DUSTY (SANDY) LANDSCAPE. The transfer of dust, dry earth or sand only near the earth's surface, to a height of less than 2 m (not higher than the eye of the observer). [...]

Dust storms - associated with the transfer of large amounts of dust or sand raised from the earth's surface by a strong wind; particles of the upper layer of dried up soil, not held together by vegetation. They can be caused by both natural (drought, dry winds) and anthropogenic factors (intensive plowing of land, overgrazing, desertification, etc.). Dust storms are typical mainly for arid areas (dry steppes, semi-deserts, deserts). However, sometimes dust storms can be observed in forest-steppe regions. In May 1990, a strong dust storm was noted in the forest-steppes of southern Siberia (the wind speed reached 40 m / s). Visibility decreased to several meters, power transmission poles were overturned, powerful trees were turned up, and fires were blazing. In the Irkutsk region, on 190 thousand hectares, agricultural crops were damaged and killed. [...]

Dust storms occur with very strong and prolonged winds. The wind speed reaches 20-30 m / s and more. Most often, dust storms are observed in arid regions (dry steppes, semi-deserts, deserts). Dust storms irrevocably carry away the most fertile topsoil; they are able to dispel in a few hours up to 500 tons of soil from 1 hectare of arable land, negatively affect all components of the natural environment, pollute the air, water bodies, negatively affect human health. [...]

A DUST STORM is a phenomenon in which a strong wind (speed reaches 25-32 m / s) raises a huge amount of solid particles (soil, sand), which are blown out in places not protected by vegetation and swept into others. P. b. serves as an indicator of improper agricultural practices, neglect of maintaining ecological balance. [...]

Dust storms are one of the most dangerous meteorological phenomena for agriculture. They arise under the influence of both natural and anthropogenic factors and are often associated with forms of agriculture that do not correspond to a given climatic zone. Many areas of the steppe zone of Russia are affected by dust storms. [...]

Dust storms are most often observed in the spring, when the wind increases, and the fields are plowed up or the vegetation on them is still poorly developed. There are dust storms in the steppes at the end of summer, when the soil dries up, and the fields, after harvesting early spring crops, begin to plow up. Winter dust storms are relatively rare. [...]

Dust storm - the transfer of dust and sand by strong and prolonged winds blowing out the upper layers of the soil. A typical phenomenon in plowed steppes, as well as in semi-deserts and deserts of the USA, China and other zones. [...]

Dust storms occur mainly during the cold season. This most active and dangerous type of deflation is facilitated by strong fluctuations in atmospheric pressure in vast areas relatively close to each other, low soil moisture, and the absence of snow cover on them. [...]

Dust (black) storm is a very strong wind with a speed of more than 25 m / s, carrying a huge amount of solid particles (dust, sand, etc.) blown out in places not protected by vegetation and swept into others. A dust storm, as a rule, is a consequence of disturbing the soil surface by improper agricultural practices: reduction of vegetation, destruction of the structure, desiccation, etc. [...]

A storm is a type of hurricane, but has a lower wind speed. The main causes of casualties in hurricanes and storms are the injury of people by flying debris, falling trees and building elements. The immediate cause of death in many cases is asphyxiation from pressure, severe injuries. Among the survivors, there are multiple soft tissue injuries, closed or open fractures, craniocerebral injuries, and spinal injuries. Wounds often contain deeply penetrated foreign bodies (soil, pieces of asphalt, glass shards), which leads to septic complications and even gas gangrene. Dust storms are especially dangerous in the southern arid regions of Siberia and the European part of the country, as they cause erosion and weathering of the soil, carryover or backfilling of crops, exposure of roots. [...]

Dust storms at high wind speeds and after a long dry period are a source of innumerable disasters for the entire South-East and South of the USSR. The most destructive storms in the area under consideration were in 1892, 1928, 1960 [...]

Dust storms have wreaked havoc on land cover and farming in the southern Great Plains region. They were the last warning to Americans about the disastrous state of the US soil cover. Therefore, in 1935, the Soil Conservation Service was organized at the federal level, headed by an outstanding specialist in the field of soil science, H. Bennett. A survey carried out during this period showed that nationwide measures are needed to save soil fertility. From 25 to 75% of the topsoil was destroyed on an area of ​​256 million hectares. [...]

DUST STORM. The transport of large amounts of dust or sand by strong winds is a typical phenomenon in deserts and steppes. Desert surfaces, free from vegetation and arid, are a particularly effective source of atmospheric dust. The visibility range at P. B. is significantly reduced. In the plowed steppes, dust storms cover crops, blow out the upper layers of the soil, often together with seeds and young plants. Dust can then fall out of the air in quantities of millions of tons over large areas far (sometimes thousands of kilometers) from the source of the dust (see dust fallout). PB are common in the USA, China, the United Arab Republic, in the Sahara and Gobi deserts, in the USSR - in the deserts of the Turan lowland, in the Ciscaucasia and southern Ukraine. [...]

Dust storms are a formidable and dangerous manifestation of wind erosion. It occurs on vast areas of poorly protected surface of the earth under high-speed winds and causes enormous damage to the national economy and irreparable damage to soil fertility, invaluable in money. [...]

These dust storms interrupted the normal course of life in cities and on farms, interrupted classes in schools, caused new types of diseases, such as "dust pneumonia" and others, and posed an unexpected and serious threat to the existence of the population. The area of ​​arable and grazing land affected by wind erosion in the United States in the Great Plains area exceeds 90 million hectares. So dramatically affected the consequences of the capitalist use of natural resources in this country. [...]

Dust storms mean a meteorological phenomenon in which a strong or moderate wind from the surface of the earth, free from vegetation or with a poorly developed herbaceous cover, rises into the air dust, sand or fine soil particles, impairing visibility within the range from several meters to 10 km. Dust storms occur during dry periods without rain, often at the same time as dry winds. The distribution of the number of days with dust storms depends to a large extent on the relief. The largest number of days with a dust storm is observed in the central and eastern regions of the territory. Their number per year averages 11-19 days. On the plains of the Western Ciscaucasia, the number of days with dust storms decreases to 1-4 per year. In floodplains of rivers, valleys and hollows, where the soil is soddy and the wind is somewhat weakened, the number of days with dust storms is reduced. There are no dust storms in the mountains and on the Black Sea coast of the Caucasus south of Novorossiysk. Most often, dust storms are observed in summer and spring. [...]

