Introduction……………………………………………………………………….3

1. Ice……………………………………………………………………...5

2. Fog ………………………………………………………………………….7

3. City……………………………….…………………………………………...8

4. Thunderstorm.……………………………………………………………… ..............9

5. Hurricane………………………………………………..……………………..17

6. Storm……………………………………………………………………… … ...17

7. Tornado………………………………………………………………………..19

Conclusion……………………………………………………………….........22

List of used literature………………………………………...23

Introduction

The gaseous medium around the Earth, rotating with it, is called the atmosphere.

Its composition at the Earth's surface: 78.1% nitrogen, 21% oxygen, 0.9% argon, in small fractions of a percent carbon dioxide, hydrogen, helium, neon and other gases. The lower 20 km contains water vapor (3% in the tropics, 2 x 10-5% in Antarctica). At an altitude of 20-25 km, there is an ozone layer that protects living organisms on Earth from harmful short-wave radiation. Above 100 km, gas molecules decompose into atoms and ions, forming the ionosphere.

Depending on the distribution of temperature, the atmosphere is divided into the troposphere, stratosphere, mesosphere, thermosphere, exosphere.

Uneven heating contributes to the general circulation of the atmosphere, which affects the weather and climate of the Earth. The strength of the wind at the earth's surface is estimated on the Beaufort scale.

Atmospheric pressure is distributed unevenly, which leads to the movement of air relative to the Earth from high pressure to low pressure. This movement is called wind. The area of ​​low pressure in the atmosphere with a minimum in the center is called a cyclone.

The cyclone in diameter reaches several thousand kilometers. In the Northern Hemisphere, winds in a cyclone blow counterclockwise, while in the Southern Hemisphere, they blow clockwise. The weather during the cyclone is overcast, with strong winds.

An anticyclone is an area of ​​high pressure in the atmosphere with a maximum in the center. The diameter of the anticyclone is several thousand kilometers. The anticyclone is characterized by a system of winds blowing clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere, cloudy and dry weather and light winds.

The following electrical phenomena take place in the atmosphere: air ionization, the electric field of the atmosphere, electric charges of clouds, currents and discharges.

Atmospheric hazards are dangerous natural, meteorological processes and phenomena that occur in the atmosphere under the influence of various natural factors or their combinations, which have or may have a damaging effect on people, farm animals and plants, economic facilities and the environment. Atmospheric natural phenomena include: strong wind, whirlwind, hurricane, cyclone, storm, tornado, squall, prolonged rain, thunderstorm, downpour, hail, snow, ice, frost, heavy snowfall, heavy snowstorm, fog, dust storm, drought, etc. . one

  1. ice

Ice (GOST R 22.0.03-95) is a layer of dense ice on the earth's surface and on objects as a result of freezing of drops of supercooled rain, drizzle or heavy fog, as well as during condensation of steam. It occurs at temperatures from 0 ° to -15 "C. 2 Precipitation falls in the form of supercooled drops, but when in contact with the surface or objects, they freeze, covering it with an ice layer. A typical situation for the occurrence of ice is the arrival in winter after severe frosts of relatively warm and humid air, which most often has a temperature of 0 ° to -3 ° C. Sticking of wet snow (snow and ice crusts), the most dangerous for communication lines and power lines, occurs during snowfalls and temperatures from + Г to -3 ° С and wind speed 10 -20 m / s. The danger of ice increases sharply with wind intensification. This leads to a break in power wires. The heaviest ice in Novgorod was observed in the spring of 1959, it caused massive damage to communication lines and power lines, as a result of which communications with Novgorod were The ice-crusted surface of pavements and sidewalks during icy conditions causes numerous injuries, as well as road accidents. about transport. On the roadbed, a roll is formed, paralyzing traffic, like ice. These phenomena are typical for coastal regions with a humid mild climate (Western Europe, Japan, Sakhalin, etc.), but are also common in inland regions at the beginning and end of winter. When supercooled fog drops freeze on various objects, icy (at temperatures from 0° to -5°, less often -20°С) and frosty (at temperatures from -10° to -30°, less often -40°С) crusts are formed. The weight of ice crusts can exceed 10 kg/m (up to 35 kg/m in Sakhalin, up to 86 kg/m in the Urals). Such a load is devastating for most wire lines and for many masts. In addition, there is a high probability of aircraft icing along the front of the fuselage, on propellers, wing ribs and protruding parts of the aircraft. Aerodynamic properties deteriorate, vibrations occur, accidents are possible. Icing occurs in supercooled water clouds with temperatures ranging from 0° to -10°C. Upon contact with the aircraft, the drops spread and freeze, snowflakes from the air freeze to them. Icing is also possible when flying under clouds in a zone of supercooled rain. Especially dangerous is icing in frontal clouds, since these clouds are always mixed, and their horizontal and vertical dimensions are comparable to those of fronts and air masses.

