Dangerous atmospheric phenomena. kinds. Hazardous atmospheric phenomena (signs of approach, damaging factors, preventive actions and protection measures) Business card of a hazardous atmospheric phenomenon of your choice

Lesson number 18. Topic: Dangerous phenomena in the atmosphere. Lesson Objectives: the study of natural natural phenomena occurring in the atmosphere; development of the ability to analyze, draw conclusions, the ability to work in groups; education of activity, independence.

Tasks. To expand students' understanding of dangerous natural phenomena occurring in the atmosphere. Consider the causes of these phenomena. To introduce students to methods of dealing with dangerous phenomena in the atmosphere. Develop rules of conduct during the elements of the atmosphere.

Equipment. Physical map of the Voronezh region, atlases of the Voronezh region, workbooks, photographs of natural phenomena.

During the classes.

I. Organizing time.

II. Repetition. Checking homework.

a) On the board, the terms for repetition in groups: atmosphere, amplitude, atmospheric pressure, wind, weather, climate, pressure gauge, wind, how to calculate the average temperature.

b) Individual survey (by cards).

Card number 1.

1) Calculate the temperature amplitude for October (according to the calendar)

2) Build a daily temperature graph:

1h--1gr; 6h--4gr; 12h- +3gr; 19h-0gr.

Card number 2.

1) Calculate the temperature amplitude for January (according to the student's weather calendar).

2) Construct a graph of temperatures for the second week of October (according to the student's weather calendar).

III. Learning new material.

Remember what dangerous natural phenomena we have already met when studying the lithosphere and hydrosphere ( Earthquakes, volcanoes, floods ).

And today we will get acquainted with dangerous phenomena in the atmosphere. The earth's atmosphere forever affects the life and activities of people. We largely depend on its composition and the state of the surface layer-weather, on the processes and phenomena that accompany it. Some of them are used by humans for their own benefit as climatic resources. However, there are many among them that can cause significant damage. Give examples that match the scheme:

Now tell me, what dangerous phenomena do you know in the atmosphere? ( Drought, dry winds , dust storms, severe frosts, hail, ice, fog)

How do we structure our work? In front of you on the tables are tables that you need to fill out when you listen to the messages of your comrades. Fill in only the first two columns, in the third column I want to hear from you what methods of struggle you propose, and then we will fill it out.

Type of phenomenon	Features of manifestation	Methods of dealing with dangerous atmospheric phenomena
Drought	Long dry weather with high air temperature and lack of precipitation	Irrigation of fields, accumulation of moisture in the soil by snow retention, creation of ponds, breeding of drought-resistant varieties
Dust storm Suhovei	Strong continuous wind blowing upper layer soil.	Field-protective forest strips, non-moldboard plowing
frost	Air temperature drops below zero degrees in late spring and early autumn.	Smoke by burning combustible materials and creating fog curtains.
hail	The type of shower precipitation in the form of ice particles is predominantly round in shape.	Created a special anti-hail service
ice	A crust of ice that forms on the surface of the earth when the air temperature is below freezing. From drops of rain or fog. Formed in spring or autumn, maybe in winter.	In the fields, the ice crust is destroyed by machinery, roads are sprinkled with a special mixture.
Storm	Between the clouds and the earth's surface, electrical discharges occur - lightning, accompanied by thunder.	Lightning rods are used - metal rods.

We have listened to the messages of your comrades. Now let's talk about measures to combat them. The guys express their thoughts about the fight against these phenomena and fill in the third column of the table.

Conclusion: Dangerous natural phenomena endanger human life, Agriculture, operation of power transmission lines, industrial, civil structures, telephone network. In 2010 alone, the damage from droughts, frosts, hail, squally winds in the Voronezh region amounted to about 400 million rubles .

We have one more unresolved task left with you - this is the development of rules of conduct during natural disasters in the atmosphere.

1.City: a) If the hail caught you on the street, then try to choose a shelter. Otherwise, protect your head from hailstones;

b) Do not try to find shelter under the trees, as there is a great risk not only of being hit by lightning;

2.ice: Prepare non-slip shoes, attach metal heels or foam rubber to the heels, and stick adhesive tape or adhesive tape on dry soles, you can rub the soles with sand (sandpaper). Move carefully, slowly, stepping on the entire sole.

