What disasters can a sandstorm lead to? dust storms

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

A sure sign that a sandstorm is approaching is a sudden silence when the wind stops blowing, and with it all sounds and rustles disappear. Instead, stuffiness intensifies, and along with it, anxiety emerges at a subconscious level. And after a while, a fast-growing black-purple cloud appears on the horizon. The wind appears again and, picking up speed, raises dust and sand.

A sandstorm, or as it is also called, a dust storm is an atmospheric phenomenon when a strong wind moves 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 ground becomes reddish, yellowish or greyish (depending on the composition of the airborne particles). Despite the fact that dust storms appear mainly in summer, in the absence of precipitation and rapid drying of the soil, they also occur in winter.

Dust storms form 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, Khmelnytsky, a city located in western Ukraine, was hit by a sandstorm. The hurricane lasted about five minutes, visibility did not exceed ten meters, and the wind was so strong that it almost carried people and vehicles off the bridges.

How a storm is formed

In order for a dust storm to arise, a dry ground surface and a wind speed exceeding 10 m / s are required (for example, in the Sahara, its rates often reach 50 m / s). Dust storms appear due to the turbulence (heterogeneity) of air flows, which, when moving over an uneven surface, collide with obstacles, form air turbulences. The faster the wind moves, the more dangerous eddies it creates.

After the movement of air masses over loose particles of soil increases, 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 turn into fine dust.

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

Whereas smaller particles earth's surface fly extremely high, large ones rise to a lower distance and fall quickly (if the wind is extremely strong, the dust can be transported 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.

In order for a dust storm to form, the soil must be dry: in the event of a prolonged drought, under the influence of strong winds, even particles of the upper layers of chernozem soil can rise into the air (in this case, a “black storm” is formed), and move 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 suddenly appeared, lifted up more than 15 million tons of black soil (the height of the cloud was 750 m) and moved them thousands of kilometers to the side. Some of the dust settled in the Carpathians, 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 event last

Sandstorms typically last between thirty minutes and 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 short-term dust storms, there are also such dust storms during which visibility is limited to two tens of meters.

A dust storm always appears almost unexpectedly: in good weather, a heavy wind will rise, as a result of which the speed of air flows 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. You can tell that a dust storm is approaching by the gray foggy veil that appears under cumulonimbus clouds when they are close to the horizon.

There are also long sandstorms:

• Some dust storms are characterized by only a partial deterioration in visibility, up to four kilometers (however, these dust storms are the longest in time, since they can last several days).
• Others are characterized by limited visibility to a few meters on initial stage 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 (about eighty storms sweep through Mauritania alone in a year).

The uplifted sand of the Sahara is so abundant that a huge amount 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 along with the air, after which, once above the ocean, they pass under a colder and more humid air stream. The difference in temperature between the layers of air causes them to not mix with each other, allowing dusty warm air to cross the ocean.

Although sandstorms cause many negative consequences(destroy the fertile soil layer, adversely affect respiratory system living organisms), the dust raised into the air also brings benefits. For example, dust storms in the Sahara supply humid equatorial forests Central and South America a huge amount of mineral fertilizers, and the ocean receives the missing part of the iron. At the same time, the 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: it is useless to continue moving and extra waste forces, 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).

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

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, the air temperature at that moment will be about fifty degrees, which can lead to loss of consciousness. Breathe while tons of sand are sweeping over your head, you only need to use a handkerchief, otherwise the smallest particles will enter the respiratory tract.

Sandstorm - view from the plane

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 drop 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 take on a grayish, yellowish, or reddish hue. 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 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 a dust 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 (rarely) 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 snowstorms.

When a certain threshold of wind speed is exceeded (depending on the mechanical composition of the soil and its moisture), dust and sand particles break off from 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 repeatedly hitting the ground, these particles create fine dust that rises as a suspension.

A recent study suggests that the initial saltation of sand grains by friction induces electrostatic field . Jumping particles acquire a negative charge, which releases even more particles. Such a process captures twice as many particles as previous theories predict.

Particles are released mainly due to the dryness of the soil and increased wind. Fronts of gusts of wind can appear due to the cooling of the air in the zone 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 sandstorms are most commonly caused by thunderstorm downdrafts and the associated increase in wind speeds. The vertical dimensions of the storm are determined by the stability of the atmosphere and the weight of the particles. In some cases, dust and sandstorms can be limited 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 agrotechnical practices such as grass seeding , crop rotation and contour plowing .

