How do dust storms occur?

Dust storms are a meteorological phenomenon, but associated with the state soil cover and with terrain. They are akin to snowstorms: for the occurrence of both, they need strong wind and a sufficiently dry material on the surface of the earth, capable of rising into the air and being suspended there for a long time. But if for the appearance of blizzards, dry, non-caked snow lying on the surface and a wind speed of 7-10 m / s or more is needed, then for the occurrence of dust storms, the soil must be loose, dry, devoid of grass or any significant snow cover and the wind speed was at least 15 m / s. Dust storms are most common in early spring, in March or April, after dry autumn and winter with little snow. They happen, although less often, in winter - in January or February and very rarely - in other months of the year. The most typical synoptic environment for dust storms is the southern or southwestern periphery of a stable, inactive anticyclone, which determines dry weather with strong easterly or southeasterly winds.

Depending on the structure and color of the soils blown / by the wind, black storms (on chernozems) are distinguished, characteristic of the southern and southeastern regions of the European part of Russia, Bashkiria, and the Orenburg region; brown or yellow storms (on loams and sandy loams), typical Central Asia; red storms (on red-colored soils colored with iron oxides) typical of the deserts and semi-deserts of Central Asia (as well as, outside our country, the desert areas of Iran and Afghanistan); white storms (on salt marshes), characteristic of some regions of Turkmenistan, the Volga region, Kalmykia.

Wind-carried dust can settle and accumulate in areas where the wind is weaker. In the south-west of Ukraine, in the middle reaches of the Don, between the rivers Khoprom and Medveditsa, there are places with dust deposits several meters or more thick. In snowless winters in the southeastern regions of the country, which are characterized by loose and dry soils that are easily deflated (that is, wind erosion), with very strong and stable winds, winter black storms occur, blowing out the soil along with winter crops not covered with snow. Such "black winters" were in 1892, 1949, 1951, 1960 and 1968.

TITLE: Amazing world around us. Questions about the weather. Weather related natural disasters

HEADER: Why are dust storms dangerous?

SHEADER: Why are dust storms dangerous?

ANONCE: This phenomenon, in terms of its scale and consequences, can be equated to large natural disasters

DESCRIPTION: This phenomenon in its scale and consequences can be equated to major natural disasters

KEYWORDS: weather, meteorology, question, advice, recommendation, history, fact, element, calamity, whim, winter, spring, summer, autumn, region, continent, forecast, dusty, storm, natural, calamity, cloud, fog, dust

AUTHORS: P. D. Astapenko

Why are dust storms dangerous?

In terms of its scale and consequences, this phenomenon can be equated with major natural disasters. V. V. Dokuchaev describes one of the cases of a dust storm in Ukraine in 1892 as follows: degrees of frost. Clouds of dark earthen dust filled the frosty air, covering the roads, bringing in the gardens - in some places the trees were brought to a height of 1.5 meters, - they lay down ramparts and mounds on the streets of the villages and greatly impeded movement along railways: we even had to tear off the railway stations from the drifts of black dust mixed with snow. "

During a dust storm in April 1928 in the steppe and forest-steppe regions of Ukraine, the wind raised more than 15 million tons of black soil from an area of ​​1 million km2. The black earth dust was transported to the west and settled on an area of ​​6 million km in the Carpathian region, Romania and Poland. The height of dust clouds over Ukraine reached 750 m. The thickness of the chernozem layer in the steppe regions of Ukraine after this storm decreased by 10-15 cm.

The danger of this phenomenon also lies in the terrible force of the wind and its extraordinary impetuosity. During dust storms over Central Asia, the air is sometimes saturated with dust up to a height of several kilometers. Aircraft caught in a dust storm are in danger of being destroyed in the air or upon impact on the ground; in addition, the visibility range in a dust storm can be reduced to tens of meters. There were cases when during the day with this phenomenon it became dark as at night, and even electric lighting did not help. If we add that dust storms on the ground can lead to the destruction of buildings, windbreaks, not to mention the all-pervading dust that gets into houses, soaks people's clothes, obscures their eyes, makes breathing difficult, then it becomes clear how dangerous this phenomenon is and why it is called natural disaster ...