Distinguish ice transparent and cloudy (opaque). Cloudy ice occurs with smaller drops (drizzle) and at lower temperatures. Hoarfrost occurs due to the sublimation of steam.
Ice is abundant in the mountains and in maritime climates, for example, in southern Russia and Ukraine. Glaze recurrence is highest where fogs are frequent at temperatures from 0° to -5°C.
In the North Caucasus, in January 1970, ice weighing 4-8 kg/m3 and a deposit diameter of 150 mm formed on the wires, as a result, many power lines and communications were destroyed. Severe icing has been noted in the Donets basin, in the Southern Urals, etc. The impact of icing on the economy is most noticeable in Western Europe, the USA, Canada, Japan, and in the southern regions of the former USSR. So, in February 1984 in Stavropol, ice with wind paralyzed roads and caused an accident on 175 high-voltage lines (for 4 days).

Fog is an accumulation of small water droplets or ice crystals, or both, in the surface layer of the atmosphere (sometimes up to a height of several hundred meters), reducing horizontal visibility to 1 km or less.

In very dense fog, visibility can drop to several meters. Fogs are formed as a result of condensation or sublimation of water vapor on aerosol (liquid or solid) particles contained in the air (the so-called condensation nuclei). Most fog droplets have a radius of 5-15 microns at positive air temperature and 2-5 microns at negative temperatures. The number of drops in 1 cm3 of air ranges from 50-100 in weak fogs to 500-600 in dense ones. Fogs are divided into cooling fogs and evaporation fogs according to their physical genesis.

According to the synoptic conditions of formation, intra-mass fogs are distinguished, which form in homogeneous air masses, and frontal fogs, the appearance of which is associated with atmospheric fronts. Intramass fogs predominate.

In most cases, these are cooling fogs, and they are divided into radiative and advective. Radiation fogs are formed over land when the temperature drops due to radiative cooling of the earth's surface, and from it the air. Most often they are formed in anticyclones. Advective fogs form when warm, moist air cools as it moves over colder land or water. Advective fogs develop both over land and over the sea, most often in the warm sectors of cyclones. Advective fogs are more stable than radiative ones. Frontal fogs form near atmospheric fronts and move with them. Fog interferes with the normal operation of all modes of transport. Fog forecast is essential in safety.

A hailstone is a type of atmospheric precipitation consisting of spherical particles or pieces of ice (hailstones) ranging in size from 5 to 55 mm, there are hailstones 130 mm in size and weighing about 1 kg. The density of hailstones is 0.5-0.9 g/cm3. In 1 minute, 500-1000 hailstones fall on 1 m2. The duration of hail is usually 5-10 minutes, very rarely - up to 1 hour. 3

Hail falls during the warm season, its formation is associated with violent atmospheric processes in cumulonimbus clouds. Ascending air currents move water droplets in a supercooled cloud, the water freezes and freezes into hailstones. Upon reaching a certain mass, hailstones fall to the ground.

Hail poses the greatest danger to plants - it can destroy the entire crop. There are known cases of people dying from hail. The main preventive measures are protection in a safe shelter.

Radiological methods have been developed to determine the hail and hail hazard of clouds, and operational hail control services have been created. Hail control is based on the principle of introducing a reagent (usually lead iodide or silver iodide) into the cloud using rockets or shells, which helps to freeze supercooled droplets. As a result, a huge number of artificial crystallization centers appear. Therefore, the hailstones are smaller and they have time to melt before falling to the ground.

A thunderstorm is an atmospheric phenomenon associated with the development of powerful cumulus clouds, the occurrence of electrical discharges (lightning), accompanied by a sound effect (thunder), squally wind increase, downpour, hail, and a decrease in temperature. The strength of a thunderstorm directly depends on the air temperature - the higher the temperature, the stronger the thunderstorm. Thunderstorms can last from a few minutes to several hours. Thunderstorm refers to fast-moving, stormy and extremely dangerous atmospheric natural phenomena.

