almost absent. In addition to sandy deserts, there are zones with rocky, clayey and saline soil.

Vegetable world

In most deserts precipitation occurs in spring and winter. Moistened soil is literally transformed. Within a few days it becomes colored with a wide variety of colors. The duration of flowering depends on the amount of precipitation and the soil of the area. Local residents and tourists come to admire the bright, beautiful flower carpet.

The heat and lack of moisture soon return it to the desert normal look, where only the most resilient plants can grow.

Tree trunks are most often severely curved. The most common plant in this area is saxaul bushes. They grow in groups, forming small groves. However, do not look for shade under their crowns. Instead of the usual foliage, the branches are covered with small scales.

How does this shrub survive in such arid soils? Nature has provided them with powerful roots that go into the ground to a depth of 15 meters. And another desert plant - camel-thorn its roots can reach moisture from a depth of up to 30 meters. The spines or very small leaves of desert plants allow them to use moisture very economically through evaporation.

Among the various cacti that grow in the desert is Echinocactus Gruzoni. The juice of this one and a half meter plant perfectly quenches thirst.

In the South African desert there is a very amazing flower - fenestraria. Only a few of its leaves are visible on the surface of the earth, but its roots are like a tiny laboratory. This is where the production takes place. nutrients, thanks to which this plant even blooms underground.

One can only be amazed at the adaptability of plants to extreme conditions deserts.

Animal world

In the heat of the day, the desert truly seems devoid of all life. Only occasionally do we see a nimble lizard, and some bug hurries about its business. But With the onset of cool night, the desert comes to life. Small and fairly large animals crawl out of their hiding places to replenish food supplies.

How do animals escape the heat? Some bury themselves in the sand. Already at a depth of 30 cm, the temperature is 40°C lower than on the ground. This is exactly how the kangaroo jumper behaves, which manages not to crawl out of its underground shelter for several days. Its burrows contain reserves of grains that absorb moisture from the air. They quench his hunger and thirst.

Close “canine relatives” of jackals and coyotes from the heat Frequent breathing and sticking out your tongue saves you.

The saliva evaporating from the tongue cools these curious animals quite well. African foxes and hedgehogs emit excess heat with their large ears.

Long legs Ostriches and camels help escape from the hot sand, since they are high enough above the ground, and there the temperature is lower.

In general, the camel is more adapted to life in the desert than other animals. Thanks to its wide, calloused feet, it can walk on hot sand without getting burned or falling through. And its thick and dense coat prevents moisture evaporation. The fat accumulated in the humps is converted into water if necessary. Although he can easily live without water for more than two weeks. And these giants are not picky when it comes to food - they chew camel thorn, and twigs of saxaul or acacia are already a luxury in a camel’s diet.

Desert insects “thought of” reflecting the scorching rays of the sun the surface of your body.

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