In 1969, dust storms were in a large area in the European part of Russia - in the North Caucasus and the Volga region. In the Stavropol Territory, MN Zaslavsky observed plots of arable land where a layer of soil 10-20 cm thick was blown out. During a dust storm in 1969 in the European part of Russia, winter crops died on a huge area, measured in the first million hectares. [... ]

With local dust storms in Kazakhstan, b0 ranges from 50 to 100 m. Consequently, 5 should be 500-1000 m. [...]

The recurrence of dust storms is most strongly influenced by the influence of the underlying surface and the degree of protection of the territory. A prerequisite for dust storms is the presence of dry fine earth, sand or other weathering products. In such areas, a slight increase in wind (up to 5-6 m / s) is sufficient for a dust storm to occur. Dust storms are harmful for grazing and keeping livestock in distant pasture areas. [...]

By the time of the dust storm on April 20, early vegetable crops were sown on a part of this area - carrots, onions, sorrel; the sowing is rolled with a smooth roller. A part of the uncultivated area was only buried, not rolled in. A dust storm from the rolled-in part of the site carried out a layer of soil 4-5 cm along with seeds, threw it through an adult forest belt. The non-rolled part of the site did not erode. In the 0-5 cm soil layer before the start of the dust storm, there was the following number of aggregates (in%). [...]

1.11

In the winter of 1969, strong dust storms were observed due to both meteorological conditions (eastern hurricane winds) and agrotechnical factors. In some areas of the Lower Don, a 2-5 cm layer of soil was demolished from the surface of arable land with crops, and in the Stavropol Territory - a soil layer up to 6-8 cm or more. Formed powerful snow-earthen ramparts (up to 25 m wide and more, with a height of up to 2 m) near the forest belts. Winter crops were damaged in the Rostov Region and Krasnodar Territory, respectively, on an area of ​​646 and 600 thousand hectares. However, winter crops and irrigation canals protected by forest belts, especially of the meridional direction, suffered significantly less than in other areas. It has been established that agroforestry and a high level of agrotechnical work are the main methods of protecting soils in steppe regions from dust storms. [...]

Frontal dust storms are shorter (up to 6-8 hours), while dust storms of storm zones can last more than a day. [...]

UV is the maximum wind speed (at the height of the weather vane) during dust storms with a coverage of 20% (see Table 9.3), m / s; go - parameter of the field surface roughness, m. [...]

The enormous significance of this phenomenon can be judged by the fact that after dust storms in 1969 in the Don and Kuban, the height of the dust rolls deposited on mechanical barriers in the Krasnodar Territory sometimes reached 5 m. and bushes, it is difficult to exaggerate the positive role (especially with the development of agriculture on large areas) of forest belts. [...]

In 1957, the data of V.A.Frantsesoia and his co-workers were published on observations of dust storms on ordinary chernozems of the Kustanai region (Frantseson, 1963). The authors selected a layer from 0 to 3 cm from fields of different erosional state and subjected them to structural analysis. As a result, it was concluded that the wind resistance of the soil surface is ensured when the content of 40% lumps larger than 2 mm in diameter, including lumps larger than 10 mm from 10 to 25%. They also noted a high content of aggregates smaller than 1 mm in diameter in the surface layer of eroding fields. The choice of soil-protecting lumps larger than 2 mm in diameter as an indicator of the wind resistance of the soil surface has not been substantiated by any research. According to the structural analysis data available in this work, we divided the fractions into two groups - larger and smaller than 1 mm and calculated the lumpiness indices for fields that were and did not undergo erosion (Table 5). [...]

Naturally, the atmosphere is polluted during volcanic eruptions, forest fires, dust storms, etc. In this case, solid and gaseous substances enter the atmosphere, which are classified as unstable, variable constituents of atmospheric air. [...]

In Chapter 1, we discussed the role of dust emissions from industrial plants, thermal power plants, dust storms and other sources of the smallest particulate matter, dust that enters the atmosphere as a result of human activity, in air pollution. The contribution of technogenic dusting of the atmosphere to albedo changes can be twofold. On the one hand, a decrease in the transparency of the atmosphere increases the reflection and scattering of solar radiation in space. At the same time, dusting of mountain glaciers and snow-covered surfaces reduces their reflectivity and accelerates melting. [...]

Protective forest belts - planting of tree and shrub species in the form of a number of strips, designed to protect farmland, gardens from dry winds, dust storms, wind erosion, to improve the water regime of soil, as well as to preserve and maintain the species diversity of agrocenoses (inhibits mass reproduction of pests) etc. Forest belts play an especially important role in protecting grain crops during dust storms in the arid regions of the country. In 1994, in Russia, forest shelter belts were created on an area of ​​7.2 thousand hectares, and pasture plantations - on an area of ​​28.4 thousand hectares. [...]

Aeolian sediments from the indicated parts of the field, deposited near various kinds of obstacles, contained 88.4%: aggregates smaller than 1 mm in diameter and only 11.6% soil-protective. The fine earth collected in two dust storms in dust collectors consisted of 96.9% of erosion-hazardous soil fractions, and the share of the most aggressive (less than 0.5 mm in diameter) accounted for 81.6%. [...]

The task is to place obstacles on the path of the flow precisely at such distances at which the content of fine earth in the flow does not exceed the permissible value, and then the occurrence of a dust storm will be excluded. [...]

Aerosols (from the Greek - air and German - colloidal solution) are solid or liquid particles suspended in a gaseous medium (atmosphere). Their sources are both natural (volcanic eruptions, dust storms, forest fires, etc.) and anthropogenic factors (thermal power plants, industrial enterprises, processing plants, agriculture, etc.). So, in 1990 in the world, the emission of particulate matter (dust) into the atmosphere amounted to 57 million tons. suspended particles in the atmosphere at 100 global monitoring stations (for the period 1976-1985), it was found that the most polluted cities are Kolkata, Bombay, Shanghai, Chicago, Athens, etc. These artificial aerosols cause a number of negative phenomena in the atmosphere (photochemical smog, decrease in the transparency of the atmosphere, etc.), which is especially harmful to the health of urban residents. [...]

The criteria for assessing green areas in various natural and climatic regions of the country are also ambiguous. So, for example, specific requirements (and, accordingly, assessment methods) are imposed in the zones of forest-steppe and steppes - protection from dust storms and dry winds, soil consolidation, etc. growth, etc. Of course, no less important are the differences in the role that green spaces play in shaping the architectural and artistic appearance of the city. [...]

Under certain conditions, all components of the general circulation of the atmosphere can be accompanied by the phenomenon of wind erosion of soil, which leads to dusting of the atmosphere. In meteorology, the phenomenon of the transfer of soil particles by a strong wind is called a dust storm. The horizontal length of the dust storm is from tens and hundreds of meters to several thousand kilometers, and the vertical one is from several meters to several kilometers. [...]