Signs of an approaching thunderstorm: rapid development in the afternoon of powerful, dark cumulus rain clouds in the form of mountain ranges with anvil tops; a sharp decrease in atmospheric pressure and air temperature; exhausting stuffiness, calmness; calm in nature, the appearance of a veil in the sky; good and distinct audibility of distant sounds; approaching thunder, flashes of lightning.

The damaging factor of a thunderstorm is lightning. Lightning is a high-energy electrical discharge that occurs due to the establishment of a potential difference (of several million volts) between the surfaces of clouds and the earth. Thunder is the sound in the atmosphere that accompanies lightning. Caused by air fluctuations under the influence of an instant increase in pressure in the path of lightning.

Most often, lightning occurs in cumulonimbus clouds. The American physicist B. Franklin (1706-1790), Russian scientists M.V. Lomonosov (1711-1765) and G. Richmann (1711-1753), who died from a lightning strike while studying atmospheric electricity, contributed to the disclosure of the nature of lightning. Lightning are linear, ball, flat, bag-shaped (Fig. 1).

Characteristics of linear zipper:

length - 2 - 50 km; width - up to 10 m; current strength - 50 - 60 thousand A; propagation speed - up to 100 thousand km / s; temperature in the lightning channel - 30,000°C; lightning lifetime - 0.001 - 0.002 s.

Lightning most often hits: a tall stand-alone tree, a haystack, a chimney, a tall building, a mountain top. In the forest, lightning often strikes oak, pine, spruce, less often birch, maple. Lightning can cause fire, explosion, destruction of buildings and structures, injury and death of people.

Lightning strikes a person in the following cases: direct hit; the passage of an electric discharge in the immediate vicinity (about 1 m) from a person; distribution of electricity in damp earth or water.

Rules of conduct in the building: tightly close windows, doors; disconnect electrical appliances from power sources; turn off the outdoor antenna; stop telephone conversations; do not stay at the window, near massive metal objects, on the roof and in the attic.
In the woods:

not to be under the crowns of tall or stand-alone trees; do not lean against tree trunks; do not sit near a fire (a column of hot air is a good conductor of electricity); do not climb tall trees.

In the open: go into cover, do not form a tight group; don't be the highest point in the neighborhood; do not stay on hills, near metal fences, power lines and under wires; do not go barefoot; do not hide in a haystack or straw; Do not lift conductive objects over your head.

do not swim during a thunderstorm; do not stay in close proximity to the reservoir; don't go boating; don't fish.

To reduce the likelihood of being struck by lightning, the human body should have as little contact with the ground as possible. The safest position is the following: sit down, put your feet together, put your head on your knees and wrap your arms around them.

Ball lightning. There is no generally accepted scientific interpretation of the nature of ball lightning yet; its connection with linear lightning has been established by repeated observations. Ball lightning can appear unexpectedly anywhere, it can be spherical, egg-shaped and pear-shaped. The dimensions of ball lightning often reach the size of a soccer ball, lightning moves in space slowly, with stops, sometimes it explodes, calmly fades, breaks into pieces or disappears without a trace. Ball lightning "lives" for about one minute, during its movement a slight whistle or hiss is heard; sometimes it moves silently. The color of ball lightning is different: red, white, blue, black, mother-of-pearl. Sometimes ball lightning rotates and sparks; due to its plasticity, it can penetrate the premises, the interior of the car, the trajectory of its movement and behavior are unpredictable.

Dangerous phenomena of the winter period

The atmosphere of the Earth has a great influence on the life and activities of people. Those phenomena that occur in it and are observed on the planet either represent a danger or impede the functioning of human systems. Fog, lightning, hurricanes, storms, tornadoes, hail, etc. can be considered such dangerous phenomena. Hazardous atmospheric phenomena can arise unexpectedly, appear as spontaneous ones, and therefore cause significant damage. Hazardous phenomena are associated with the peculiarities of atmospheric circulation, and sometimes with the terrain. The winter period is characterized by such dangerous phenomena as snowfalls, blizzards, frosts, black ice, etc.

Definition 1

Snowfall- Intensive snowfall, leading to reduced visibility and difficulty in traffic.

Such an emergency situation as a snowfall ranks $4$-$5$ in the world in terms of damage, but sometimes moves to $3$-$4$ place. Under the action of snow loads, roofs of houses can break, trees fall, plantations die, etc. Average snow loads from the maximum can exceed $ 250 kg / m3. As a result of snowfalls, large cities can be paralyzed in a matter of hours. For example, in $1967$ in Chicago$58$ cm of snow fell. The inhabitants of the city remembered him as "Snowstorm of '67". The strength of this snowfall hit the Midwest of the United States and covered the territory from Michigan to Indiana. This snowstorm claimed the lives of $76$ people.