Dust storms usually last for several hours, but in individual cases- and several days. Some dust storms originate far beyond the borders of our country - in North Africa, on the Arabian Peninsula, from where air currents bring dust clouds to us.

Huge, swirling reddish clouds of sand and dust, raised from the surface of the earth by dry, hot and fast air currents, bring death within them. So, in 1805 dust storm completely covered with sand a caravan of two thousand people and the same number of camels. The same story befell the Sahara in 525 BC. legendary army Persian ruler Cambyses II: terrible sandstorm halfway through, she stopped a military expedition, killing about fifty thousand soldiers.

A sure sign that a sandstorm is approaching is the unexpected silence when the wind stops blowing, and with it all sounds and rustles disappear. Instead, the stuffiness intensifies, and along with it, anxiety appears on a subconscious level. And after a while, a fast-growing cloud of black-purple color appears on the horizon. The wind reappears and picks up speed, raising dust and sand.

Sandstorm, or as it is also called, dust storm is atmospheric phenomenon when strong winds move a huge amount of grains of sand, soil particles or dust over long distances. The height of such a cloud can exceed a kilometer, while the visibility inside it decreases to several tens of meters.

As these particles settle, the soil becomes reddish, yellowish or grayish (depending on the composition of the particles lifted into the air). Despite the fact that dust storms appear mainly in summer, in the absence of precipitation and rapid drying of the soil, they occur in winter.

Dust storms are formed mainly in desert or semi-desert regions (the Sahara desert is especially famous for them), but sometimes due to drought it can also occur in the forest-steppe and forest regions of the planet. So, in April 2015, a sandstorm hit Khmelnitsky, a city located in western Ukraine. The hurricane lasted about five minutes, visibility did not exceed ten meters, and the wind was so strong that it almost blew people and vehicles off the bridges.

How a storm is formed

For a dust storm to arise, a dry soil surface and a wind speed of more than 10 m / s are required (for example, in the Sahara, its indicators often reach 50 m / s). Dust storms appear due to turbulence (inhomogeneity) of air flows, which, when moving along uneven surface colliding with obstacles, they form air vortexes. The faster the wind moves, the more dangerous turbulence it creates.

After the movement of air masses increases over loose soil particles, the adhesion between which is weakened due to the dryness of the soil (which is why storms of this type appear mainly in deserts), the grains of sand begin to vibrate first, then jump, and as a result of repeated impacts they turn into small dust.

Swirling air easily lifts sand or dust particles from the ground, while the temperature lower layers air masses increase greatly: over the steppes - up to 1.5 km, over deserts - up to 2.5 km. After this, air is mixed with dust particles, which tend to be distributed over the entire area of ​​the heated air.

While smaller particles fly extremely high above the earth's surface, larger particles rise to a lower distance and fall quickly (if the wind is extremely strong, dust can be carried thousands of kilometers). The strength of the wind during sandstorms is such that it is quite capable of moving the dunes, and the sand raised by it will be like a huge cloud one and a half kilometers high.

For a dust storm to form, the soil must be dry: in case of prolonged drought, exposure to strong winds, even particles of the upper layers of chernozem soil are able to rise into the air (in this case, a "black storm" is formed), and move over long distances.

So, at the end of the twenties of the last century in the forest-steppe and steppe forests of Ukraine, a dust storm that suddenly appeared raised more than 15 million tons of chernozem (while the height of the cloud was 750 m) and transferred them thousands of kilometers to the side. Some of the dust settled in the Carpathian region, Poland and Romania, as a result of which the fertile soil layer in the affected regions (about 1 million km2) decreased by 10-15 cm.

How long does the phenomenon last

Sandstorms usually last from thirty minutes to four hours. At the same time, short-term dust storms are characterized by a slight deterioration in visibility: the terrain is visible up to four, and sometimes up to 10 kilometers.

Among the short-term there are also such dust storms, during which the visibility is limited to two tens of meters.