Of the characteristics of the water regime, the most important are the average annual precipitation, its fluctuation, seasonal distribution, moisture coefficient or hydrothermal coefficient, the presence of dry periods, their duration and frequency, recurrence, depth, time of establishment and destruction of snow cover, seasonal dynamics of air humidity, presence dry winds, dust storms and other beneficial natural phenomena. [...]

Quarantine weeds spread along with the seeds of cultivated plants, which is facilitated by the movement of large volumes of sowing material, food and forage grains within the country and abroad. The most common sources for the spread of quarantine weeds are non-agricultural areas, roads, irrigation and drainage systems, winds, dust storms, etc. [...]

The studies were carried out in island pine plantations in the Minusinsk and Shirinskaya steppes, of which the latter is distinguished by a very severe climate (Fig. 1). The Shirinskaya steppe of Khakassia is characterized by unstable atmospheric humidification with fluctuations in annual precipitation from 139 to 462 mm, as well as a very uneven distribution over the seasons. Constant and rather strong winds lead to dust storms in the winter-spring period, about 30-40 days a year, the wind speed reaches 15-28 m / s ("Formation and properties ...", 1967). The average annual amount of moisture evaporating from the water surface (for Khakassia it is 644 mm) is almost twice the annual amount of precipitation. There are 29 days a year with a relative humidity of about 30%. The greatest dryness of air and soil is observed in spring and early summer (Polezhaeva, Savin, 1974). [...]

Dust, rising from the surface of the earth, consists of small particles of rocks, soil residues of vegetation and living organisms. The sizes of dusty particles, depending on their origin, range from 1 to several microns. At an altitude of 1-2 km from the earth's surface, the content of dust particles in the air is from 0.002 to 0.02 g / m3, in some cases this concentration can increase tens and hundreds of times, during dust storms up to 100 g / m 'and more . [...]

The wind speed regularly changes during the day, along with it, the intensity of the processes of wind erosion of soils also changes. Obviously, the longer the wind, which has a speed higher than the critical one, the greater the loss of soil will be. Typically, the wind speed increases during the day, reaching a maximum by noon, and decreases in the evening. However, it is not uncommon for the intensity of wind erosion to change slightly during the day. So, in the spring of 1969 in the Krasnodar Territory, the strongest dust storms lasted continuously for 80-90 hours, and in February of the same year - up to 200-300 hours. [...]

The winds of the southern, south-western and northern directions prevail (Table 1.7). The percentage of days with calm averages 17-19 with maximums in December-March and August. The average annual wind speed is 3.2-4.3 m / s (Table 1.8) and has a well-pronounced daily variation, determined primarily by the daily variation of air temperature (Table 1.9). Daily fluctuations are more pronounced in the warm period and less in winter and early spring. The maximum wind speed is observed in winter. The average number of days with strong winds is 27-36 (Table 1.10), and the number of days with dust storms does not exceed 1.0 (Table 1.11). [...]

Here are some examples of insulation overlaps that have taken place in recent years both with natural and industrial pollution. In the winter of 1968-69, massive insulation overlaps were observed in the south of the European part of the Soviet Union. At the same time, 57 overlaps occurred in one power system for several days only on 220 kV high-voltage lines with normal insulation, as a result of which the power supply to consumers through these lines was interrupted. The reason for the overlaps is the contamination of insulators with soil dust with a high salt content during a dust storm and subsequent humidification with thick fog and drizzling rain with an increase in the temperature and humidity of the atmospheric air. Normal insulation was used at the outdoor switchgear of a thermal power plant located in the northwestern part of the Soviet Union and operating on shale fuel. Under unfavorable meteorological conditions at this station, insulation overlaps were repeatedly observed during normal operating conditions. In the winter of 1966, after a long frosty period, a sharp warming occurred, as a result of which overlapping of 220 kV disconnectors, assembled from support-rod insulators of the KO-400 C type, occurred. It is possible to point out a number of overlaps that have taken place in recent years near chemical plants in various regions of the Soviet Union under unfavorable meteorological conditions and the impact of an emission torch on insulators. For example, with strong fog and weak wind from the side of a large petrochemical plant, overlapping of external insulation was observed at distances of up to 10 km from the source of pollution. Similar overlaps with consequences of an emergency nature were repeatedly observed abroad. [...]

The Earth's atmosphere is a mechanical mixture of gases called air, with solid and liquid particles suspended in it. For a quantitative description of the state of the atmosphere at certain points in time, a number of quantities are introduced, which are called meteorological quantities: temperature, pressure, air density and humidity, wind speed, etc. ) changes in the state of the atmosphere. Atmospheric phenomena include: precipitation, clouds, fog, thunderstorms, dust storms, etc. The physical state of the atmosphere, characterized by a set of meteorological quantities and atmospheric phenomena, is called weather. For the analysis and forecasting of weather, the values ​​of meteorological values, as well as special weather phenomena, determined at a single point in time at an extensive network of meteorological stations, are applied to geographical maps with conventional signs and numbers. Such maps are called weather maps. The statistical long-term weather regime is called climate. [...]

Irrigation erosion is a type of water erosion. It develops as a result of violation of irrigation rules in irrigated agriculture. The waving of the upper horizons of the soil under the influence of strong winds is called wind erosion, or deflation. During deflation, the soil loses the smallest particles, with which the most important chemicals for fertility are carried out. The development of wind erosion is facilitated by the destruction of vegetation in areas with insufficient atmospheric moisture, excessive grazing, and strong winds. It is most susceptible to sandy loam, as well as fertile carbonate chernozems. During severe storms, soil particles can be carried away from large areas over considerable distances. According to M. L. Iackson (1973), on the planet annually up to 500 million tons of dust enters the atmosphere. It is known from history that dust storms destroyed the unprotected soils of vast agricultural areas in Asia, Southern Europe, Africa, South and North America, and Australia. They are now becoming a national or regional disaster for many states. Losses of soils from wind erosion in the most catastrophic years are up to 400 t / ha. In the USA in 1934, as a result of a storm that broke out in the area of ​​the plowed prairies of the Great Plain, about 20 million hectares of arable land were turned into waste land, 60 million hectares sharply reduced their fertility. According to RP Beasley (1973), in the 1930s there were more than 3 million hectares (about 775 million acres) of highly eroded land in this country; in the mid-1960s, their area decreased slightly (738 million acres), and in the 70s it increased again. In pursuit of profit from the sale of grain, pastures and tinned slopes were plowed up. And this immediately affected the resistance of the soil from scattering. Loss of yield on such soils today is 50-60%. Similar phenomena are found everywhere. [...]