3. Heat: a) Wear light-colored, airtight clothing (preferably made of cotton) with a head covering;

b) In case of heat injury, immediately move to shade, wind or shower, drink plenty of water slowly. Try to cool your body down to avoid heat stroke;

4.Storm. If you are indoors, stay away from windows, electrical appliances, and pipes and other metal plumbing. Do not touch metal structures, wire fences or metal wire for drying clothes. Don't get close to them. Avoid holding long metal objects such as fishing rods, umbrellas, or golf clubs. Don't make phone calls. Before a thunderstorm, unplug external antennas and unplug radios and TVs. Disconnect modems and power supplies. Stay away from electrical appliances.

IV. Anchoring

Geographic dictation

1. Lowering the air temperature below zero degrees in spring and autumn ( frost ).

2. Precipitation in the form of ice particles (deg ).

3. A crust of ice formed when raindrops or fog freeze in spring or autumn (icy)

4. Accumulation of water droplets in the lower layer of the troposphere (fog).

5. Hot, dry, strong wind lasting several days dry wind).

6. Long period of dry weather with high air temperature ( drought).

V. Homework assignment. Learn notes in a notebook.

Leave your comment, thanks!

Federal Agency for Education Russian Federation

Far Eastern State Technical University

(DVPI named after V.V. Kuibyshev)

Institute of economics and management

by discipline: BZD

on the topic: Atmospheric hazards

Completed:

Student group U-2612

Vladivostok 2005

1. Phenomena occurring in the atmosphere

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

Its composition at the surface of the Earth: 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 earth's surface evaluated on the Beaufort scale.

Atmosphere 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, electric field atmospheres, electric charges of clouds, currents and discharges.

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 fogs, ice, lightning, hurricanes, storms, tornadoes, hail, snowstorms, tornadoes, showers, etc.

Ice - layer dense ice, formed on the surface of the earth and on objects (wires, structures) when supercooled drops of fog or rain freeze on them.

Ice is usually observed at air temperatures from 0 to -3°C, but sometimes even lower. The crust of frozen ice can reach a thickness of several centimeters. Under the influence of the weight of ice, structures can collapse, branches break off. Ice increases the danger to traffic and people.

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, intramass 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 has importance in safety.

hail - view 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.

Radiological methods have been developed to determine the hail and hail hazard of clouds, and operational hail control services have been created. The fight against hail is based on the principle of introduction with the help of rockets or. projectiles into a cloud of a reagent (usually lead iodide or silver iodide) that helps 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.

2. Zippers

Lightning is a giant electrical spark discharge in the atmosphere, usually manifested by a bright flash of light and accompanying thunder.

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 is divided into intra-cloud, i.e., passing in the thunderclouds themselves, and ground-based, i.e., striking 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, initially created by free electrons, always present in a small amount in the air, which, under the action of an electric field, acquire significant speeds towards the ground and, colliding with air atoms, ionize their. Thus, electron avalanches arise, turning into threads of electrical discharges - streamers, which are well-conducting channels, which, when connected, give rise to a bright thermally ionized channel with high conductivity - a step leader. The movement of the leader to the earth's surface occurs in steps of several tens of meters at a speed of 5 x 107 m/s, after which its movement stops for several tens of microseconds, and the glow is greatly weakened. In the subsequent stage, the leader again advances several tens of meters, while a bright glow covers all the steps passed. Then again the stop and weakening of the glow follows. These processes are repeated when the leader moves to the surface of the earth at an average speed of 2 x 105 m/sec. As the leader moves towards the ground, the field strength at its end increases and under its action 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. In the final stage, the leader-ionized channel is followed by a reverse, or main lightning discharge, characterized by currents from tens to hundreds of thousands of amperes, strong brightness and high speed advance 1O7..1O8 m/s. The temperature of the channel during the main discharge can exceed 25,000°C, the length of the lightning channel is 1-10 km, and the diameter is several centimeters. Such lightning is called protracted. They are the most common cause of fires. Lightning usually consists of several repeated discharges, the total duration of which can exceed 1 s. Intracloud lightning includes only leader stages, their length is from 1 to 150 km. 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. Unlike dangerous lightning, called linear, there are fireballs, which are often formed after a linear lightning strike. Lightning, both linear and ball, can cause severe injury and death. Lightning strikes can be accompanied by destruction caused by its thermal and electrodynamic effects. The greatest damage is caused by lightning strikes to ground objects in the absence of good conductive paths between the strike site and the ground. From electrical breakdown in the material, narrow channels are formed, in which a very heat, and part of the material evaporates with an explosion and subsequent ignition. Along with this, large potential differences between individual objects inside the building may occur, which can cause electric shock to people. Direct lightning strikes into overhead communication lines with wooden poles are very dangerous, as this can cause discharges from wires and equipment (telephone, switches) to the ground and other objects, which can lead to fires and electric shock to people. Direct lightning strikes on high-voltage power lines can cause short circuits. It is dangerous to get lightning into aircraft. When lightning strikes a tree, people near it can be struck.