A dust storm always appears almost unexpectedly: in good weather, a squall wind will rise, as a result of which the speed of air currents increases, picking up and lifting dust particles into the air.

True, poor visibility does not last long, even though the wind speed is increasing at this time. The approaching dust storm can be recognized by the gray fog strip curtain that appears under the cumulonimbus clouds when they are located near the horizon.

There are also long sandstorms:

• Dust storms alone are characterized by only a partial deterioration in visibility, up to four kilometers (although these dust storms are the longest in time, since they can last for several days).
• For others, visibility is limited to several meters at the initial stage of development, after which it clears up to one kilometer. But these sandstorms last no more than four hours.

Storms of the Sahara

Many sandstorms originate in the world's largest desert, the Sahara, where Mauritania, Mali and Algeria border each other. Over the past half century, the number of sandstorms in the Sahara has increased tenfold (only through Mauritania, about eighty storms sweep through the year).

There is so much uplifted sand in the Sahara that huge amounts of sand particles are transported across the Atlantic Ocean. This situation is possible due to the fact that when dust and sand move over the desert, they continue to heat up with the air, after which, once over the ocean, they pass under a colder and wetter air stream. The difference in temperature between layers of air causes them not to mix with each other, allowing dusty warm air to cross the ocean.

Despite the fact that sandstorms cause many negative consequences (destroy the fertile soil layer, adversely affect respiratory system living organisms), dust lifted into the air is also beneficial. For example, dust storms from the Sahara supply the humid equatorial forests of Central and South America huge amount mineral fertilizers, and the ocean gets the missing piece of iron. At the same time, dust raised in Hawaii makes it possible for banana trees to grow.

What to do if caught in a storm

Having noticed the first signs of an approaching storm, you must immediately stop: continuing to move is useless and a waste of energy, especially since a sandstorm rarely lasts more than four hours. Even if the wind does not subside for about two or three days, it is better to wait in one place and not go anywhere. Therefore, all supplies of water and food must be kept near you (especially water, otherwise complete dehydration of the body is ensured, and this always leads to death).

When you stop, you need to immediately start looking for shelter. It can be a large stone, a boulder, a tree near which you need to lie on the leeward side and completely, with your head, wrap yourself in a cloth. If it is possible to hide in the car, it must be positioned in such a way that the wind does not blow through the doors.

In the worst case, if there is no shelter nearby, you need to lie on the ground and cover your head with clothes (the Bedouins in such cases dig something like a trench). It should be borne in mind that when a sandstorm passes by, the temperature indicators of the air at that moment will be about fifty degrees, which can lead to loss of consciousness. Breathing while tons of sand are sweeping overhead is necessary only through a scarf, otherwise the smallest particles will enter the respiratory tract.

Sandstorm - View from the Airplane

Dust (sand) storm- an atmospheric phenomenon 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 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). 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 occurs during the warm season in desert and semi-desert regions. In addition to the "proper" dust storm, in some cases dust from deserts and semi-deserts can be retained in the atmosphere for a long time and reach almost anywhere in the world in the form of dusty haze.

Less often, dust storms occur in steppe regions, very rarely - in forest-steppe and even forest regions (in the last two zones, a dust storm occurs more often in summer with severe drought). In the 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 even in winter, in combination with snowstorms.

When a certain threshold of wind speed (depending on the mechanical composition of the soil and its moisture content) is exceeded, dust and sand particles detach from the surface and are carried by saltation and suspension, 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 with a height of 0.5-2 m, 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 of occurrence

With an increase in the strength of the wind flow passing over loose particles, the latter begin to vibrate and then "jump". On repeated impacts on the ground, these particles create fine dust that rises in suspension.

Recent research suggests that the initial saltation of sand grains by friction induces electrostatic field . The bouncing particles acquire a negative charge, which releases more particles. This process captures twice as many particles as predicted by previous theories.

Particles are released mainly due to dry soil and increased wind. Wind gust fronts can appear due to air cooling in a rainstorm zone or a dry cold front. After the passage of a dry cold front, the convective instability of the troposphere can contribute to the development of a dust storm. In desert regions, dust and sandstorms are most often caused by thunderstorm downdrafts and the associated increase in wind speed. 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.

