What is a dust storm? Australia hit by a powerful dust storm, residents are asked to stay indoors
DUSTY (SANDY) GRIND. Transfer of dust, dry earth or sand only at the earth's surface, to a height of less than 2 m (not higher than the level of the observer's eye).[...]
Dust storms - associated with the transfer of large amounts of dust or sand raised from the earth's surface by strong winds; particles of the top layer of dried soil, not held together by vegetation. They can be caused by both natural (drought, hot winds) and anthropogenic factors (intensive plowing of land, excessive grazing, desertification, etc.). Dust storms are characteristic mainly of arid regions (dry steppes, semi-deserts, deserts). However, sometimes dust storms can also be observed in forest-steppe areas. In May 1990, a strong dust storm was observed in the forest-steppes of Southern Siberia (wind speed reached 40 m/s). Visibility decreased to several meters, power poles were overturned, powerful trees were torn out, and fires were blazing. In the Irkutsk region, 190 thousand hectares of crops were damaged and destroyed. [...]
Dust storms occur during very strong and prolonged winds. Wind speed reaches 20-30 m/s or more. Dust storms are most often observed in arid areas (dry steppes, semi-deserts, deserts). Dust storms irrevocably remove the most fertile topsoil; they are capable of dispersing up to 500 tons of soil from 1 hectare of arable land in a few hours, negatively affect all components of the natural environment, pollute the atmospheric air, water bodies, and negatively affect human health.[...]
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), blown in places not protected by vegetation and swept into others. P. b. serves as an indicator of incorrect agricultural technology and disregard for 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 susceptible to the effects of dust storms.[...]
Dust storms are most often observed in the spring, when the wind is stronger and the fields are plowed 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 out and the fields begin to be plowed up after harvesting the early spring crops. Winter dust storms are a relatively rare phenomenon.[...]
Dust storm - the transfer of dust and sand by strong and prolonged winds, blowing away the top layers of soil. A typical phenomenon in plowed steppes, as well as in semi-deserts and deserts of the USA, China and other areas.[...]
Dust storms occur mainly during the cold season. This most active and dangerous type of deflation is facilitated by strong changes in atmospheric pressure over vast territories 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 in places not protected by vegetation and blown into others. A dust storm, as a rule, is a consequence of disturbance of the soil surface by improper agricultural practices: clearing of vegetation, destruction of the structure, drying out, etc. [...]
A storm is a type of hurricane, but has a lower wind speed. The main causes of casualties during hurricanes and storms are injuries to people from flying fragments, falling trees and building elements. The immediate cause of death in many cases is asphyxia from pressure and severe injuries. Among survivors, multiple soft tissue injuries, closed or open fractures, traumatic brain injuries, and spinal injuries are observed. Wounds often contain deeply penetrated foreign bodies (soil, pieces of asphalt, glass fragments), 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 soil erosion and weathering, carry-over or backfilling of crops, and exposure of roots.[...]
Dust storms with high wind speeds and after a long dry period are a source of innumerable disasters for the entire Southeast and southern USSR. The most destructive storms in the territory under consideration were in 1892, 1928, 1960[...]
Dust storms have caused extensive damage to soil and farming in the southern Great Plains region. They became 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 conducted during this period showed that nationwide measures were needed to save soil fertility. From 25 to 75% of the topsoil was destroyed on an area of 256 million hectares.[...]
DUST STORM. The transfer of large quantities of dust or sand by strong winds is a typical phenomenon of deserts and steppes. The surface of deserts, free from vegetation and dried out, is a particularly effective source of atmospheric dust. The visibility range during P.B. is significantly reduced. In the plowed steppes, dust storms cover crops and blow away the top layers of soil, often along 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 dust source (see dust fall). P.B. 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 in the south of Ukraine.[...]
Dust storms are a formidable and dangerous manifestation of wind erosion. It occurs on vast areas of poorly protected earth surfaces in high-speed winds and causes enormous damage to the national economy and irreparable and invaluable damage to soil fertility.[...]
These dust storms interrupted normal life in cities and on farms, interrupted classes in schools, caused new types of diseases, such as “dust pneumonia”, etc., and posed an unexpected serious threat to the existence of the population. The area of arable and pasture lands subject to wind erosion in the United States in the Great Plains region exceeds 90 million hectares. This is how the consequences of the capitalist use of natural resources in this country have dramatically affected.[...]
Dust storms are understood as a meteorological phenomenon in which strong or moderate winds lift dust, sand or small soil particles into the air from the surface of the earth, free of vegetation or with poorly developed grass cover, impairing visibility within a range of several meters to 10 km. Dust storms occur during rainless dry periods, often simultaneously with dry winds. The distribution of the number of days with dust storms largely depends on the topography. The greatest 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 Western Ciscaucasia, the number of days with dust storms decreases to 1-4 per year. In river floodplains, valleys and basins, where the soil is turfed 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 occurred over a large area in the European part of Russia - in the North Caucasus and the Volga region. In the Stavropol Territory, M. N. Zaslavsky observed areas of arable land where a layer of soil 10-20 cm thick was blown away. During the dust storm of 1969 in the European part of Russia, winter crops died over a huge area, measured in the first millions of hectares.[... ]
During local dust storms in the conditions of Kazakhstan, bо ranges from 50 to 100 m. Therefore, 5 should be 500-1000 m. [...]