Since 1963, the PAU-2 aerodynamic unit has been used to study erosion processes. This device made it possible to experimentally study the processes of soil erosion by wind. The principle of operation of the device is as follows: over a limited area of ​​the soil surface (in the field or at a stationary above an artificially created area with given roughness parameters), an artificial air flow is created, similar to the natural wind; when the air flow moves over a section of the soil surface, the blowing and transfer of soil material occurs, which is also similar to the natural erosion of the soil by the wind during dust storms; Part of the fine earth carried by the air flow is captured by dust-collecting tubes installed at different heights above the soil surface and deposited in cyclones. The amount of soil material captured by PAH-2 from the surface of the site during the experiment is used to judge the erodibility of this soil (Bocharov, 1963). [...]

A typical desert aerosol consists of 75% clay minerals (35% montmorillonite and 20% kaolinite and illite each), 10% calcite, and 5% each quartz, potassium nitrate and iron compounds limonite, hematite and magnetite with an admixture of some organic substances ... According to line 1a table. 7.1, the annual production of mineral dust varies widely (0.12-2.00 Gt). With altitude, the concentration decreases, so that mineral dust is observed mainly in the lower half of the troposphere to heights of 3-5 km, and over areas of dust storms - sometimes up to 5-7 km. The size distribution of mineral dust particles usually has two maxima in the ranges of the coarse (mainly silicate) fraction r = 1 ... 10 μm, which significantly affects the transfer of thermal radiation, and the submicron fraction r [...]

As with all natural processes, there is a mutual connection between natural disasters. One catastrophe affects another, it happens that the first catastrophe serves as a trigger for the next. The genetic dependence of natural disasters is shown in Fig. 2.4, arrows show the direction of natural processes: the thicker the arrow, the more obvious this dependence. The closest relationship exists between earthquakes and tsunamis. Tropical cyclones almost always cause flooding; earthquakes can cause landslides. Those, in turn, provoke floods. The relationship between earthquakes and volcanic eruptions is mutual: earthquakes caused by volcanic eruptions are known, and vice versa, volcanic eruptions caused by earthquakes. Atmospheric disturbances and heavy rainfall can affect the sliding of the slopes. Dust storms are a direct consequence of atmospheric disturbances. [...]

An admixture of detrital material is represented by feldspars, pyroxenes and quartz. Feldspar, pyroxenes, and montmorillonite come from intraoceanic sources, and in particular the latter, as a result of underwater decomposition of basalts. Terrigenous chlorite comes from areas with the development of rocks of low stages of metamorphism. Quartz, illite and, to a lesser extent, kaolinite are carried out into the ocean, as it is assumed, by high-altitude atmospheric jet streams; the contribution of aeolian material to the composition of pelagic clays is probably from 10 to 30%. The Sahara Desert is a well-studied supplier of clay material to the deep-sea basins of the Atlantic - the material of dust storms in Africa can be traced back to the Caribbean Sea. The aeolian clays of the Indian and North Pacific Ocean were probably formed due to the removal of dust from the Asian mainland; Australia is the source of aeolian material in the South Pacific. [...]

Another factor affecting the soil cover is soil erosion. This is the process of destruction and demolition of soils and loose rocks by water flows and wind (water and wind erosion). Human activity accelerates this process in comparison with natural phenomena by 100-1000 times. Over the last century alone, more than 2 billion hectares of fertile agricultural land, or 27% of agricultural land, have been lost. Erosion carries away, together with water and soil, biogenic elements (P, K, 14, Ca, Mg) in quantities much larger than those introduced with fertilizers. The structure of the soil is destroyed, and its productivity is reduced by 35-70%. The main cause of erosion is improper land cultivation (during plowing, sowing, weeding, harvesting, etc.), leading to loosening and crushing of the soil layer. Water erosion prevails in places of intense rains and when using sprinklers in places where the surfaces of fields and saddles are sloped. Wind erosion is typical for areas with high temperatures, insufficient moisture combined with strong winds. So, dust storms carry away up to 20 cm of the soil layer along with crops.

A 500 km cloud of dust has already reached Sydney, delaying flights. Poor visibility is also seen in other parts of New South Wales.

It will be noted that the state has been experiencing drought since August - strong winds raise dry soil, which caused the formation of a dust storm.

Locals are encouraged to stay indoors, "especially children, the elderly and those with breathing problems." According to doctors, dozens of people have already asked for help with complaints of breathing problems. The number of victims of the disaster is still unknown.

Sydney residents were alerted to the danger a few hours ago, when a dust storm with a front of about 500 km began to approach the city. Many other areas of NSW also report poor visibility due to dust in the air.

Sand storms and their features

A dust storm is a rather dangerous and unpleasant phenomenon in which large masses of dust (sand, soil) are lifted by the wind from the surface of the earth and move at a height of several meters, but in some cases the height can reach a kilometer or even more. From the outside it looks like a wall of dust and sand is moving towards you.

Other names for this phenomenon are "sandstorm" and "duststorm". It is sometimes also referred to as a sandstorm. This is because a strong wind is called a storm. A sandstorm is a type of storm. This should be understood.

Usually, after a dust storm (or even before it), particles of sand and dust are suspended in the air. They do not move anywhere, but simply fluctuate in almost one place, greatly impairing the view at the same time. This phenomenon is called dusty haze (or sand haze).

Causes of the phenomenon

Only two factors are enough for the occurrence of a storm: dry soil and strong wind (usually from 10 m / s and stronger). It's simple: the wind picks up loose particles of sand, dust, soil from the ground, which form a dust storm. This happens most often in deserts and semi-deserts, and it is understandable, because these are the driest regions of the Earth.

Aftermath of dust storms

- Reduced visibility, which greatly affects movement, be it flights or vehicles;

- Difficulty breathing living beings;

- Damage to plants (up to their destruction);

- Destruction of the fertile soil layer;

- Reducing the amount of sunlight reaching the planet's surface.

The largest number of dust storms are observed in the Sahara Desert. It is interesting that earlier they were not very frequent in that area, but since the middle of the last century their number has increased tenfold! If earlier there were ten of them a year, now even hundreds of storms a year are no longer surprising.
However, such a number of them is certainly not normal, as evidenced by the greatly reduced thickness of the upper layer of the soil (the most fertile) in those regions.

Not only are sandstorms a frequent occurrence, but they are also dangerous. Sometimes their strength reaches such an extent that the phenomenon can change the topography of the planet, for example, by moving the dunes in the deserts. Although, in fairness, the relief is changed not only by them, but also by some other phenomena. For example, a sand whirlwind, they are also called dust devils.