In $1971$, heavy snowfall began in Canada, in the provinces of Ontario and Quebec, where $61$ cm of snow fell in a short period. The storm was named East Canadian Blizzard of '71" and accompanied by strong winds. Visibility on the roads was zero. The very low temperature caused the death of $20$ people, and for the locals it was a real disaster.

Tibet$2008$ Due to the high altitude, it is cool here and there is little snow, but $2008$ was an exception for local residents. Heavy snowfall lasted $36$ hours and covered some areas with snow, $180$ cm thick. Its average thickness was $150$ cm. Buildings could not withstand, roads did not function.

US city sets record for snowfall Buffalo in $1977$. Compared to the surrounding areas, there are higher temperatures and less snowfall in winter. The snowfall of $1977$ was quite moderate, but with a very strong wind, the speed of which was $70$ km per hour. At this point, there was already a layer of snow in the city. Not the strongest snow storm caused a terrible frost, zero visibility and a snowstorm. After the end of the snowfall in the city, the layer of snow that fell was $5$ meters - it was an absolute record season.

Dangerous phenomena of the summer period

For the summer period, there are dangerous natural phenomena associated with the atmosphere - these are heat, dry winds, droughts. They also include natural fires, floods, tornadoes, tornadoes, whirlwinds, etc.

Definition 2

Tornado- this is an ascending vortex of rapidly rotating air with particles of sand, dust, moisture

Over the sea such a whirlwind is called tornado, and over land - blood clots. In North America, blood clots are called tornado. This is an air funnel hanging from a cloud in the form of a trunk and falling to the ground. Tornadoes are formed in different parts of the planet and can be accompanied by thunderstorms and heavy showers. They can occur both over land and over water.

The birth of a tornado is associated with low cumulonimbus clouds, in the form of a dark funnel descending to the ground, but can also appear in clear weather. A tornado cloud occupies $5$-$10$ km across, sometimes even $15$ km. Its height is $4$-$5$ km, sometimes it can be $15$ km. There is usually a short distance between the surface of the earth and the base of the cloud. At the base of the mother cloud there is a collar cloud, the upper surface of which is located at a height of up to $1500$ m. The tornado itself hangs from the lower surface of the wall cloud lying under the collar cloud. Like a pump, a tornado sucks various objects into the cloud, which, falling into the vortex ring, are held in it and transported for tens of kilometers.

The main part of the tornado is funnel, which is a spiral vortex. The movement of air in the walls of the tornado goes in a spiral at a speed of about $ 200 $ m/s. Various objects, even people and animals caught in a tornado, rise up in the walls, and not along an empty internal cavity. Dense tornadoes have a small wall thickness compared to the width of the cavity. The air in the funnel can reach high speeds from $600-$1000 km/h. There are such whirlwinds of minutes, less often there are tens of minutes. One cloud can form entire groups of tornadoes. Tornadoes can travel from hundreds of meters to hundreds of kilometers. Their average speed is $50$-$60$ km/h. For them, the seas, lakes, forests, hills are not an obstacle. Having passed through the ground, a tornado can rise into the air without touching it and then descend again. The destructive power of the tornado is great - it tears up power supply and communication lines, disables equipment, destroys residential and industrial buildings, and leads to human casualties.

Within Russia, tornadoes are most often formed in the central regions, in the Volga region, in the Urals and Siberia. Tornadoes often form on the seas and, going out to the coast, increase their strength. It is almost impossible to predict the time and place of the appearance of a tornado; they arise mostly suddenly. Statistics speak of tornadoes near Arzamas, Murom, Kursk, Vyatka, Yaroslavl.

In Europe, these dangerous phenomena are rare, and they can be observed in hot summer weather. In the north, they were noted in southern Norway, Sweden, the Solovetsky Islands, in Siberia - up to the lower reaches of the Ob. Losses from these atmospheric phenomena amount to millions of dollars and, most importantly, human lives.

Rules of conduct for various atmospheric phenomena

Certain atmospheric phenomena cause damage not only to the economy, but also to the death of people. From this point of view, people should know the rules - how to behave in an unusual situation so as not to die.

Rules of conduct for snow drifts:

  1. With skid warning - restrict movement;
  2. Create a supply of food, water;
  3. Ropes are stretched between houses;
  4. In cars, close the blinds, cover the engine from the side of the radiator;
  5. You can not leave the car, so as not to lose the landmark;
  6. In rural areas, prepare food for animals;
  7. You can not be in dilapidated buildings, under power lines, under trees.