The frequency of dust storms is most strongly affected by the influence of the underlying surface and the degree of protection of the territory. A necessary condition 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/sec) is enough for a dust storm to occur. Dust storms are harmful to grazing and keeping livestock in transhumance areas.[...]
By the time the dust storm occurred on April 20, early vegetable crops were sown in part of this area - carrots, onions, sorrel; the sowing is rolled with a smooth roller. Part of the unsown area was only harrowed, not rolled. A dust storm carried away a 4-5 cm layer of soil along with seeds from the compacted part of the site and threw it through a mature forest belt. The non-rolled part of the site did not erode. In the soil layer 0-5 cm before the start of the dust storm there was the following number of aggregates (in %).[...]
1.11 |
In the winter of 1969, severe dust storms were observed, caused both by meteorological conditions (eastern hurricane winds) and agrotechnical factors. In some areas of the Lower Don, a 2-5 cm layer of soil was removed from the surface of arable land with crops, and in the Stavropol Territory - a layer of soil up to 6-8 cm or more. Powerful snow-earth banks (up to 25 m wide or more, with a height of up to 2 m) were formed near forest belts. Winter crops were damaged in the Rostov region and Krasnodar region, respectively, on an area of 646 and 600 thousand hectares. However, winter crops and irrigation canals protected by forest belts, especially in the meridional direction, suffered significantly less damage than in other areas. It has been established that the main methods of protecting soils in steppe regions from dust storms are agroforestry and a high level of agrotechnical work.[...]
Frontal dust storms are shorter (up to 6-8 hours), while dust storms in storm zones can last more than a day. [...]
UV - maximum wind speed (at the height of the weather vane) during dust storms with a probability of 20% (see Table 9.3), m/s; th - field surface roughness parameter, m.[...]
The enormous significance of this phenomenon can be judged by the fact that after dust storms in 1969 on the Don and Kuban, the height of the shafts of dust deposited on mechanical barriers in the Krasnodar Territory sometimes reached 5 m. Since the formation of the barriers in question often begins with trees and bushes, it is difficult to exaggerate the positive role (especially with the development of agriculture over large areas) of forest belts.[...]
In 1957, data from V.A. Franceson and his colleagues were published on observations of dust storms on ordinary chernozems in the Kustanai region (Francesson, 1963). The authors selected a layer from 0 to 3 cm from fields of different erosion conditions and subjected them to structural analysis. As a result, it was concluded that wind resistance of the soil surface is ensured by 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 protection lumps larger than 2 mm in diameter as an indicator of wind resistance of the soil surface is not justified by any research. According to the structural analysis data available in the work, we divided the fractions into two groups - larger and smaller than 1 mm and calculated clumping indicators for fields that were and were not subject to erosion (Table 5).[...]
The atmosphere is naturally polluted during volcanic eruptions, forest fires, dust storms, etc. At the same time, solid and gaseous substances enter the atmosphere, which are classified as unstable, variable components of atmospheric air. [...]
In Chapter 1, we discussed the role in air pollution of dust emissions from industrial enterprises, thermal power plants, dust storms and other sources of tiny particulate matter, dust released into the atmosphere as a result of human activity. The contribution of technogenic atmospheric dust to changes in albedo can be twofold. On the one hand, a decrease in atmospheric transparency 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.[...]
Shelter forest strips - planting trees and shrubs in the form of a series of strips, designed to protect farmland and gardens from dry winds, dust storms, wind erosion, to improve the water regime of soils, as well as to preserve and maintain the species diversity of agrocenoses (restrains the mass reproduction of pests) etc. Forest belts play a particularly important role in protecting grain crops during dust storms in dry areas of the country. In 1994, in Russia, shelterbelts were created on an area of 7.2 thousand hectares, and pasture protective plantings were created on an area of 28.4 thousand hectares. [...]
The 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 soil collected in dust collectors during two dust storms consisted of 96.9% erosive soil fractions, with the most aggressive (less than 0.5 mm in diameter) accounting for 81.6%.[...]
The task is to place obstacles along the flow path 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 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.). Thus, in 1990, the world's emission of solid particles (dust) into the atmosphere amounted to 57 million tons. Especially a lot of technogenic dust is formed when burning hard or brown coal at thermal power plants, during the production of cement, mineral fertilizers, etc. Based on a study of the content suspended particles in the atmosphere at 100 global monitoring stations (for the period 1976-1985), it was found that the most polluted cities are Calcutta, Bombay, Shanghai, Chicago, Athens, etc. These artificial aerosols cause a number of negative phenomena in the atmosphere (photochemical smog, decrease in atmospheric transparency, 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. For example, specific requirements (and, accordingly, assessment methods) are imposed in forest-steppe and steppe zones - protection from dust storms and hot winds, soil consolidation, etc., or in the conditions of the North - maximum preservation of existing tree and shrub tracts, which are characterized by increased vulnerability, slow height, 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 soils, which leads to dust in the atmosphere. In meteorology, the phenomenon of soil particles being transported by strong winds is called a dust storm. The horizontal extent of a dust storm is from tens and hundreds of meters to several thousand kilometers, and the vertical extent is from several meters to several kilometers.[...]