But it's worth noting that dust storms can be beneficial as well. After all, the same fertile soil that this phenomenon destroys in one region settles in another. For example, in Hawaii, they are welcome, as dust storms promote the growth of banana crops. And storms also replenish the iron content in the oceans, otherwise there would be a serious lack of iron, which would affect the flora and fauna of the oceans (and this would affect the life of people).

Dust (sand) storm - in the form of the transfer of large amounts of dust (soil particles, grains of sand) by the wind from the earth's surface in a layer several meters high with a noticeable deterioration (usually at a level of 2 m it ranges from 1 to 9 km, but in some cases it can decrease to several hundred and even up to several tens of meters). At the same time, dust (sand) rises into the air and, at the same time, dust settles over a large area. Depending on the color of the soil in a given region, distant objects acquire a grayish, yellowish or reddish tint. It usually occurs when the soil surface is dry and the wind speed is 10 m / s or more.

Often arises in the warm season in and regions. When a certain threshold of wind speed is exceeded (depending on the mechanical composition of the soil and its moisture content), the particles are detached from the surface and transported by way and, causing soil erosion.

Dusty (sandy) drifting - the transfer of dust (soil particles, grains of sand) by the wind from the earth's surface in a layer 0.5-2 m high, which does not lead to a noticeable deterioration in visibility (if there are no other atmospheric phenomena, horizontal visibility at a level of 2 m is 10 km or more ). It usually occurs when the soil surface is dry and the wind speed is 6-9 m / s or more.

Geography

The main distribution area of ​​dust storms is and temperate and tropical climatic zones of both hemispheres of the Earth.

Desert and deserts are the main sources of airborne dust in the area , the smaller contribution is made by, and ... Dust storms in China carry dust into ... Environmentalists believe that irresponsible management of the arid regions of the Earth, for example, ignoring the system, lead to and climate change at the local and global levels.

Term "sandstorm" is usually used in the sense sandstorms, especially in the Sahara, when, in addition to small particles that reduce visibility, the wind also carries millions of tons of larger sand particles over the surface. Term dust storm more refers to the phenomenon of transport of small particles over distances of up to several thousand km, especially when storms "cover" urban areas.

The high frequency of dust storms is noted in and (south), on the coasts, in , in Karakalpakstan and Turkmenistan. In Russia, dust storms are most often observed in, in the east and in.

During long periods of dry weather, dust storms can develop (not annually) in the steppe and forest-steppe zones: in Russia - in,, Tove,,,,, regions, Bashkiria,.., areas, and edge; on - in,,,, areas, in ; in the north, central and east .

At (before a thunderstorm and heavy rain) short-term (from several minutes to an hour) local dust storms can be observed in the summer even in points located in the forest vegetation zone - incl. v and (1-3 days per summer).

Causes of occurrence

With an increase in the force of the wind flow passing over the loose particles, the latter begin to vibrate and then "jump". When repeatedly hitting the ground, these particles create fine dust, which rises in the form of a suspension.

Recent research suggests that the initial grains of sand with the help of friction induces ... The bouncing particles take on a negative charge, which releases more particles. This process captures twice as many particles as predicted by previous theories.Particles are freed mainly due to and the wind. Wind gust fronts may appear due to air cooling after a strong rain or dry ... After passing a dry cold front instability can create a dust storm. In desert areas, dust and sandstorms are most often caused by thunderstorm outflows and increased wind speeds. The vertical dimensions of the storm are determined by the stability of the atmosphere and the weight of the particles. In some cases, dust and sandstorms can be confined to a relatively thin layer due to the effect of temperature inversion. In other cases, dust can rise to a height of 6100 m.

Ways to fight

To prevent and reduce the effects of dust storms, field-protective forest belts, snow and water retention complexes are created, and agrotechnical methods are used, such as grass sowing, and contour plowing.

Environmental impact

Sandstorms can move whole and carry huge amounts of dust, so that the front of a storm can look like a solid wall 1.6 km high. Dust and sand storms coming from the desert also known as, (in Egypt and) and (in).

Most dust storms originate in the Sahara, especially in the trench and in the area of ​​convergence, and ... Over the past half century (since the 1950s), dust storms of the Sahara have increased by about 10 times, causing a decrease in the thickness of the topsoil in, Chad, northern and ... There were only two dust storms in Mauritania in the 1960s, and there are currently 80 storms a year. The amount of dust blown from the Sahara towards the Atlantic Ocean in June five times more than a year ago, which could cool the waters of the Atlantic and slightly reduce activity .

Economic implications

The main damage caused by dust storms is the destruction of the fertile soil layer, which reduces its ... In addition, the abrasive effect damages young plants. Other possible negative effects include: affecting air and road transport; reducing the amount of sunlight reaching the Earth's surface; thermal blanket effect; adverse effects on the respiratory system of living organisms.

Dust can also be beneficial in deposition sites - and receives most of the mineral fertilizers from the Sahara, replenishes the lack of iron in the ocean, dust on helps to grow crops. In the north of China and in the west of the United States, soils with sediments of ancient storms, called , are very fertile, but are also the source of modern dust storms, when the vegetation that binds the soil is disturbed.

Extraterrestrial dust storms

The large temperature difference between the ice shell and warm air at the edge of Mars' south polar cap results in strong winds that raise huge clouds of reddish-brown dust. Experts believe that dust on Mars can play the same function as clouds on Earth - it absorbs sunlight and thereby heats the atmosphere.

Dust storm is a type of dry wind, characterized by strong winds, carrying huge masses of soil and sand particles over long distances. Dusty or sandstorms they cover agricultural land, buildings, structures, roads, etc. with a layer of dust and sand reaching several tens of centimeters. Moreover, the area on which dust or sand falls can reach hundreds of thousands, and sometimes millions of square kilometers.

In the midst of a dust storm, the air is so saturated with dust that visibility is limited to three to four meters. After such a storm, often, where the shoots were green, a desert spreads out. Sandstorms are not uncommon in the vast expanses of the Sahara, the greatest desert in the world. Vast desert areas, where sandstorms also occur, are found in Arabia, Iran, Central Asia, Australia, South America and elsewhere in the world. Sand dust, raised high into the air, makes it difficult for aircraft to fly, covers with a thin layer the decks of ships, houses and fields, roads, airfields. Falling out on the water of the ocean, the dust sinks into its depths and is deposited on the ocean floor.