3. Lightning protection

Discharges of atmospheric electricity can cause explosions, fires and destruction of buildings and structures, which led to the need to develop a special lightning protection system.

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

Its composition at the surface of the Earth: 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 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 radiation. Above 100 km, gas molecules decompose into atoms and ions, forming the ionosphere. Depending on the temperature distribution, the atmosphere is divided into 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. By definition, a cyclone is a closed area of atmospheric disturbance with low pressure in the center and vortex air movement. The area of low pressure in the atmosphere with a minimum in the center is called 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.

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 destructive effect of cyclones is determined by rainfall (snow) and high-speed wind pressure. According to building codes, the maximum standard value of wind pressure for the territory of Russia is 0.85 kPa, which, with a normal air density of 1.22 kg / m 3, corresponds to a wind speed of 37.3 m / s. However, as practice shows, not all structures can withstand winds of even lesser strength. The destructive force of blows from objects carried away by strong winds is also great.

In winter, blizzards occur during the passage of cyclones. According to the strength of the wind, blizzards are divided into five categories: weak, normal, strong, very strong and super strong. Depending on how the snow is carried by the wind, there are several types of blizzards: riding, low and general blizzards.

For people, strong blizzards pose a great danger at the moment when they are outside settlements in open areas.

The impact of the wind is unsafe, so it must be taken into account in Everyday life. So, in Kamchatka, when the wind speed is 30 m/s or more, by order of local authorities, schools, kindergartens and nurseries stop working, and when the wind is more than 35 m/s, women do not go to work. When designing structures, they provide that they can withstand the strongest winds. For the territory of Russia, the maximum value of wind speed in the design of buildings and structures is 37.3 m/s or 134 km/h, which corresponds to a wind force of 12 points.

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

Ice - a layer of dense ice that forms on the surface of the earth and on objects (wires, structures) when supercooled drops of fog or rain freeze on them. Ice is usually observed at air temperatures from 0 to -3°C, but sometimes even lower. The crust of frozen ice can reach a thickness of several centimeters. Under the influence of the weight of ice, structures can collapse, branches break off. Ice increases the danger to traffic and people.

Fog - accumulation of small water droplets or ice crystals, or both, in surface layer of the atmosphere(sometimes up to a height of several hundred meters), which reduces 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). Water droplet mist is observed mainly at air temperatures above -20°C. At temperatures below -20°C, ice fogs predominate. 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 cm 3 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.

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.

Thunderstorms. They are a fairly common and dangerous atmospheric phenomenon. Every year about 16 million thunderstorms pass all over the Earth and about 100 lightnings sparkle every second. Lightning discharge is extremely dangerous. It can cause destruction, fires and death.

It has been established that the average duration of one thunderstorm cycle is approximately 30 minutes, and the electric charge of each lightning flash corresponds to 20...30 C (sometimes up to 80 C). On flat terrain, the thunderstorm process includes the formation of lightning directed from the clouds to the ground. The charge moves down steps 50 ... 100 m long until it reaches the ground. When about 100 m remains to the earth's surface, lightning "aims" at some towering object.

Ball lightning is a kind of electrical phenomenon. It has the form of a luminous ball with a diameter of 20...30 cm, moving along an irregular trajectory and disappearing silently or with an explosion. Ball lightning exists for a few seconds, but can cause destruction and human casualties. In the Moscow region, for example, about 50 fires occur annually due to lightning discharges in the summer.

There are two types of lightning impact on objects: the impact of a direct lightning strike and the impact of secondary manifestations of lightning. A direct impact is accompanied by the release of a large amount of heat and causes the destruction of objects and the ignition of vapors of flammable liquids (flammable liquids), various combustible materials, as well as combustible structures of buildings and structures.