Of the characteristics of the water regime, the most important are the average annual precipitation, its fluctuations, 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, the presence dry winds, dust storms and other favorable natural phenomena.[...]
Quarantine weeds spread along with the seeds of cultivated plants, which is facilitated by the movement of large volumes of seed, food and feed grain within the country and from abroad. Most often, sources of 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 Shirinsk steppes, the latter of which has a very severe climate (Fig. 1). The Shirinskaya steppe of Khakassia is characterized by unstable atmospheric moisture with fluctuations in annual precipitation from 139 to 462 mm, as well as a very uneven distribution over the seasons. Constant and fairly 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 this is 644 mm) is almost twice the annual amount of precipitation. There are 29 days in a year with 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 dust 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 ranges 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' or more .[...]
Wind speed naturally changes throughout the day, and the intensity of wind soil erosion processes changes along with it. Obviously, the longer the wind, which has a speed greater than the critical one, the greater the soil loss will be. Typically, wind speed increases during the day, reaching a maximum at noon, and decreases in the evening. However, there are often cases when the intensity of wind erosion changes slightly during the day. Thus, in the spring of 1969 in the Krasnodar Territory, the strongest dust storms continued continuously for 80-90 hours, and in February of the same year - up to 200-300 hours.[...]
The prevailing winds are southern, southwestern and northern directions (Table 1.7). The percentage of calm days 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-defined daily variation, determined primarily by the daily variation of air temperature (Table 1.9). Diurnal fluctuations are more pronounced in the warm period and less in winter and early spring. Maximum wind speed is observed in winter. The average number of days with strong wind 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 occurred in recent years due to both natural and industrial pollution. In the winter of 1968-69, massive isolation closures were observed in the southern European part of the Soviet Union. At the same time, in one power system, over the course of several days, 57 overlaps occurred only on 220 kV overhead lines with normal insulation, as a result of which the power supply to consumers along these lines was interrupted. The reason for the overlaps is contamination of the insulators with soil dust with a high salt content during a dust storm and subsequent moistening with thick fog and drizzling rain when the temperature and humidity of the atmospheric air rise. At the outdoor switchgear of a thermal power plant located in the northwestern part of the Soviet Union and operating on shale fuel, normal insulation was used. Under unfavorable meteorological conditions at this station, insulation overlaps were repeatedly observed in normal operating mode. In the winter of 1966, after a long frosty period, a sharp warming occurred, as a result of which 220 kV disconnectors assembled from support-rod insulators of the KO-400 S type occurred. The consequences of this overlap were a large undersupply of electricity and a violation of the stability of the power system. It is possible to point out a number of other overlaps that have occurred in recent years near chemical industry plants in various regions of the Soviet Union under unfavorable meteorological conditions and emission plumes hitting insulators. For example, during heavy fog and low winds from a large petrochemical plant, external insulation overlaps were observed at distances of up to 10 km from the source of pollution. Similar overlaps with emergency consequences have been repeatedly observed abroad.[...]
The earth's atmosphere is a mechanical mixture of gases, called air, with solid and liquid particles suspended in it. To quantitatively describe 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. In addition, the concept of an atmospheric phenomenon is introduced, which is understood as a physical process accompanied by a sharp (qualitative) ) 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 combination of meteorological quantities and atmospheric phenomena, is called weather. To analyze and forecast the weather, the values of meteorological quantities, as well as special weather phenomena, determined at a single point in time at a wide network of meteorological stations, are marked on geographic maps with symbols and numbers. Such maps are called weather maps. The statistical long-term weather pattern is called climate.[...]
A type of water erosion is irrigation erosion. It develops as a result of violation of watering rules in irrigated agriculture. The movement of the upper soil horizons under the influence of strong winds is called wind erosion, or deflation. When deflation occurs, the soil loses its smallest particles, which carry away chemicals that are essential for fertility. The development of wind erosion is facilitated by the destruction of vegetation in areas with insufficient atmospheric moisture, excessive grazing, and strong winds. Sandy loam and fertile carbonate chernozems are most susceptible to it. During severe storms, soil particles can be carried away over large distances from large areas. According to M. L. Iackson (1973), on the planet every year 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 of Asia, Southern Europe, Africa, South and North America, and Australia. Currently, they are becoming a national or regional disaster in many countries. Soil losses from wind erosion amount to 400 t/ha in the most catastrophic years. 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, and 60 million hectares sharply decreased their fertility. According to R. P. Beasley (1973), in the 30s in this country there were more than 3 million hectares (about 775 million acres) of heavily eroded lands, in the mid-60s 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 grassed slopes were plowed. And this immediately affected the stability of the soil against dispersal. Crop losses on such soils today amount to 50-60%. Similar phenomena occur everywhere.[...]