Dust storms not only raise huge masses of sand and dust into the troposphere - the most "restless" part of the atmosphere, where strong winds constantly blow at different heights (the upper border of the troposphere in the equatorial zone is at altitudes of about 15-18 km, and at mid-latitudes - 8 –11 km). They move colossal masses of sand across the Earth, which can flow under the influence of the wind like water. Meeting small obstacles in its path, the sand forms majestic hills called dunes and dunes. They have a wide variety of shapes and heights. In the Sahara Desert, dunes are known, the height of which reaches 200-300 m. These giant waves of sand actually move several hundred meters a year, slowly but steadily advancing on the oases, filling up palm groves, wells, and settlements.

In Russia, the northern border of the distribution of dust storms passes through Saratov, Ufa, Orenburg and the foothills of Altai.

Vortex storms are complex eddy formations caused by cyclonic activity and spreading over large areas.

Streaming storms Are local phenomena of small distribution. They are unique, sharply separated and inferior in importance to vortex storms. Vortex storms subdivided into dusty, dustless, snow and squall (or squalls). Dust storms are characterized by the fact that the air flow of such storms is saturated with dust and sand (usually at an altitude of up to several hundred meters, sometimes in large dust storms - up to 2 km). In dust-free storms, due to the absence of dust, the air remains clean. Depending on the path of its movement, dust-free storms can turn into dust storms (when the air flow moves, for example, over desert areas). In winter, eddy storms often turn into snowstorms. In Russia, such storms are called blizzards, blizzards, blizzards.

The features of squall storms are fast, almost sudden, formation, extremely short activity (several minutes), a quick end, and often a significant destructive force. For example, within 10 minutes the wind speed can increase from 3 m / s to 31 m / s.

Streaming storms are subdivided into stock and jet. During katabatic storms, the air flow moves along the slope from top to bottom. Jet storms are characterized by the fact that the air flow moves horizontally or even up the slope. Stock storms are formed when air flows from the tops and ridges of mountains down into the valley or to the seashore. Often, in a given locality characteristic of them, they have their own local names (for example, Novorossiysk pine forest, Balkhash pine forest, Sarma, Garmsil). Jet storms characteristic of natural corridors, passages between mountain chains connecting various valleys. They also often have their own local names (for example, Nord, Ulan, Santash, Ibe, Ursatyevsky wind).

The transparency of the atmosphere largely depends on the percentage of aerosols in it (the concept of "aerosol" in this case includes dust, smoke, fog). An increase in the content of aerosols in the atmosphere reduces the amount of solar energy coming to the Earth's surface. As a result, cooling of the Earth's surface is possible. And this will cause a decrease in the average planetary temperature and the possibility, ultimately, of the beginning of a new ice age.

Decreased atmospheric transparency contributes to interference with aviation, shipping and other modes of transport, and is often the cause of major transport emergencies. Air pollution with dust has a harmful effect on living organisms and flora, accelerates the destruction of metal structures, buildings, structures and has a number of other negative consequences.

Dust contains solid aerosols, which are formed in the process of weathering of the earth's rock, forest fires, volcanic eruptions and other natural phenomena; solid aerosols of industrial emissions and space dust, as well as particles in the atmosphere formed during crushing during explosions.

By origin, dust is divided into space, marine, volcanic, ash and industrial. The constant amount of cosmic dust is less than 1% of the total dust in the atmosphere. The seas can participate in the formation of dust of marine origin only through the deposition of salts. This appears in a noticeable form occasionally and at a short distance from the coast. Dust of volcanic origin Is one of the most significant air pollutants. Fly ash formed as a result of weathering of the earth's rock, as well as during dust storms.

Industrial dust- one of the main components of air. Its content in the air is determined by the development of industry and transport and has a pronounced upward trend. Already now in many cities of the world a dangerous situation has been created due to the dustiness of the atmosphere with industrial emissions.

Kuruma

Kuruma outwardly, they are placers of coarse detrital material in the form of stone mantles and streams on mountain slopes with a steepness less than the angle of repose of coarse detrital material (from 3 to 35–40 °). There are a lot of morphological varieties of kurums, which is associated with the nature of their formation. Their common feature is the nature of the laying of coarse-grained material - a fairly uniform size of the fragments. In addition, in most cases, the debris from the surface is either covered with moss or lichen, or simply have a black "tan crust". This indicates that the surface layer of debris is not prone to displacement in the form of rolling. Hence, apparently, their name - "kurums", which from the ancient Türkic means either "sheep herd" or an accumulation of stones similar in appearance to a herd of sheep. In the literature, there are many synonyms for this term: stone stream, stone river, stone sea, etc.

The most important feature of the kurums is that their coarse-detrital cover undergoes slow movements down the slope. The signs indicating the mobility of the curums are: the roll-like character of the frontal part with the steepness of the ledge, which is close to or equal to the angle of repose of the coarse-detrital material; the presence of embankments oriented both along the dip and along the strike of the slope; the drip character of the curum body as a whole.

The activity of kurums is evidenced by:

- rupture of lichen and moss cover;

- a large number of vertically oriented boulders and the presence of linear zones with long axes oriented along the slope;

- large duty cycle of the section, the presence of buried sod and tree remains in the section;

- deformation of trees located in the zone of contact with kurums;

- plumes of fine earth at the base of the slopes, carried out from the kurum cover by subsurface runoff, etc.

In Russia, very large areas of kurums occupy the Urals, Eastern Siberia, Transbaikalia, and the Far East. Kurum formation is determined by climate, lithological features of rocks and the nature of the weathering crust, dissection of the relief and tectonic features of the territory.

The formation of kurums occurs in harsh climatic conditions, the main of which is the amplitude of fluctuations in air temperatures, which contributes to the weathering of rocks. The second condition is the presence on the slopes of rocks that are resistant to disintegration, but
fissured, giving, when weathering, large parts (lumps, crushed stone). The third condition is the abundance of atmospheric precipitation, which forms a powerful surface runoff, washing out the coarse-clastic cover.

The most active kurum formation occurs in the presence of permafrost. Their appearance is sometimes noted in conditions of deep seasonal freezing. The thickness of the curums depends on the depth of the seasonally thawed layer. On the Wrangel Islands, Novaya Zemlya, Severnaya Zemlya and in some other regions of the Arctic, the kurums have a "film" character of a coarse detrital cover (30–40 cm). In northeastern Russia and the north of the Central Siberian Plateau, their thickness increases to 1 m and more, tending to increase to the south to 2–2.5 m in South Yakutia and Transbaikalia. In the same geological structures, the age of the kurums depends on their latitudinal position. So, in the Northern and Polar Urals, modern kurum formation is taking place, and in the Southern Urals most of the kurums are "dead", relict.