Of course, there is no special “recipe” for a tornado, but precautions will help in this situation.

Rules of conduct during a tornado:

  1. In private houses, it is necessary to check the fastening of the roof;
  2. Remove light objects from the open space - boxes, barrels;
  3. Close all windows and doors;
  4. Cut off the supply of water, gas and electricity;
  5. Go down to the basement.

Rules of conduct during a storm and thunderstorm:

  1. Disconnect electrical appliances from the power supply;
  2. Do not hold metal objects in your hands;
  3. Do not stand with them at an open window;
  4. Close windows and doors;
  5. Be in the center of the room;
  6. Stop the car in some lowland, if possible;
  7. Leave the car, do not run;
  8. You can not hide under trees, especially under larches and oaks;
  9. In the forest, the tent should stand in a low place;
  10. Wet things attract lightning;
  11. You can hide among low-growing trees;
  12. Clay soil increases the danger;
  13. You can not approach metal pipes and dilapidated buildings;

Thunderstorms often go against the wind. Before a thunderstorm, there is complete calm or the wind changes direction abruptly.

Dangerous phenomena of the winter period

The atmosphere of the Earth has a great influence on the life and activities of people. Those phenomena that occur in it and are observed on the planet either represent a danger or impede the functioning of human systems. Fog, lightning, hurricanes, storms, tornadoes, hail, etc. can be considered such dangerous phenomena. Hazardous atmospheric phenomena can arise unexpectedly, appear as spontaneous ones, and therefore cause significant damage. Hazardous phenomena are associated with the peculiarities of atmospheric circulation, and sometimes with the terrain. The winter period is characterized by such dangerous phenomena as snowfalls, blizzards, frosts, black ice, etc.

Definition 1

Snowfall- Intensive snowfall, leading to reduced visibility and difficulty in traffic.

Such an emergency situation as a snowfall ranks $4$-$5$ in the world in terms of damage, but sometimes moves to $3$-$4$ place. Under the action of snow loads, roofs of houses can break, trees fall, plantations die, etc. Average snow loads from the maximum can exceed $ 250 kg / m3. As a result of snowfalls, large cities can be paralyzed in a matter of hours. For example, in $1967$ in Chicago$58$ cm of snow fell. The inhabitants of the city remembered him as "Snowstorm of '67". The strength of this snowfall hit the Midwest of the United States and covered the territory from Michigan to Indiana. This snowstorm claimed the lives of $76$ people.

In $1971$, heavy snowfall began in Canada, in the provinces of Ontario and Quebec, where $61$ cm of snow fell in a short period. The storm was named East Canadian Blizzard of '71" and accompanied by strong winds. Visibility on the roads was zero. The very low temperature caused the death of $20$ people, and for the locals it was a real disaster.

Tibet$2008$ Due to the high altitude, it is cool here and there is little snow, but $2008$ was an exception for local residents. Heavy snowfall lasted $36$ hours and covered some areas with snow, $180$ cm thick. Its average thickness was $150$ cm. Buildings could not withstand, roads did not function.

US city sets record for snowfall Buffalo in $1977$. Compared to the surrounding areas, there are higher temperatures and less snowfall in winter. The snowfall of $1977$ was quite moderate, but with a very strong wind, the speed of which was $70$ km per hour. At this point, there was already a layer of snow in the city. Not the strongest snow storm caused a terrible frost, zero visibility and a snowstorm. After the end of the snowfall in the city, the layer of snow that fell was $5$ meters - it was an absolute record season.

Dangerous phenomena of the summer period

For the summer period, there are dangerous natural phenomena associated with the atmosphere - these are heat, dry winds, droughts. They also include natural fires, floods, tornadoes, tornadoes, whirlwinds, etc.

Definition 2

Tornado- this is an ascending vortex of rapidly rotating air with particles of sand, dust, moisture

Over the sea such a whirlwind is called tornado, and over land - blood clots. In North America, blood clots are called tornado. This is an air funnel hanging from a cloud in the form of a trunk and falling to the ground. Tornadoes are formed in different parts of the planet and can be accompanied by thunderstorms and heavy showers. They can occur both over land and over water.