Since 1963, the PAU-2 aerodynamic installation began to be 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 a field or at a stationary site over an artificially created area with specified roughness parameters), an artificial air flow similar to natural wind is created; when an air flow moves over an area of the soil surface, soil material is blown out and transferred, which is also similar to the natural erosion of soil by the wind during dust storms; Part of the fine earth transported by the air flow is captured by dust collection tubes installed at different heights above the soil surface and deposited in cyclones. Based on the amount of soil material captured by PAH-2 from the surface of the site during the experiment, the erodibility of a given soil is judged (Bocharov, 1963).[...]
A typical desert aerosol consists of 75% clay minerals (35% montmorillonite and 20% each of kaolinite and illite), 10% each of calcite, and 5% each of quartz, potassium nitrate and iron compounds limonite, hematite and magnetite with an admixture of some organic substances . According to line 1a of table. 7.1, the annual production of mineral dust varies widely (0.12-2.00 Gt). The concentration decreases with height, so that mineral dust is observed mainly in the lower half of the troposphere up to altitudes of 3-5 km, and above 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 disaster influences another, and it happens that the first disaster serves as a trigger for subsequent ones. The genetic dependence of natural disasters is shown in Fig. 2.4, the arrows depict the direction of natural processes: the thicker the arrow, the more obvious this dependence is. 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 rains can affect slope sliding. Dust storms are a direct consequence of atmospheric disturbances.[...]
An admixture of clastic material is represented by feldspars, pyroxenes and quartz. Feldspar, pyroxenes and montmorillonite come from intra-oceanic sources, and in particular the latter from 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 into the ocean, presumably by high-altitude atmospheric jet streams; the contribution of aeolian material to the composition of pelagic clays is probably from 10 to 30%. A well-studied supplier of clayey matter to the deep-sea basins of the Atlantic is the Sahara Desert - material from African dust storms can be traced all the way to the Caribbean Sea. Aeolian clays of the Indian and North Pacific Oceans were probably formed due to the removal of dust from the Asian mainland; The source of aeolian material in the South Pacific is Australia.[...]
Another factor that disturbs 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 speeds up this process by 100-1000 times compared to natural phenomena. 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 biogenic elements (P, K, 14, Ca, Mg) along with water and soil in quantities much greater than those introduced with fertilizers. The soil structure is destroyed, and its productivity decreases 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 predominates in areas of intense rain and when sprinklers are used in areas of slopes of field surfaces and saddles. Wind erosion is typical for areas with elevated temperatures, insufficient moisture combined with strong winds. Thus, dust storms carry away up to 20 cm of soil along with crops.
Sandstorm - view from an airplane
Dust (sand) storm- an atmospheric phenomenon in the form of the transfer of large quantities 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 in horizontal visibility (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). In this case, 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 occurs during the warm season in desert and semi-desert regions. In addition to the “actual” dust storm, in some cases dust from deserts and semi-deserts can remain in the atmosphere for a long time and reach almost anywhere in the world in the form of a dusty haze.
Dust storms occur less frequently in steppe regions, very rarely in forest-steppe and even forest regions (in the last two zones, a dust storm occurs more often in the summer during severe drought). In steppe and (less often) forest-steppe regions, dust storms usually occur in early spring, after a winter with little snow and a dry autumn, but sometimes they occur even in winter, in combination with blizzards.
When a certain threshold of wind speed is exceeded (depending on the mechanical composition of the soil and its moisture), particles of dust and sand come off the surface and are transported by saltation and suspension, causing soil erosion.
Dusty (sandy) drifting snow - 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 and more ). It usually occurs when the soil surface is dry and the wind speed is 6-9 m/s or more.
Causes
With an increase in the strength of the wind flow passing over loose particles, the latter begin to vibrate and then “jump”. When these particles repeatedly strike the ground, they create fine dust that rises in suspension.
Recent research suggests that the initial saltation of sand grains by friction induces electrostatic field . The jumping particles acquire a negative charge, which releases even more particles. This process captures twice as many particles as previous theories predict.
Particles are released mainly due to dry soil and increased wind. Gust fronts can occur due to cooling air in the area of a thunderstorm with rain or a dry cold front. After the passage of a dry cold front, convective instability in the troposphere can contribute to the development of a dust storm. In desert regions, dust and sand storms are most often caused by thunderstorm downdrafts and the associated increase in wind speed. The vertical dimensions of a storm are determined by the stability of the atmosphere and the weight of the particles. In some cases, dust and sand storms may be confined to a relatively thin layer due to the temperature inversion effect.
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Ways to fight
To prevent and reduce the effects of dust storms, forest shelterbelts, snow and water retention complexes are created, and also used agrotechnical methods such as grass seeding, crop rotation and contour plowing.
Environmental consequences
Sandstorms can move entire dunes and carry enormous volumes of dust, so that the storm front can appear as a dense wall of dust up to 1.6 km high. Dust and sand storms coming from the Sahara Desert are also known as shamum, khamsin (in Egypt and Israel) and habub (in Sudan).