In continental areas, the most favorable conditions for kurum formation are found in areas with high humidity. In a temperate climate, intensive kurum formation occurs within the mountain belt of mountains and the forest belt. Each climatic zone is characterized by its own ranges of heights, in which the formation of kurum is observed. In the Arctic zone, kurums are developed in the range of heights from 50–160 m on Franz Josef Land, up to 400–450 m on Novaya Zemlya, and up to 700–1500 m in the north of the Central Siberian Plateau. In the Subarctic, the range of heights is 1000–1200 m in the Polar and Northern Urals, in the Khibiny. In the continental temperate zone, kurums are found at an altitude of 400–500 m in the southern part of the Central Siberian Plateau, 1100–1200 m in the west and 1200–1300 m in the east of the Aldan Upland, 1800–2000 m in the southwestern Transbaikalia. In the continental sector of the Subboreal zone, kurums are found at altitudes of 600–2000 m in the Kuznetsk Alatau, 1600–3500 m in Tuva. As a result of studying the curums of Northern Transbaikalia, it was found that only in this region there are about 20 morphogenetic varieties of them (Table 2.49). Curums differ from each other in shape in plan, in the structure of the curum body in section, and in the structure of the coarse-detrital cover, which is associated with different conditions for the formation of curums.

According to the sources of education, two large classes of kurums are distinguished. The first class unites kurums, into which coarse-grained material comes from their bed due to its destruction by weathering, removal of fine earth, bulging of debris and other processes. These are kurums with the so-called internal nutrition. The second class includes kurums, the debris of which comes from outside due to the action of gravitational processes (rock falls, talus, etc.). Kurums of the second type are spatially localized in the lower parts or at the foot of actively developing slopes and are small in size.

Internal feeding kurums are divided into two subgroups: developing on loose sediments and on rocks. Kurums on slopes composed of loose sediments are formed as a result of cryogenic bulging of coarse detrital material and suffosion removal of fine earth from it. They are confined to moraines, deluvial-solifluction accumulations, deposits of ancient alluvial fans and other genetic varieties, consisting of blocks, crushed stone with a fine-grained aggregate. Often such kurums are laid along shallow erosional hollows and other superimposed exogenous forms.

The most widespread, especially in the alpine belt of the mountains, are kurums with internal nutrition, developing on rocks of various origins and composition, resistant to weathering and giving large detachments (blocks, crushed stone) when destroyed. The geological and geomorphological setting in which they are formed has a significant effect on the structure of all types of curums (Table 2.50). On a relatively homogeneous composition and structure of the root substrate and slopes with the same slope, the kurum-forming processes manifest themselves relatively uniformly over the area. In this case, a similar section appears on the curum slope along its strike. The structure and cryogenic features of the kurum cover change mainly downslope. If the root substrate is heterogeneous in composition and structure, then the cover is formed unevenly over its entire area as a result of the selective manifestation of exogenous processes. In this case, kurums of various shapes (linear, reticulate, isometric) are formed, belonging to the group of selective weathering of rocks.

The most important feature of kurums, which predetermines their danger, is their cross-sectional structure. It is the structure that determines their geodynamic and engineering-geological features, that is, the danger of curums when interacting with various engineering objects. The structure of the curums in the sections is diverse. If we take into account the size of the fragments, the nature of their processing and sorting in a vertical section, the presence of chalice ice or fine earth, its relationship with the part of the section that is in permafrost, and other hazards, then there are no similarly constructed barrows. However, when generalizing the details of the structure, 13 main types of sections were identified, which correspond to certain conditions of kurum formation and reflect the specifics of the processes occurring in one or another part of the coarse clastic material.

First group unites the sections, in the structure of which there is a layer with alpine ice. The part of the curum body that has such a structure is called subfacies with alpine ice. This subfacies is an indicator that the curum is in a mature stage of its development, since the formation of the ice-soil layer occurs due to a decrease in the depth of seasonal thawing as a result of the destruction of rocks and an increase in their moisture content (ice content). The movement of the coarse-detrital material of the subfacies is carried out due to thermogenic and cryogenic desertion, plastic deformations of the ice-ground base, as well as slipping of debris along it.

100 great records of the elements [with illustrations] Nepomniachtchi Nikolai Nikolaevich

The worst dust storm

The worst dust storm

The warriors of the Persian king Cambyses moved forward with difficulty. Ridges of sand lay as far as the eye could see. Having conquered in 525 BC. NS. Egypt, the lord of the Persians, did not get along with his priests. The servants of the temple of the god Amun predicted a quick death to him, and Cambyses decided to punish them. An army of fifty thousand was sent on a campaign. Her path ran through the Libyan desert. Seven days later, the Persians reached the large oasis of Kharga, and then ... disappeared without a trace.

Talking about this, the ancient Greek historian Herodotus adds: "Apparently, the warriors of Cambyses were killed by the strongest sandstorm."

There are many descriptions of sandstorms in deserts. Nowadays, when the desert is crossed by highways, and airways run over them in all directions, travelers are no longer threatened with death on the great caravan routes. But before ...

An hour or half an hour before a merciless storm rises, the bright sun dims, clouded over with a cloudy veil. A small dark cloud appears on the horizon. It expands rapidly, blocking out the blue sky. Here came the first furious gust of hot, prickly wind. And in a minute the day fades. Clouds of burning sand mercilessly flog all living things, block the midday sun. In the howl and whistle of the wind, all other sounds disappear. “Both people and animals were suffocating. There was not enough air itself, which seemed to rise upward and flew away along with the reddish, brown haze that had already completely covered the horizon. My heart was pounding terribly, my head ached mercilessly, my mouth and throat were dry, and it seemed to me that another hour - and death by strangulation by sand is inevitable. ” So the Russian traveler of the XIX century A.V. Eliseev describes a storm in the deserts of North Africa.

Sandstorms - samums - have been fanned by gloomy fame for a long time. No wonder they bear this name: samum means “poisonous”, “poisoned”. Samums really destroyed whole caravans. So, in 1805, the samum, according to the testimony of many authors, covered two thousand people and one thousand eight hundred camels with sand. And, quite possibly, the same storm once destroyed the army of Cambyses.

It happens that the testimonies of people who have endured the test of the elements sin with exaggerations. However, there is no doubt that samum is very dangerous.