The birth of a tornado is associated with low cumulonimbus clouds, in the form of a dark funnel descending to the ground, but can also appear in clear weather. A tornado cloud occupies $5$-$10$ km across, sometimes even $15$ km. Its height is $4$-$5$ km, sometimes it can be $15$ km. There is usually a short distance between the surface of the earth and the base of the cloud. At the base of the mother cloud there is a collar cloud, the upper surface of which is located at a height of up to $1500$ m. The tornado itself hangs from the lower surface of the wall cloud lying under the collar cloud. Like a pump, a tornado sucks various objects into the cloud, which, falling into the vortex ring, are held in it and transported for tens of kilometers.

The main part of the tornado is funnel, which is a spiral vortex. The movement of air in the walls of the tornado goes in a spiral at a speed of about $ 200 $ m/s. Various objects, even people and animals caught in a tornado, rise up in the walls, and not along an empty internal cavity. Dense tornadoes have a small wall thickness compared to the width of the cavity. The air in the funnel can reach high speeds from $600-$1000 km/h. There are such whirlwinds of minutes, less often there are tens of minutes. One cloud can form entire groups of tornadoes. Tornadoes can travel from hundreds of meters to hundreds of kilometers. Their average speed is $50$-$60$ km/h. For them, the seas, lakes, forests, hills are not an obstacle. Having passed through the ground, a tornado can rise into the air without touching it and then descend again. The destructive power of the tornado is great - it tears up power supply and communication lines, disables equipment, destroys residential and industrial buildings, and leads to human casualties.

Within Russia, tornadoes are most often formed in the central regions, in the Volga region, in the Urals and Siberia. Tornadoes often form on the seas and, going out to the coast, increase their strength. It is almost impossible to predict the time and place of the appearance of a tornado; they arise mostly suddenly. Statistics speak of tornadoes near Arzamas, Murom, Kursk, Vyatka, Yaroslavl.

In Europe, these dangerous phenomena are rare, and they can be observed in hot summer weather. In the north, they were noted in southern Norway, Sweden, the Solovetsky Islands, in Siberia - up to the lower reaches of the Ob. Losses from these atmospheric phenomena amount to millions of dollars and, most importantly, human lives.

Rules of conduct for various atmospheric phenomena

Certain atmospheric phenomena cause damage not only to the economy, but also to the death of people. From this point of view, people should know the rules - how to behave in an unusual situation so as not to die.

Rules of conduct for snow drifts:

  1. With skid warning - restrict movement;
  2. Create a supply of food, water;
  3. Ropes are stretched between houses;
  4. In cars, close the blinds, cover the engine from the side of the radiator;
  5. You can not leave the car, so as not to lose the landmark;
  6. In rural areas, prepare food for animals;
  7. You can not be in dilapidated buildings, under power lines, under trees.

Of course, there is no special “recipe” for a tornado, but precautions will help in this situation.

Rules of conduct during a tornado:

  1. In private houses, it is necessary to check the fastening of the roof;
  2. Remove light objects from the open space - boxes, barrels;
  3. Close all windows and doors;
  4. Cut off the supply of water, gas and electricity;
  5. Go down to the basement.

Rules of conduct during a storm and thunderstorm:

  1. Disconnect electrical appliances from the power supply;
  2. Do not hold metal objects in your hands;
  3. Do not stand with them at an open window;
  4. Close windows and doors;
  5. Be in the center of the room;
  6. Stop the car in some lowland, if possible;
  7. Leave the car, do not run;
  8. You can not hide under trees, especially under larches and oaks;
  9. In the forest, the tent should stand in a low place;
  10. Wet things attract lightning;
  11. You can hide among low-growing trees;
  12. Clay soil increases the danger;
  13. You can not approach metal pipes and dilapidated buildings;

Thunderstorms often go against the wind. Before a thunderstorm, there is complete calm or the wind changes direction abruptly.

Dangerous atmospheric processes include: cyclones, tornadoes, heavy rains, snowfalls, etc. Countries located near ocean coasts often suffer from destructive cyclones. In the Western Hemisphere, cyclones are called hurricanes, and in the Pacific Northwest they are called typhoons.

The formation of cyclones is associated with intense heating (above 26-27°) of air above the ocean surface in comparison with its temperature over the continent. This leads to the formation of spiraling updrafts of air, bringing heavy rains and destruction to the coast.

The most destructive are tropical cyclones, which bring down on the coasts of the continents hurricane air currents at a speed of more than 350 km / h, heavy rainfall reaching 1000 mm for several days and storm waves up to 8 m high.