The secondary manifestation of lightning refers to phenomena that are accompanied by the manifestation of a potential difference on metal structures, pipes and wires inside buildings that have not been directly struck by lightning. High potentials induced by lightning create the risk of sparks between structures and equipment. In the presence of an explosive concentration of vapors, gases or dust of combustible substances, this leads to ignition or explosion.

Thunder - the sound in the atmosphere that accompanies a lightning bolt. Caused by air fluctuations under the influence of an instant increase in pressure in the path of lightning.

Lightning - it is a gigantic electrical spark discharge in the atmosphere, usually manifested by a bright flash of light and the thunder that accompanies it.

In the final stage, the leader-ionized channel is followed by a reverse, or main lightning discharge, characterized by currents from tens to hundreds of thousands of amperes, strong brightness and high speed of advancement. The temperature of the channel during the main discharge can exceed 25,000 0 C, the length of the lightning channel is 1-10 km, and the diameter is several centimeters. Such lightning is called protracted. They are the most common cause of fires. Lightning usually consists of several repeated discharges, the total duration of which can exceed 1 s.

Intracloud lightning includes only leader stages, their length is from 1 to 150 km. 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, both linear and ball, can cause severe injury and death. Lightning strikes can be accompanied by destruction caused by its thermal and electrodynamic effects. The greatest damage is caused by lightning strikes to ground objects in the absence of good conductive paths between the strike site and the ground. From electrical breakdown, narrow channels are formed in the material, in which a very high temperature is created, and part of the material evaporates with an explosion and subsequent ignition. Along with this, large potential differences between individual objects inside the building may occur, which can cause electric shock to people. Direct lightning strikes into overhead communication lines with wooden poles are very dangerous, as this can cause discharges from wires and equipment (telephone, switches) to the ground and other objects, which can lead to fires and electric shock to people. Direct lightning strikes on high-voltage power lines can cause short circuits. It is dangerous to get lightning into aircraft. When lightning strikes a tree, people near it can be struck.

The end of the century and the beginning of the century were associated with an increase in the number of hydrometeorological manifestations of natural disasters affecting people's livelihoods, which is largely due to the recorded warming on our planet. The number of extreme events of intense precipitation, floods, droughts and fires has increased by 2-4% over the past 50 years. tropical zone North Atlantic and Western North Pacific. Almost everywhere, the areas of mountain glaciers and ice masses are decreasing, a decrease in the area and thickness sea ice in the Arctic in spring and summer is consistent with a widespread increase in surface temperature. The increase in the concentration of greenhouse gases, natural and anthropogenic aerosols, the amount of clouds and precipitation, the strengthening of the role of El Niño manifestations cause a change in the global distribution of energy of the Earth-atmosphere system. The heat content of the world ocean has increased and the average sea level is rising at a rate of about 1-3 mm / year. Every year, tens of thousands of people become victims of hydrometeorological disasters, and material damage reaches tens of thousands of dollars.

Water is of great importance for life on Earth. It cannot be replaced by anything. She is needed by everyone and always. But water can also be the cause of big troubles. Of these, floods occupy a special place. According to the UN, over the past 10 years, 150 million people have suffered from floods worldwide. Statistics show that in terms of the area of distribution, the total average annual damage and the frequency of occurrence on a national scale, floods rank first among other natural disasters. As for human casualties and specific material damage, that is, damage per unit of affected area, in this respect, floods take second place after earthquakes.

Flooding is a significant flooding of the area caused by a rise in the water level in a river, lake, coastal region of the sea. For reasons that cause a rise in the water level, the following types of floods are distinguished: high water, high water, backwater, breakthrough flood, surge, under the action of an underwater source of high energy.

Floods and floods are associated with the passage of a large flow of water for a particular river.

A high water is a relatively long-term significant increase in the water content of a river that repeats annually in the same season. The reason for the flood is the increasing inflow of water into the river bed, caused by the spring melting of snow on the plains, the melting of snow and glaciers in the mountains in summer, and prolonged monsoon rains. The water level on small and medium lowland rivers during the spring flood rises by 2-5 meters, on large ones, for example, on Siberian rivers, by 10-20 meters. At the same time, rivers can overflow up to 10-30 km wide. and more. The largest known rise in water level up to 60 meters was observed in 1876. in China on the Yangtze River in the Yigan region. On small lowland rivers, the spring flood lasts 15-20 days, on large rivers - up to 2-3 months.