Sandstorm in Australia

Ways to fight

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

Environmental impact

Sandstorms can move entire dunes and carry huge amounts of dust, so that the front of the storm can look like a dense wall of dust up to 1.6 km high. Dust and sandstorms coming from the Sahara Desert are also known as samum, hamsin (in Egypt and Israel) and habub (in Sudan).

A large number of dust storms originate in the Sahara, especially in the Bodele Basin and at the convergence of the borders of Mauritania, Mali and Algeria. Over the past half century (since the 1950s), dust storms in the Sahara have increased by about 10 times, 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 a year.

Dust from the Sahara is transported westward across the Atlantic Ocean. Strong daytime heating of the desert creates an unstable layer in the lower part of the troposphere, in which spread dust particles. As the air mass is transported (advected) to the west over the Sahara, it continues to heat up, and then, entering the oceanic expanses, passes over the colder and wetter 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 towards the Atlantic Ocean in June 2007 is five times more than a year earlier, which could cool Atlantic waters and slightly reduce hurricane activity.

Economic implications

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 of deposition - the selva of Central and South America receives most of the mineral fertilizers from the Sahara, makes up for the lack of iron in the ocean, dust in Hawaii helps banana crops grow. In northern China and the western United States, soils with sediment from ancient storms, called loess, are very fertile, but are also a 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 the warm air at the edge of Mars' south polar cap creates strong winds that raise huge clouds of reddish-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.

Notable 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 the army of the Persian king Cambyses.
• In April 1928, in the steppe and forest-steppe regions of Ukraine, the wind raised more than 15 million tons of black soil from an area of ​​1 million km ². The black earth dust was transported to the west and settled on an area of ​​6 million km ² in the Carpathian region, Romania and Poland. The height of the dust clouds reached 750 m, the thickness of the black earth 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 Cauldron period (1930 -1936) forced to move hundreds thousand farmers.
• In second half of the day 8 February 1983 of the year the strongest dusty storm, emerging on the north australian state Victoria, covered town Melbourne.
• V periods multi-year droughts years 1954 —56 , 1976 —78 and 1987 —91 on the territory Northern Of America arose intense dusty storms.
• Strong dusty storm 24 February 2007 of the year, emerging on the territory western Of Texas v district cities Amarillo, covered the whole northern part state. Strong wind caused numerous damage fences, rooftops and even some buildings. Also strongly Suffered international the airport megalopolis Dallas-Fort—Worth, v the hospital applied people With problems at breathing.
• V June 2007 of the year big dusty storm happened v Karachi and on the territory provinces Sindh and Baluchistan, the ensuing per her strong rains led To of death nearly 200 Human .
• 26 May 2008 of the year sandy storm v Mongolia led To of death 46 Human.
• 23 september 2009 of the year dusty storm v Sydney led To interruptions v movement transport and forced hundreds Human to stay Houses. Over 200 Human have applied per medical help from—per problems With breathing.
• 5 july 2011 of the year huge sandy storm covered

Dust (sand) storm- atmospheric phenomenon in the form of transport large quantities dust (soil particles, grains of sand) blown with earth 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 or even several tens of meters). At the same time, dust (sand) rises into the air and at the same time dust settles on large territory... 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 "proper" dust storm, in some cases dust from deserts and semi-deserts can be retained in the atmosphere for a long time and reach almost anywhere in the world in the form of dusty haze.

Dusty haze- atmospheric phenomenon, continuous more or less homogeneous cloudiness of the atmosphere with a horizontal visibility range of 2 m from 1 to 9 km (sometimes visibility decreases to several hundred or even several tens of meters) due to dust and soil particles suspended in the air.
It can be observed before or after a dust storm (when the wind is weakening), as well as during a distant dust storm, when dust particles lifted into the air are carried over a long distance by the wind. At the same time, in the visible vicinity there are no signs of dust lifting by the wind from the surface of the earth. Depending on the color of the soil in a given region, distant objects acquire a grayish, yellowish or reddish tint.
Dust haze should not be confused with dust storm.