A large number of dust storms originate in the Sahara, especially in the Bodélé Depression and in the area where the borders of Mauritania, Mali and Algeria converge. Over the past half century (since the 1950s), Saharan dust storms have increased approximately 10-fold, causing a decrease in the thickness of the topsoil in Niger, Chad, northern Nigeria and Burkina Faso. In the 1960s, only two dust storms occurred in Mauritania; currently there are 80 storms per year.
Dust from the Sahara is carried westward across the Atlantic Ocean. The intense daytime heating of the desert creates an unstable layer in the lower troposphere, in which spread dust particles. As the air mass moves (advects) westward over the Sahara, it continues to heat up, and then, reaching the oceanic expanses, passes over a colder and more humid atmospheric layer. This temperature inversion prevents the layers from mixing and allows the dusty layer of air to cross the ocean. The amount of dust blown from the Sahara toward the Atlantic Ocean in June 2007 was five times greater than the year before, which could cool Atlantic waters and slightly reduce hurricane activity.
Economic consequences
The main damage caused by dust storms is the destruction of the fertile soil layer, which reduces its agricultural productivity. In addition, the abrasive effect damages young plants. Other possible negative consequences include: reduced visibility affecting air and road transport; reducing the amount of sunlight reaching the Earth's surface; thermal blanket effect; unfavorable impact on the respiratory system of living organisms.
Dust can also be beneficial in places where it is deposited - the jungles of Central and South America receive most of their mineral fertilizers from the Sahara, the lack of iron in the ocean is compensated, dust in Hawaii helps banana crops grow. In northern China and the western United States, ancient storm sediment soils called loess are very fertile, but are also the source of modern dust storms when the vegetation that binds the soil is disrupted.
Extraterrestrial dust storms
The extreme difference in temperature between the ice shell and the warm air at the edge of Mars's southern polar cap results in strong winds that raise huge clouds of red-brown dust. Experts believe that dust on Mars can play the same role as clouds on Earth - it absorbs sunlight and thereby heats the atmosphere.
Known dust and sand storms
Dust storm in Australia (September 2009)
- According to Herodotus, in 525 BC e. died during a sandstorm in the Sahara fifty thousandth army of the Persian king Cambyses.
- In April 1928, in the steppe and forest-steppe regions of Ukraine, the wind lifted more than 15 million tons of chernozem from an area of 1 million km². Black earth dust was transported to the west and settled over an area of 6 million km² in the Carpathian region, Romania and Poland. The height of the dust clouds reached 750 m, the thickness of the black soil layer in the affected regions of Ukraine decreased by 10-15 cm.
- A series of dust storms in the United States and Canada during the Dust Bowl period (1930-1936) forced the move hundreds thousand farmers.
- In second half day 8 February 1983 of the year strongest dusty storm, appeared on north Australian state Victoria, covered city Melbourne.
- IN periods multi-year droughts years 1954 —56 , 1976 —78 And 1987 —91 on territories Northern America arose intensive dusty storms.
- Strong dusty storm 24 February 2007 of the year, appeared on territories western Texas V area cities Amarillo, covered all northern Part state. Strong wind caused numerous damage fences, roofs And even some buildings. Also strongly Suffered international airport metropolis Dallas-Fort—Worth, V hospital contacted People With problems at breathing.
- IN June 2007 of the year big dusty storm happened V Karachi And on territories provinces Sindh And Balochistan, subsequent behind her strong rains brought To of death almost 200 Human .
- 26 May 2008 of the year sandy storm V Mongolia brought To of death 46 Human.
- 23 September 2009 of the year dusty storm V Sydney brought To interruptions V movement transport And forced hundreds Human stay Houses. Over 200 Human contacted behind medical with help from—behind problems With breathing.
- 5 July 2011 of the year huge sandy storm covered
Dust (sand) storm - in the form of the transfer of large quantities of dust (soil particles, grains of sand) by wind from the earth’s surface in a layer several meters high with noticeable deterioration (usually at a level of 2 m it ranges from 1 to 9 km, but in some cases it can drop to several hundred and even up to several tens of meters). In this case, 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 take on 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 occurs in the warm season in regions. When a certain threshold of wind speed is exceeded (depending on the mechanical composition of the soil and its moisture), particles break off from the surface and are transported by and, causing soil erosion.
Dusty (sandy) drifting snow - the transfer of dust (soil particles, grains of sand) by 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 climate zones of both hemispheres of the Earth.
Desert and Deserts are the main sources of airborne dust in the area , make a smaller contribution, And . Dust storms in China carry dust to . Environmentalists believe that irresponsible management of the Earth's dry regions, such as ignoring the system, lead to and climate change at local and global levels.
Term "sandstorm", 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 refers more to the phenomenon of transport of small particles over distances of up to several thousand km, especially when storms “cover” urban areas.
High frequency of dust storms is observed 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,, , , regions, and region; on - in , , , , areas, in ; in the northern, central and eastern .
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 at points located in the forest vegetation zone - incl. V and (1-3 days during the summer).
Causes
With an increase in the strength of the wind flow passing over loose particles, the latter begin to vibrate and then “jump”. When these particles repeatedly strike the ground, they create fine dust that rises in suspension.