Environmental consequences

Sandstorms can move entire dunes and carry huge amounts of dust, so that the front of the storm 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 samum, khamsin (in Egypt and Israel) and habub (in Sudan).

A large number of dust storms originate in the Sahara, especially in the Bodele depression and in the area where the borders of Mauritania, Mali and Algeria converge. 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 per year.

Dust from the Sahara is transported across the Atlantic Ocean to the west. 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 transfers (advection) to the west over the Sahara, it continues to heat up, and then, having entered the ocean, passes over a colder and wetter atmospheric layer. This temperature inversion keeps the layers from mixing and allows the dusty layer of air to cross the ocean. The volume of dust blown out of the Sahara towards the Atlantic Ocean in June 2007 is five times greater than a year earlier, which could cool the waters of the Atlantic and slightly reduce hurricane activity.

Economic consequences

The main damage caused by dust storms is the destruction of the fertile soil layer, which reduces it. agricultural productivity . In addition , the abrasive effect damages young plants . Other possible negative effects include: reduced visibility affecting air and road transport; a decrease in the amount of sunlight reaching the Earth's surface; the effect of a thermal "cover"; unfavorable impact on the respiratory system of living organisms.

Dust can also be beneficial in places of deposition - the rainforest of Central and South America receives most of the mineral fertilizers from the Sahara, the lack of iron in the ocean is replenished, the 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 soil-binding vegetation is disrupted.

extraterrestrial dust storms

The strong difference in temperature between the ice sheet and the warm air at the edge of Mars' south polar cap results in strong winds that kick up 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 heats the atmosphere due to this.

Known dust and sandstorms

Dust storm in Australia (September 2009)

• According to Herodotus, in 525 BC e . killed in 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 raised more than 15 million tons of black soil from an area of ​​1 million km². Chernozem dust was transported to the west and settled on an area of ​​6 million km² in the Carpathian region, in Romania and in Poland. The height of dust clouds reached 750 m, the thickness of the chernozem 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 hundreds thousand farmers.
• In second half days 8 February 1983 of the year the strongest dusty storm, emerging on the north Australian state Victoria, covered city Melbourne.
• AT periods multi-year droughts years 1954 —56 , 1976 —78 and 1987 —91 on the territory Northern America arose intense dusty storms.
• strong dusty storm 24 February 2007 of the year, emerging on the territory western Texas in area cities Amarillo, covered all northern part state. Strong wind caused numerous damage fences, roofs and even some buildings. Also strongly Suffered international the airport metropolis Dallas-Fort—Worth, in hospital applied people with problems at breathing.
• AT June 2007 of the year big dusty storm happened in Karachi and on the territory provinces Sindh and Balochistan, subsequent behind her strong rains led to of death almost 200 Human .
• 26 May 2008 of the year sandy storm in Mongolia led to of death 46 Human.
• 23 September 2009 of the year dusty storm in Sydney led to interruptions in movement transport and forced hundreds Human stay Houses. Over 200 Human turned behind medical help from—behind problems with breath.
• 5 July 2011 of the year huge sandy storm covered

Sandstorms - samums - have long been covered with a gloomy halo. It is not for nothing that they bear this name - “samum” means poisonous, poisoned. And such storms really ruined entire caravans. Samum observed in deserts North Africa and the Arabian Peninsula and most often has a western and southwestern direction. It mostly happens in spring and summer.

(Total 15 photos)

“An hour or half an hour before the merciless storm rises, bright sun dim, clouded over with a muddy veil. A small dark cloud appears on the horizon. It grows rapidly, covering the blue sky. Here came the first furious gust of hot, prickly wind. And in a minute the day fades. Clouds of burning sand mercilessly cut through all living things, cover the midday sun. In the howl and whistle of the wind, all other sounds disappear. It seems that the air itself is turning against you ... ”- This is the description of a sandstorm given by the ancient Greek historian Herodotus

Nowadays, when the desert is crossed by highways, and air routes run over them in all directions, death on the great caravan routes no longer threatens travelers.

So, in 1805, samum, according to many authors, covered two thousand people and one thousand eight hundred camels with sand. And it is quite possible that the same storm killed in 525 BC. the army of the Persian king Cambyses, about which Herodotus wrote

It happens that the testimonies of people who have endured the test of the elements sin with exaggerations. However, of course - the samum is very dangerous.

Fine sandy dust, which is raised by a strong wind, penetrates into the ears, eyes, nasopharynx, lungs

Saving lives, people lie down 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.