Less often, dust storms occur in steppe regions, very rarely - in forest-steppe and even forest (in the last two zones, usually a dust storm occurs in summer with severe drought). V temperate usually dust storms occur in early spring, after a winter with little snow and a dry autumn, but sometimes even in winter, in combination with snowstorms.

The main distribution area of ​​dust storms is deserts and semi-deserts of temperate and tropical climatic zones both hemispheres of the Earth.
The term dust storm is commonly used when a storm occurs over clay and loamy soil. When storms occur in sandy deserts(especially in the Sahara, as well as in the Karakum, Kyzylkum, etc.), when, in addition to small particles reducing visibility, the wind also carries millions of tons of larger sand particles over the surface, the term sandstorm is used.
In Russia, dust storms are most often observed in the Astrakhan region, in the east of the Volgograd region and in Kalmykia.
In a squall (before a thunderstorm and heavy rain), short-term (from several minutes to an hour) local dust storms can be observed in summer period even in points located in the forest vegetation zone- including in Moscow and St. Petersburg (1-3 days per summer).
The Sahara Desert and the Arabian Peninsula Deserts are the main sources of dusty haze in the Arabian Sea region, with Iran, Pakistan and India contributing less. Dust storms in China carry dust into Pacific Ocean.

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". On repeated impacts on the ground, these particles create fine dust that rises in suspension.

Recent research suggests that the initial saltation of the sand grains by friction induces an electrostatic field. The bouncing particles acquire a negative charge, which releases more particles. This process captures twice as many particles as predicted by previous theories.
Particles are released mainly due to dry soil and increased wind. Gust fronts can occur due to air cooling in a rainstorm or dry cold front. After the passage of a dry cold front, the convective instability of the troposphere can contribute to the development of a dust storm. In desert regions, dust and sandstorms are most often caused by thunderstorm downdrafts and the associated increase in wind speed. 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.

Notable dust and sand storms

Dust storm in Australia (September 2009)
- According to the testimony of Herodotus, in 525 BC. e. during a sandstorm in the Sahara, the fifty thousandth army of the Persian king Cambyses perished.
- In April 1928, in the steppe and forest-steppe regions of Ukraine, the wind raised more than 15 million tons of black soil from an area of ​​1 million km². Black earth dust was transported to the west and settled on 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 earth 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 hundreds of thousands of farmers to move.
- On the afternoon of February 8, 1983, the strongest dust storm that appeared in the north of the Australian state of Victoria covered the city of Melbourne.
- During periods of multi-year droughts of 1954-56, 1976-78 and 1987-91 on the territory North America intense dust storms arose.
- A strong dust storm on February 24, 2007, which appeared in the territory of western Texas near the city of Amarillo, covered the entire northern part state. The strong wind caused extensive damage to fences, roofs and even some buildings. The international airport of the Dallas-Fort Worth metropolis was also badly damaged, and people with breathing problems went to the hospital.
- In June 2007, a large dust storm occurred in Karachi and in the provinces of Sindh and Baluchistan, followed by heavy rains that killed almost 200 people.
- On May 26, 2008, a sandstorm in Mongolia killed 46 people.
- On 23 September 2009, a dust storm in Sydney disrupted traffic and forced hundreds of people to stay at home. Over 200 people sought medical help for breathing problems.
- On July 5, 2011, a huge sandstorm covered the city of Phoenix, the capital of the state of Arizona in the United States. The disaster led to breaks in power lines, a fire in the city center, and air traffic was paralyzed.

In particular, I would like to note the historical event named Dusty cauldron.
Dust Bowl, Dust Bowl - a series of catastrophic dust storms that occurred on the prairies of the United States and Canada between 1930 and 1936 (in some regions until 1940). Caused by a combination of anthropogenic (extensive management Agriculture, soil degradation) and natural (drought) factors. The Dusty Cauldron is one of the worst episodes ever American history XX century. In the thirties, a severe economic crisis unfolded in the United States. And suddenly another misfortune was added to it: the country was attacked by terrible dust storms, because of which it was very bad.