A recent study suggests that the initial grains of sand through friction induces . The bouncing particles acquire a negative charge, which releases even more particles. This process captures twice as many particles as previous theories predict.Particles are released mainly due to and wind. Gust fronts may occur as air cools after a strong with rain or may be dry . After the passage of a dry cold front instability could create a dust storm. In desert areas, dust and sand storms most often occur as a result of thunderstorm outlets and increased wind speeds. The vertical dimensions of a storm are determined by the stability of the atmosphere and the weight of the particles. In some cases, dust and sand storms may be confined to a relatively thin layer due to the temperature inversion effect. In other cases, dust can rise to a height of 6100 m.
Ways to fight
To prevent and reduce the effects of dust storms, forest shelterbelts, snow and water retention complexes are created, and agrotechnical methods are used, such as grass sowing, and contour plowing.
Environmental consequences
Sandstorms can move entire and carry enormous volumes of dust, so that the storm front can appear as a dense 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 basin and in the area of convergence of boundaries, And . Over the past half century (since the 1950s), Saharan dust storms have increased approximately 10-fold, causing a decrease in the thickness of the topsoil in, Chad, northern and . In the 1960s, Mauritania experienced only two dust storms, but currently experiences 80 storms per year. Volume of dust blown from the Sahara towards the Atlantic Ocean in June five times more than a year ago, which could cool Atlantic waters and reduce activity slightly .
Economic consequences
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: decreased , 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 areas of deposition - And receives most of its mineral fertilizers from the Sahara, replenishes the lack of iron in the ocean, dust on helps to grow cultures. In northern China and the western United States, soils with sediment from ancient storms, called , are very fertile, but are also the source of modern dust storms when the vegetation that binds the soil is disrupted.
Extraterrestrial dust storms
The strong difference in temperature between the ice shell and warm air at the edge of Mars's southern polar cap leads to the occurrence of strong winds that raise huge clouds of red-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.
| Origin and types of storms. Their consequences
Basics of life safety
7th grade
Lessons 11 - 13
Hurricanes, storms, tornadoes
Lesson 12
Origin and types of storms. Their consequences
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Hurricane-force winds often lead to storms.
Storm - very strong (with a speed of over 20 m/s) and prolonged wind. Storms are characterized by lower wind speeds than hurricanes, and their duration of action ranges from several hours to several days.
Depending on the time of year, the place of their formation and the entrainment of particles of various compositions into the air, dusty, dustless, snow and squall storms are distinguished.
Dust (sand) storms are accompanied by the transfer of large amounts of soil and sand particles. They occur in desert, semi-desert and steppe areas, where there is soil not covered with grass. When there is a strong wind, a large amount of dust and small particles of earth rise into the air. Dust storms can transport millions of tons of dust over hundreds and even thousands of kilometers and cover an area of several hundred thousand square kilometers with it. The destructive impact of such a storm occurs additionally due to the impact of earth particles moving at high speed. Such storms usually occur in the summer, during dry winds, sometimes in the spring and during snowless winters. In the steppe zone they often arise due to irrational plowing of land. In Russia, the northern border of the distribution of dust storms passes through Saratov, Samara, Ufa, Orenburg and the foothills of Altai.
For dust-free storms characterized by the absence of dust entrainment into the air and a relatively smaller scale of destruction and damage. However, as they move, they can turn into dust or snow storms.
For snow storms Significant wind speeds are also characteristic, which contributes to the movement of huge masses of snow through the air in winter. The duration of such storms ranges from several hours to several days. They have a relatively narrow range (from several kilometers to several tens of kilometers). In Russia, snow storms of great force occur on the plains of its European part and in the steppe part of Siberia.
For squalls Characterized by an almost sudden onset, an equally rapid ending, short duration and enormous destructive power. In Russia, these storms are widespread throughout its European part (in marine areas, where they are called squalls, and on land).
Storms are classified depending on the color and composition of the particles involved in the movement, as well as on wind speed (Scheme 13).
Dust storms- these are storms that occur in deserts, semi-deserts and plowed steppes, accompanied by the transfer of large quantities of soil and sand particles. They are capable of transporting millions of tons of dust over hundreds and even thousands of kilometers, covering an area of several hundred thousand square kilometers. Such storms occur mainly in the summer, during dry winds, sometimes in the spring and during snowless winters. In the steppe zone they usually occur due to irrational plowing of land. In Russia, the northern border of the distribution of dust storms passes through Saratov, Samara, Ufa, Orenburg and the foothills of Altai.
Dustless storms- these are storms characterized by the absence of dust entrainment into the air and a relatively smaller scale of destruction and damage. However, with further movement they can turn into a dust or snow storm, depending on the composition and condition of the earth's surface and the presence of snow cover.
Ice storms may occur at the beginning and end of snow storms. They consist of a mixture of rain, snow (grass) and hail.
Grits are small melted grains of ice. These ice grains form in two ways: when raindrops pass through a layer of air with a temperature below freezing, or when snowflakes fall through a layer of air with a temperature above freezing. Unlike hail, which can fall at any time of the year, pellets appear only in winter.