The conditions for the formation of tropical cyclones have been studied quite well. Seven areas of their origin have been identified in the World Ocean. All of them are located near the equator. Periodically, in these areas, the water warms up above the critical temperature (26.8°C), which leads to sharp atmospheric disturbances and the formation of a cyclone.

An average of 80 tropical cyclones occur annually around the globe. The coasts of the south of the Asian continent and the equatorial zone of North and South America (the Caribbean region) are the most vulnerable to them (Table 3). So, in Bangladesh over the past 30 years, more than 700 thousand people have died from cyclones. The most destructive cyclone took place in November 1970, when more than 300 thousand inhabitants of this country died and 3.6 million people were left homeless. Another cyclone in 1991 killed 140,000 people.

Japan experiences more than 30 cyclones annually. The strongest cyclone in the history of Japan (Ise-wan, 1953) killed more than 5,000 people, affected 39,000 people, destroyed about 150,000 residential buildings, washed away or buried under precipitation more than 30,000 hectares of arable land, caused 12 thousand damages on roads, there were about 7 thousand landslides. The total economic damage amounted to about 50 billion dollars.

In September 1991, the mighty typhoon Mirei swept over Japan, which killed 62 people and destroyed 700,000 houses. The total damage amounted to 5.2 billion dollars.

Very often, cyclones bring catastrophic downpours to the coast of Japan. One of these showers hit in 1979 on the flat part

The gaseous medium around the Earth, rotating with it, is called atmosphere. Its composition near the surface of the Earth: 78.1% nitrogen, 21% oxygen, 0.9% argon, in small fractions of a percent carbon dioxide, hydrogen, helium, and other gases. The lower 20 km contain water vapor. At an altitude of 20-25 km there is an ozone layer that protects living organisms on Earth from harmful short-wave (ionizing) radiation. Above 100 km, gas molecules decompose into atoms and ions, forming the ionosphere.

Atmospheric pressure is distributed unevenly, which leads to the movement of air relative to the Earth from high pressure to low pressure. This movement is called wind.

Beaufort wind strength near the ground (at a standard height of 10 m above an open flat surface)

Beaufort points

Verbal definition of wind strength

Wind speed, m/s

wind action

Calm. Smoke rises vertically

Mirror-smooth sea

The direction of the wind is noticeable by the drift of the smoke, but not by the weather vane

Ripples, no foam on the ridges

The movement of the wind is felt by the face, the leaves rustle, the weather vane is set in motion

Short waves, crests do not tip over and appear glassy

Leaves and thin branches of trees are constantly swaying, the wind is waving flags

Short, well defined waves. Combs, tipping over, form foam, occasionally small white lambs are formed

moderate

The wind raises dust and leaves, sets in motion the thin branches of trees

The waves are elongated, white lambs are visible in many places

Thin tree trunks sway, waves with crests appear on the water

Well developed in length, but not very large waves, white lambs are visible everywhere (splashes form in some cases)

strong

The thick branches of the trees sway, the wires of the overhead lines “buzz”

Large waves begin to form. White frothy ridges occupy large areas (splatter is likely)

Tree trunks sway, it's hard to go against the wind

Waves pile up, crests break, foam falls in stripes in the wind

Very strong

The wind breaks the branches of trees, it is very difficult to go against the wind

Moderately high long waves. On the edges of the ridges, spray begins to take off. Stripes of foam lie in rows in the direction of the wind

Minor damage; the wind begins to destroy the roofs of buildings

high waves. Foam in wide dense stripes lays down in the wind. The crests of the waves begin to capsize and crumble into spray that impair visibility.

Heavy storm

Significant destruction of buildings, trees uprooted. Rarely on land

Very high waves with long downward curved crests. The resulting foam is blown by the wind in large flakes in the form of thick white stripes. The surface of the sea is white with foam. The strong roar of the waves is like blows. Visibility is poor

Violent storm

Large destruction over a large area. Very rare on land

Exceptionally high waves. Small to medium sized boats are sometimes out of sight. The sea is all covered with long white flakes of foam, spreading downwind. The edges of the waves are everywhere blown into foam. Visibility is poor

32.7 and more

Huge destruction over a large area, trees uprooted, vegetation destroyed. Very rare on land

The air is filled with foam and spray. The sea is all covered with strips of foam. Very poor visibility

The area of ​​low pressure in the atmosphere with a minimum in the center is called cyclone. The weather during the cyclone is overcast, with strong winds.

Anticyclone is an area of ​​high pressure in the atmosphere with a maximum in the center. The anticyclone is characterized by cloudy, dry weather and light winds. The diameter of the cyclone and anticyclone reaches several thousand kilometers.