Fine sandy dust, which is raised by a strong wind, penetrates the ears, eyes, nasopharynx, and lungs. Dry air currents inflame the skin and cause excruciating thirst. Saving lives, people lie on the ground and tightly cover their heads with clothes. It happens that from suffocation and high temperature, often reaching fifty degrees, they lose consciousness. Here is an excerpt from the travel notes of the Hungarian explorer of Central Asia A. Vamberi: “In the morning we stopped at the station, which bears the cute name of Adamkirilgan (place of death of people), and we just had to look around to see that this name was given for a reason. Imagine a sea of ​​sand going in all directions, as far as the eye can see, pitted by the winds and representing, on the one hand, a series of high hills lying in ridges like waves, and on the other, like the surface of a lake, even and covered with wrinkles and ripples. Not a single bird in the air, not a single animal on the ground, not even a worm or grasshopper. There were no signs of life, except for the bones, whitened in the sun, collected by every passer-by and laid on the path to make it easier to walk ... Despite the oppressive heat, we were forced to walk day and night, for five or six hours in a row. We had to hurry: the sooner we get out of the sands, the less danger we get under the tebad (feverish wind), which can cover us with sand if it gets caught on the dunes ... When we approached the hills, the caravan-bashi and guides pointed out to us an approaching cloud of dust warning you to dismount. Our poor camels, more experienced than ourselves, already felt the approach of the Tabbad, desperately roared and fell to their knees, stretching their heads along the ground, and tried to bury them in the sand. We hid behind them, as if behind cover. The wind blew in with a dull noise and soon covered us with a layer of sand. The first grains of sand that touched my skin gave the impression of a fiery rain ... "

This unpleasant meeting took place between Bukhara and Khiva. Many desert storms owe their birth to passing cyclones, which also affect deserts. There is another reason: in deserts during the hot season, atmospheric pressure decreases. Hot sands heat up the air at the surface of the earth. As a result, it rises up, and currents of colder, dense air rush to its place at very high speeds. Small local cyclones are formed, giving rise to sandstorms.

Very peculiar air currents, reaching great strength, are observed in the Pamir mountains. The reason for them is the extremely sharp difference between the temperature of the earth's surface, which is strongly heated by the bright mountain sun, and the temperature of the upper, very cold layers of the air. Winds here reach special intensity in the middle of the day, and often turn into hurricanes, raising sandstorms. And in the evening they usually subside. In some areas of the Pamirs, the winds are so strong that caravans sometimes die there even now. One of the valleys here is called the Valley of Death; it is littered with the bones of dead animals ...

The same winds often occur in the Balkhan corridor in Turkmenistan. Located between the Kopetdag ridge and the Big Balkhan mountains, this corridor stretches towards the Caspian Sea. In the spring, when the atmospheric pressure over the desert decreases, masses of still unheated heavy air rush here from the Caspian Sea. Bursting into the Balkhan corridor, squeezed by mountains, the air flow acquires the speed of a storm. In autumn, the opposite picture is observed here: the waters of the Caspian Sea keep the heat accumulated in summer for a long time, and streams of air rush to it from the desert, where the sands have long cooled down.

Such storms are familiar to our Far East as well: “… A sandstorm is ruthlessly and inexorably approaching from the vastness of Mongolia,” wrote the Khabarovsk geographer G. Permyakov. - Brown haze is covering the sky thicker and thicker. The sun turns crimson red. There is an oppressive, warm silence in the air. It's getting harder and harder to breathe, lips dry. It gets dark quickly, it seems that the bloody sun is fading. Warm dust mixed with sand rushes from the west ... Sandy hurricane in the city. He breaks trees and poles like matches, tears off the roofs of houses and sheds with a clang. All in captivity of all-pervading sand dust, warm drying wind. Trams stopped. Cars disappeared. Soon, the city seems to be falling into deep night ... Sirens howl sadly, warning: “Danger! Stop the movement! .. "

Samum is born in Xinjiang, on the huge Mongolian rocky plateau. The blizzard dust is so light that a strong wind raises it to a height of five to seven kilometers and carries it through Dzungaria, the Mongolian plateau, northeast and north of China to the ocean.

Over the Korean Peninsula and the Soviet Far East, the samum is already noticeably weakening, dropping its brown dusty wings. If the African-Arabian samum usually lasts 15-20 minutes and flies in a monstrous flurry forty times a year, then the Mongolian howls sometimes for several days and in the east of our country rarely happens more than two or three times a year. Its weakened waves reach Khabarovsk, Ussuriisk, Vladivostok, Komsomolsk and even the Sea of ​​Japan. Then the bright Khabarovsk sky turns yellow, as if it was covered with a canary veil. A smoky red sun shines through the haze. A light ocher bloom settles on the ground ... The dust storm leaves majestically and gradually. First, the palate of burnt chocolate is made coffee, then ashy; then it turns gray, and the dark disc of the sun is shown through the muddy curtain of running clouds. The hours go by, the samum dies down. The sun turns burgundy, then red, dark orange and finally takes on all the splendor of its dazzling brilliance. It's getting chilly. A dirty rain begins ... Sand whirlwinds are very dangerous in the deserts of Asia and Africa. They sometimes reach enormous sizes. Hot sand heats the air up to 50 degrees or more. The air rushes upward with force. If, in this case, the neighboring sections for any reason turn out to be less heated, then vortices are formed here. As it spirals upwards, the vortex carries away masses of sand. A rotating sand pillar forms above the ground. Sweeping away everything, he rushes forward, increasing in size. It happens that one such vortex is followed by several others. For many hours they circle the desert, collide, crumble, are born again. "

The formidable dust whirlwinds are also familiar to the North American arid steppes. Here is how Mine Reed described them in the novel “The Headless Horseman”: “From the north side over the prairie there suddenly appeared several completely black columns - there were about ten of them ... bending and bending towards each other, as if in the fantastic figures of some strange dance. Imagine the legendary titans who came to life on the prairie of Texas and danced in a fierce bacchanalia. "

Dust storms with tornadoes often occur in the deserts of Africa, Central and Central Asia. The most famous and detailed dust tornado was the 1901 red dust storm.

It began in the north of the Sahara on March 9 and by the morning of the next day spread to the entire coast of Tunisia and Tripolitania. The air, filled with reddish dust, was impenetrable; the sun was not visible, darkness fell. Panic broke out among the population. By one in the afternoon, the storm was at its maximum, and everything was covered with a layer of dark yellow and pink dust.

While the main cloud was moving over Tunisia, its borders had already crossed the Mediterranean Sea and reached Sicily.

By evening, the dust storm, still at the speed of a hurricane, reached northern Italy, and at night spread to all the Eastern Alps, covering the snow and glaciers with a thick layer of red dust. In some places there was a "bloody rain", but of a lesser intensity. By the morning of March 11, the storm crossed the Alps and moved north. By midday, it spread to northern Germany and, quickly dying down, reached Denmark, the Baltic Sea and Russia. The total weight of the dust that fell during the storm in Europe is approximately 1.8 million tons.

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