Many desert storms owe their birth to passing cyclones that affect deserts as well. There is another reason - in the deserts during the hot season decreases Atmosphere pressure. Hot sands strongly heat the air near the surface of the earth. As a result, it rises, and streams of colder dense air rush in its place at very high speeds. Small local cyclones form, giving rise to sandstorms.

According to ecologists, last years sandstorms are ten times more common than they were fifty years ago... Mauritania alone, which had no more than two sandstorms a year in the early sixties, now has over eighty...

Dust (sand) storms

Dust storms - transfer a large number dust and sand by strong and prolonged winds blowing the upper layers of the soil. Compared to earthquakes or tropical cyclones dust storms are not, in fact, such catastrophic phenomena, but their impact can be very unpleasant, and sometimes fatal.

How does a dust storm occur? A wedge of cold air invades under a layer of warm air. Moving quickly, it lifts a lot of solid particles into the air. They are deposited at a distance of many kilometers.

Dust storms are a phenomenon, although meteorological, but associated with the state soil cover and with the terrain. They are akin to snowstorms: for the occurrence of both of them, a strong wind is needed and enough dry material on the surface of the earth that can rise into the air and long time be there in balance. But if for the appearance of blizzards you need dry, non-packed, snow-free snow lying on the surface and a wind speed of 7-10 m / s or more, then for the occurrence of dust storms it is necessary that the soil be loose, dry, devoid of grass or any significant snow cover and wind speed was not less than 15 m/s. Dust storms are most common in early spring, in March or April, after a dry autumn and a 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 danger of this phenomenon also lies in the terrible force of the wind and its extraordinary impetuousness. 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 on impact with 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 earth can lead to the destruction of buildings, windbreaks, not to mention the all-penetrating dust that fills houses, soaks people’s clothes, covers their eyes, makes it difficult to breathe, then it becomes clear how dangerous this phenomenon is and why it is called spontaneous. disaster. Dust storms usually last several hours, but in some cases - 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.

Wind during dust storms carries not only dust, but also sand and even small gravel. Above the earth's surface itself, crushed stone and coarse sand fly, at a height of several tens of meters - fine sand, and even higher - a dark, dense cloud of dust. The width of this dust-sand flow is several hundred kilometers, the speed of movement is 40-60 km/h.

Protection. The rules in the desert are as follows: when in a car, you must close the windows and stay inside the car. If there is no shelter nearby, you need to lie in the direction opposite to the wind, facing the ground, cover with your head. The dust storm does not represent mortal danger. The main thing is to keep calm.

These climatic phenomena make a significant contribution to the pollution of the earth's atmosphere. It is one of the many incredible natural phenomena, which scientists quickly found a simple explanation.

These adverse climatic events are dust storms. They will be discussed in more detail in the following article.

Definition

A dust, or sand, storm is a phenomenon of the transfer of a huge amount of sand and dust by strong winds, which is accompanied by sharp deterioration visibility. As a rule, such phenomena originate on land.

This is arid regions planets from where air currents carry powerful clouds of dust into the ocean. Moreover, while representing a considerable danger to humans, mainly on land, they still greatly impair transparency. atmospheric air, making it difficult to observe the surface of the ocean from space.

It's all about the terrible heat, due to which the soil dries out a lot and then breaks up into microparticles in the surface layer, picked up by a strong wind.

But dust storms begin at certain critical values ​​\u200b\u200bdepending on the terrain and soil structure. For the most part they start at wind speeds in the range of 10-12 m/s. And weak dust storms occur in summer even at speeds of 8 m/s, less often at 5 m/s.

Behavior

The duration of storms varies from minutes to several days. Most often, time is measured in hours. For example, an 80-hour storm was recorded in the Aral Sea area.

After the disappearance of the causes of the described phenomenon, the dust raised from the surface of the earth remains in the air in a suspended state for several hours, possibly even days. In these cases, its huge masses are carried by air currents for hundreds and even thousands of kilometers. Dust carried by the wind over long distances from the source is called advective haze.

tropical air masses this mist is transferred to southern part Russia and all of Europe from Africa (its northern regions) and the Middle East. And western flows often carry such dust from China (center and north) to the Pacific coast, etc.