Although graupel is a nuisance, it rarely causes the widespread destruction that hail does. Thus, human and material losses in this section relate entirely to the effects of hailstones.
Hail is precipitation in the form of ice balls and a mixture of ice and snow. Hail typically occurs during the passage of a cold front or during a thunderstorm.
The largest hailstones are simple structures formed when the surface of snowballs melts and freezes again, or becomes covered with water droplets that then freeze. Thus, hailstones have a hard outer shell and a soft core.
Large hailstones with a diameter of 1.2 to 12.5 centimeters are more complex structures.
There are various theories of their formation. They usually consist of alternating layers of hard and soft ice. One theory is that they form in clouds when ultra-cold droplets freeze on dust particles or snowflakes. These tiny hailstones are then repeatedly carried up and down by the wind. Each time they pass through an area with a temperature above freezing, they absorb moisture, and as they rise upward into an area with a temperature below freezing, they either freeze or build up a new layer of snow. Hailstones continually grow until they reach a weight that the wind cannot support, and then they fall to the ground.
Another theory suggests that hailstones pass through various air pockets, building up layers in zones of air containing varying amounts of moisture.
Whatever the method of formation, hail causes amazing destruction and loss of life.
Timeline of the worst ice storms
Snow in its softest form is what children and romantics expect from the first day of November and from the moment the thermometer drops below zero. Snow has the ability to soften the sharp edges of urban landscapes and provides opportunities for boys to play with their imagination.
But in a less mild form, bursting into our lives in the form of a snowstorm, it can become a killer.
Snow itself is precipitation formed by the transition of water vapor into solid crystals at a temperature below freezing. Condensation usually occurs around dust particles in the same way as when raindrops form. Only snowflakes come out in the form of hexagonal plates, among which not a single pair is identical. The differences in size and shape are the result of multiple crystals coming together as snowflakes pass through warmer layers of air.
On average, 250 millimeters of snow equals 25 millimeters of rain, and the factors that determine rainfall are about the same as snowfall.
Blizzards, then, are winter storms characterized by low temperatures, strong winds and snowfall. Whereas a hurricane has tropical temperatures, strong winds and rain. The US Weather Bureau published a collection of definitions in 1958, which indicates the parameters of natural phenomena. So, for northern latitudes, snowfall becomes a blizzard when the wind speed reaches 56 kilometers per hour and the temperature drops below minus seven degrees. Blizzards may extend as far south as Texas and as far east as Maine.
Timeline of the most severe snow storms
Squalls (Squalls)– horizontal vortices under the edge of an advancing band of powerful cumulonimbus clouds. The width of the squall corresponds to the width of the atmospheric front and reaches hundreds of kilometers. The speed of air movement in the vortex adds up to the speed of the front and in some places reaches hurricane speed (up to 60–80 m/s). This is how squalls or storms are formed. Their width is a few kilometers, rarely up to 50 km, the path length is 20–200 km, rarely up to 700 km, the duration at each point of the path is from several to 30 minutes. They are accompanied by heavy downpours and thunderstorms. Squalls and local squall storms are typical for all areas covered by cyclonic activity. Their frequency and seasonality depend on certain characteristics of the colliding air masses and vary from place to place. For the European part of Russia, statistics for the Nizhny Novgorod region are representative: the season of squalls is April - September, maximum frequency (more than 1 day out of 5) - from May 26 to June 10; number of days per season with squalls faster than 15 m/s – 18.1; 20 m/s – 9.3; 25 m/s – 2.4; faster than 30 m/s – 0.8 days.
The destructive impact of squalls is determined by wind speed, as well as thunderstorms and flash floods. In the European part of Russia, one squall can damage crops over an area of up to several tens of thousands of hectares, dozens of houses and outbuildings with one-time damage of up to several million rubles.
Squalls are similar to flow or jet storms. They are associated with atmospheric fronts, but do not have a vertical convective component, as with squalls, and are created by air flows in valleys and along the edges of hills. Storms of this type reach speeds of 40–50 m/s and last 12–24 hours, up to a maximum of a week. These include: Novaya Zemlya, Novorossiysk, Adriatic bora, Orosi in Japan, Sarma and Barguzin on Lake Baikal, Mistral in the Rhone Valley (France), Tramontana in Italy, Chinook from the Rocky Mountains in Canada, Khazri along the eastern edge of the Caucasus near the Caspian Sea and others local storms.
The hazards they cause vary depending on the time of year and local conditions. Let's name some examples: Novorossiysk forest in winter - storm in Tsemes Bay, splashing and icing (ice thickness - up to 4 m) of port buildings; Balkhash forest with ridge. Chingiz - snowstorm in winter, dust storm in summer; hairdryer in the Alps in winter and spring - extreme snowmelt, floods, mudflows, landslides, and if the air temperature is not high enough - severe snowstorms, etc.