As a result of natural processes occurring in the atmosphere, phenomena are observed on Earth that pose an immediate danger or impede the functioning of human systems. Such atmospheric hazards include storms, hurricanes, tornadoes, fogs, black ice, lightning, hail, etc.

Storm. This is a very strong wind, causing great waves at sea and destruction on land. A storm can be observed during the passage of a cyclone or tornado. The wind speed at the earth's surface during a storm exceeds 20 m/s and can reach 50 m/s (with individual gusts up to 100 m/s). Short-term wind amplifications up to speeds of 20-30 m/s are called flurries. Depending on the points on the Beaufort scale, a severe storm at sea is called storm or typhoon, on the land - hurricane.

Hurricane. This is a cyclone, in which the pressure in the center is very low, and the winds reach a large and destructive force. Wind speed during a hurricane reaches 30 m/s or more.

Hurricanes are a maritime phenomenon and are most devastating near the coast (Figure 1). But hurricanes can penetrate far to land and are often accompanied by heavy rains, floods, storm surges, and in the open sea they form waves more than 10 m high. Tropical hurricanes are especially strong, the wind radius of which can exceed 300 km. The average duration of a hurricane is about 9 days, the maximum is 4 weeks.

The most terrible hurricane in the memory of mankind passed on November 12-13, 1970 over the islands in the Ganges Delta, Bangladesh. He claimed about a million lives. In the fall of 2005, Hurricane Katrina, which hit the United States, destroyed the dams protecting the city of New Orleans in a matter of hours, as a result of which the city of a million people was under water. According to official figures, more than 1,800 people died, more than one million people were evacuated.

Tornado. This is an atmospheric vortex that arises in a thundercloud and then propagates in the form of a dark sleeve towards the land or sea surface (Fig. 2). In the upper part, the tornado has a funnel-shaped extension that merges with the clouds. The height of the tornado can reach 800-1500 m. Inside the funnel, the air descends, and outside it rises, quickly rotating in a spiral, and an area of ​​​​very rarefied air is created. The rarefaction is so significant that closed objects filled with gas, including buildings, can explode from the inside due to the pressure difference. The rotation speed can reach 330 m/s. Usually the transverse diameter of the tornado funnel in the lower section is 300 - 400 m. When the funnel passes over land, it can reach 1.5 - 3 km, if the tornado touches the water surface, this value can be only 20 - 30 m.

The speed of tornadoes advance is different, on average 40-70 km/h, in rare cases it can reach 210 km/h. A tornado travels a path from 1 to 40 km long, sometimes more than 100 km, accompanied by a thunderstorm, rain, hail. Reaching the surface of the earth, it almost always produces great destruction, draws in water and objects encountered on its way, lifts them high up and transfers them for tens of kilometers. A tornado easily lifts objects weighing several hundred kilograms, sometimes several tons. In the USA they are called tornadoes, like hurricanes, tornadoes are identified from weather satellites.

Lightning- This is a giant electrical spark discharge in the atmosphere, usually manifested by a bright flash of light and the thunder that accompanies it. Lightning is divided into intracloud, that is, passing in the most thunderclouds, and ground, that is, hitting the ground. The process of ground lightning development consists of several stages.

At the first stage (in the zone where the electric field reaches a critical value), impact ionization begins, created by electrons, which, under the action of an electric field, move towards the earth and, colliding with air atoms, ionize them. Thus, electron avalanches arise, turning into threads of electrical discharges - streamers, which are well-conducting channels, which, when connected, give rise to steppedlightning leader. The movement of the leader to the earth's surface occurs in steps of several tens of meters. As the leader moves towards the ground, a response streamer is thrown out of the objects protruding on the surface of the earth, connecting with the leader. The creation of a lightning rod is based on this phenomenon.

The probability of a ground object being struck by lightning increases as its height increases and with an increase in the electrical conductivity of the soil. These circumstances are taken into account when installing a lightning rod.

Lightning can cause severe injury and death. A person is often struck by lightning in open spaces, since the electric current follows the shortest path "thundercloud - earth". Lightning strikes can be accompanied by destruction caused by its thermal and electrodynamic effects. Direct lightning strikes into overhead communication lines are very dangerous, as this can cause discharges from wires and equipment, which can lead to fires and electric shock to people. Direct lightning strikes on high-voltage power lines can cause short circuits. When lightning strikes a tree, people near it can be struck.