Colour

Dust storms have a wide variety of colors, which depend on their color. There are storms of the following colors:

• black (chernozem soils of the southern and southeastern regions of the European part of Russia, the Orenburg region and Bashkiria);
• yellow and brown (typical of the USA and Central Asia- loam and sandy loam);
• red (red-colored, iron oxide-colored soils of the desert areas of Afghanistan and Iran;
• white (salt marshes of some regions of Kalmykia, Turkmenistan and the Volga region).

Geography of storms

The occurrence of dust storms occurs in completely different places planets. The main habitat are semi-deserts and deserts of tropical and temperate climatic zones, and both hemispheres.

Usually the term "dust storm" is used when it occurs over loamy or clayey soil. When does it occur in sandy deserts(for example, in the Sahara, Kyzylkum, Karakum, etc.), and, in addition to the smallest particles, the wind carries through the air millions of tons and larger particles (sand), the term "sandstorm" is already used.

Dust storms often occur in the Balkhash and Aral regions (south of Kazakhstan), in the western part of Kazakhstan, on the Caspian coast, in Karakalpakstan and in Turkmenistan.

Where are dusty Most often they are observed in the Astrakhan and Volgograd regions, in Tyva, Kalmykia, as well as in the Altai and Trans-Baikal Territories.

During periods of prolonged drought, storms can develop (not every year) in the forest-steppe and steppe zones Chita, Buryatia, Tuva, Novosibirsk, Orenburg, Samara, Voronezh, Rostov regions, Krasnodar, Stavropol territories, in the Crimea, etc.

The main sources of dust haze in Arabian Sea are the peninsulas and the Sahara. Storms from Iran, Pakistan and India bring less damage in these places.

AT Pacific Ocean dust is carried by Chinese storms.

Ecological consequences of dust storms

The described phenomena are able to move huge dunes and carry large volumes of dust in such a way that the front can be represented as a dense and high wall of dust (up to 1.6 km.). The storms that come from the Sahara desert are known as Samoom, Khamsin (Egypt and Israel) and Khabub (Sudan).

For the most part in the Sahara, storms occur in the Bodele depression and at the junction of the borders of Mali, Mauritania and Algeria.

It should be noted that over the past 60 s extra years the number of dust storms in the Sahara increased by about 10 times, which caused a significant decrease in the thickness of the surface layer of soil in Chad, Niger, Nigeria. For comparison, it can be noted that in Mauritania in the 60s of the last century there were only two dust storms, and today there are 80 storms a year there.

Environmental scientists believe that an irresponsible attitude towards the arid regions of the Earth, in particular, ignoring the crop rotation system, steadily leads to an increase in desert areas and a change in the climatic state of planet Earth at the global level.

Ways to fight

Dust storms, like many others, cause great harm. In order to reduce and even prevent their negative consequences, it is necessary to analyze the features of the terrain - the relief, the microclimate, the direction of the winds prevailing here, and take appropriate measures that will help reduce the wind speed near the earth's surface and increase the adhesion of soil particles.

To reduce the wind speed, certain measures are taken. Systems of wind-shelter wings and forest belts are being created everywhere. Non-moldboard plowing, abandoned stubble, crops of perennial grasses, strips of perennial grasses interspersed with crops of annual crops have a significant effect on increasing the adhesion of soil particles.

Some of the most famous sand and dust storms

For example, we offer you a list of the most famous sand and dust storms:

• In 525 BC. e., according to Herodotus, in the Sahara during a sandstorm, the 50,000th army of the king of Persia Cambyses died.
• In 1928, in Ukraine, a terrible wind raised more than 15 million tons of black soil from an area equal to 1 million km², the dust of which was transferred to the Carpathian region, Romania and Poland, where it settled.
• In 1983, the strongest storm in the north of Victoria, Australia covered the city of Melbourne.
• In the summer of 2007, a severe storm hit Karachi and the provinces of Balochistan and Sindh, and the heavy rains that followed resulted in the death of about 200 people.
• In May 2008, a sandstorm in Mongolia killed 46 people.
• In September 2015, a terrible "sharav" (sand storm) swept through larger area Middle East and North Africa. Israel, Egypt, Palestine, Lebanon, Jordan, Saudi Arabia and Syria. There were also human casualties.

In conclusion, a little about extraterrestrial dust storms

Martian dust storms occur in the following way. Due to the strong difference in temperature between the ice layer and warm air on the outskirts of the southern polar cap of the planet Mars, there are strong winds, raising huge clouds of red-brown dust. And here there are certain consequences. Scientists believe that the dust of Mars can play about the same role as the earth's clouds. The atmosphere is heated by the absorption of sunlight by dust.