Consequences of storms are damage and destruction of buildings, power and communication lines, the formation of drifts and blockages on roads, destruction of agricultural crops, damage and loss of ships. These natural disasters kill animals, injure people, and kill people. People in hurricane and tornado zones are most often struck by flying objects and collapsing structures. A secondary consequence of hurricanes are fires that occur due to accidents on gas communications, power lines, and sometimes as a result of lightning strikes.
Storms lead to much less destructive consequences than hurricanes. However, they, accompanied by the transfer of sand, dust or snow, cause significant damage to agriculture, transport and other sectors of the economy.
Dust storms cover fields, populated areas and roads with a layer of dust (sometimes reaching several tens of centimeters) over areas of hundreds of thousands of square kilometers. In such conditions, the harvest is significantly reduced or completely lost and large amounts of effort and money are required to clean up settlements, roads and restore agricultural land.
Blizzards in our country they often achieve great strength over vast areas. They lead to the cessation of traffic in cities and rural areas, the death of farm animals and even people.
Thus, storms, being dangerous in themselves, in combination with the phenomena accompanying them create a difficult situation, bringing destruction and casualties.
Measures to protect the population from storms:
Timely forecast and warning of the population;
- reducing the impact of secondary damage factors (fires, dam breaks, accidents);
- increasing the stability of communication lines and power supply networks;
- preparation of shelters, basements and other buried structures for sheltering people;
- shelter in durable structures and places that provide protection for farm animals; provision of water and feed for them.
Dust storms are caused by strong winds from the earth's surface and transport by air currents of mineral dust, sand, salts and other particles, mostly less than one millimeter in size.
On the territory of Kazakhstan, dust storms are most often observed in April-May and August-September. Relatively rarely, they can develop in the winter months, if the surface of the earth is not covered with snow.
An increased frequency of strong dust storms was noted in the west of Kazakhstan and the eastern coast of the Caspian Sea, along the valley of the Syr Darya River and in the Aral Sea region, the Torgai depression, the sandy deserts of Kyzylkum, Moinkum and the Balkhash region, the flat areas of central and northern Kazakhstan, and in the valley of the Irtysh River. The number of these storms in these areas can reach from 5-6 to several dozen per year.
Storms cause a whole range of adverse effects on the human body, the surrounding nature and mechanisms.
In the Irtysh region on May 19, 1960, a dust storm lasted 12 hours, as a result of which a desert covered with uprooted wheat spread out in place of friendly shoots. During the storm, the air was so saturated with dust that it was impossible to see a person 3-4 m away, and lights were turned on in the houses during the day.
From earlier information about catastrophic dust storms in Kazakhstan, the following can be cited: “In November 1910, the storm began in the evening. On the first night, the wind reached enormous strength and then raged without a break for three days. All this time, people did not leave their tents, because and during the day it was dark. Along with the mass of dust, sand and snow, even small stones were carried into the steppe by the wind, where most of the livestock died. In the area of Mangyshlak alone, 0.5 million sheep and goats died. . horses and 0.03 million camels."
Precautionary measures
If you are in a populated area, when a dust storm approaches, you should take shelter indoors, tightly closing windows and doors. Pets must be confined to their designated pens or areas.
If you are away from settlements on pastures in the sand, you need to shelter the cattle in a depression between fixed ridges of sand. If there are thickets of saxaul or tall bushes nearby, it is better to place the livestock there until the storm is over.
If a storm catches you on the way far from populated areas, then if visibility deteriorates to the point where you can lose your bearings and get lost, you must stop moving. It can be resumed only after the end of the storm or when the visibility range increases to a kilometer or more. If the path is lost, then it is necessary to stay in place and organize distress signals after the storm - light clearly visible fires from highly smoking materials.
If you are in a car, then if visibility is lost, you need to pull over to the side of the road, turn off the engine, and tightly close the doors and windows of the cabin. Cover the engine air filter with cloth. Ground the car body. After the storm is over, clean the engine of sand and dust, remove matter from the air filter, start the engine and start driving.
If during a dust storm you find yourself in the open air outside closed rooms and car interiors, you need to fasten your clothes tightly, put on a hat, and protect your eyes from dust and sand particles with special glasses. If you don’t have them, you can use regular glasses, covering them on the side with your hands to minimize the possibility of dust getting into your eyes. It is necessary to find some shelter from the wind: thickets of bushes, saxaul, and use uneven terrain. If you have any kind of cape, you can use it as protection from dust, cold wind and hypothermia.
During dust storms that occur at elevated air temperatures (more than 35°C), it is necessary to take measures against overheating of the body. To do this, you need to have a supply of fresh water at the rate of 8 liters per person per day. Periodically during a storm, drink a few sips of water, ensuring the body sweats. At these air temperatures, it is advisable to limit mobility.
To limit the entry of dust into the respiratory system, it is advisable to breathe during a storm through some kind of mask made of several layers of gauze, cloth or a handkerchief. If possible, use a personal protective respirator such as “Petal” or R-2.
In the presence of atmospheric electricity and lightning discharges during storms, it is necessary to ground premises, cars, antennas of radio receiving and transmitting devices, and television equipment. Operating personnel must ensure that power and communication lines are protected from electrical discharges.
You cannot seek shelter from storms near power lines or isolated trees.