The term "Dust Bowl" was first coined on April 15, 1935 by Associated Press reporter Robert Geiger. It is assumed that it comes from the image of the Great Plains, created by William Gilpin: "fertile bowl, rimmed by mountains" (fertile bowl (cauldron) surrounded by mountains). The term is used to designate not only the time of the dust storms of the 1930s, but also the region that became their center: the western third of Kansas, southern Colorado, protruding parts of Texas and Oklahoma, and northern New Mexico.
In 1932, 14 dust storms were recorded, in 1933 - 38. The most violent storms took place in May 1934 and April 1935. Huge masses of soil were blown away by winds that did not encounter obstacles in the devoid of natural vegetation and plowed prairies, and were transported in the form of black clouds over long distances - up to the Atlantic Ocean. April 14, 1935 due to the fact that clouds of dust obscured sunlight, was named Black Sunday. In the winter of 1934-1935, snow fell red with dust in New England. Dust pneumonia has become prevalent among the prairie populations, especially in Kansas and Oklahoma.
By 1934, about 40 million hectares of soils partially or completely lost the upper humus horizon as a result of wind erosion. By 1935, up to 80% of the High Plains area was eroded to one degree or another. By 1938, in Llano Estacado, about 10% of the soil had lost more than 12 cm of the upper horizon, another 13.5% - from 6 to 12 cm.

For many decades, scientists have tried to understand the cause of this phenomenon. In general, the views of experts agree, but there are always many incomprehensible details.

Causes of the Dusty Boiler

The development of the Great Plains began only in the second half of the 19th century, after the adoption of the Homestead Act and the development of the railway network. The main occupation of the settlers was originally animal husbandry, but by 1890, due to overgrazing, there was a transition to agriculture. A new wave of resettlement and a sharp increase in arable land occurs after the First World War, when grain prices rose.
Agriculture of that time developed extensively. Crop rotations were not used, no anti-erosion measures were taken. Moreover, farmers generally burned the stubble and left the field empty for the winter (the period of the most intense winds). As a result, there was a drying out of soils, destruction of their structure, dehumification and a decrease in anti-erosion resistance. The 1930s turned out to be relatively dry, which played a significant role in the development of dust storms.

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. e. 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 for 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 murky veil. A small dark cloud appears on the horizon. It grows rapidly, closing blue sky... Then 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 with 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 sand 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 travel notes the Hungarian explorer of Central Asia A. Vamberi: “In the morning we stopped at a station that bears the cute name of Adamkirilgan (the 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 a 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 emerge from 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 the deserts during the hot season it decreases Atmosphere pressure... 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 Bolshoi 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 more and more thickly. 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 ... Sand hurricane in the town. He breaks trees and poles like matches, tears off the roofs of houses and sheds with a clang. All in captivity of the 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 to the ocean through Dzungaria, the Mongolian plateau, northeast and north of China.

Over the Korean Peninsula and the Soviet The 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 squall forty times a year, then the Mongolian howls sometimes for several days, and in the east of our country it rarely happens more than two or three times a year. Its weakened waves reach Khabarovsk, Ussuriisk, Vladivostok, Komsomolsk and even 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; further it turns gray, and the dark disk 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 air up to 50 degrees or more. The air rushes upward with force. If, in this case, the adjacent sections for any reason turn out to be less heated, then vortices are formed here. As it spirals upwards, the vortex carries with it 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, scatter, are born again. "

The formidable dust vortices are familiar to the North American arid steppes. This is how Mine Reed described them in the novel “The Headless Horseman”: “From the northern side over the prairie, several completely black columns suddenly appeared - there were about ten of them ... bending and bending towards each other, as if in 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 storm 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 o'clock 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 this time of lesser intensity. By the morning of March 11, the storm crossed the Alps and moved north. By the middle of the day it spread to northern Germany and, quickly subsiding, reached Denmark, Baltic Sea and Russia. Total weight the dust that fell during the storm in Europe is approximately equal to 1.8 million tons.

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