A flood is a relatively short-term (1-2 days) rise in water in a river caused by heavy rainfall or rapid melting of snow cover. Floods may recur several times a year. Sometimes they pass one after another, in waves, depending on the amount of heavy rain showers.

Backwater flooding occurs as a result of increased resistance to water flow during ice jams and ice jams at the beginning or end of winter, during traffic jams on timber-rafting rivers, with partial or complete blocking of the channel due to landslides during earthquakes, landslides.

Surge floods are created by wind surges of water in bays and bays on the sea coast and on the shores of large lakes. May occur in mouths major rivers due to backwater runoff surge wind wave. In our country, surge floods are observed in the Caspian and Seas of Azov, as well as in the mouths of the Neva, Western Dvina and Northern Dvina rivers. So in the city of St. Petersburg, such floods occur almost annually, especially large ones were in 1824. and in 1924

Flooding breakthrough is one of the most dangerous. It occurs when the destruction or damage of hydraulic structures (dams, dams) and the formation of a breakthrough wave. Destruction or damage to a structure is possible due to poor-quality construction, as a result of improper operation, the use of explosive weapons, as well as an earthquake.

Floods caused by the action of powerful impulsive sources in water basins also pose a serious danger. natural springs are underwater earthquakes and volcanic eruptions, as a result of these phenomena, tsunami waves form in the sea; technical sources - underwater nuclear explosions, in which surface gravitational waves are formed. When coming ashore, these waves not only flood the area, but also transform into a powerful hydro-flow, throwing ships ashore, destroying buildings, bridges, roads. For example, during the invasion and 1896. The tsunami washed away over 10,000 buildings on the northeastern coast of Honshu (Japan), killing about 26,000 people. Floods caused by the action of powerful impulsive sources in water basins also pose a serious danger. Natural sources are underwater earthquakes and volcanic eruptions, as a result of these phenomena, tsunami waves form in the sea; technical sources - underwater nuclear explosions, in which surface gravitational waves are formed. When coming ashore, these waves not only flood the area, but also transform into a powerful hydro-flow, throwing ships ashore, destroying buildings, bridges, roads. For example, during the invasion and 1896. The tsunami washed away over 10,000 buildings on the northeastern coast of Honshu (Japan), killing about 26,000 people.

The danger of flooding is that it can be unexpected, for example, during the passage of heavy rains at night. During a flood, there is a relatively short-term rise in water caused by heavy rains or rapid snowmelt.

In case of accidents accompanied by the destruction of the dam, the stored potential energy of the reservoir is released in the form of a breakthrough wave (such as a powerful flood), which is formed when water is poured out through a hole (gap) in the body of the dam. The breakthrough wave spreads along the river valley for hundreds of kilometers or more. The propagation of a breakthrough wave leads to flooding of the river valley downstream of the dam, as it was on the rivers North Caucasus in 2002. In addition, the breakthrough wave has a powerful damaging effect.

Surge floods, as a rule, are observed during the passage of powerful cyclones.

The cyclone is gigantic atmospheric vortex, A kind of cyclone - typhoon, translated from Chinese typhoon - a very strong wind, in America it is called a hurricane. It is an atmospheric vortex with a diameter of several hundred kilometers. The pressure at the center of a typhoon can reach 900 mbar. A strong decrease in pressure in the center and relatively small size lead to the formation of a significant pressure gradient in the radial direction. The wind in a typhoon reaches 3050 m/s, sometimes more than 50 m/s. Tangentially blowing winds usually surround a calm area called the eye of a typhoon. It has a diameter of 1525 km, sometimes up to 5060 km. A cloudy wall is formed along its border, resembling the wall of a vertical circular well. Especially high surge floods are associated with typhoons. When a cyclone passes through the sea, the water level in its central part rises.

Mudflows are mud or mud-stone streams that suddenly arise in the channels of mountain rivers with large slopes of the bottom as a result of intense and prolonged showers, rapid melting of glaciers and snow cover, as well as the collapse of large amounts of loose clastic materials into the channel. According to the composition of mudflows, mudflows are distinguished: mud, mud-stone, water-stone, and according to physical properties- unconnected and connected. In non-cohesive mudflows, the transport medium for solid inclusions is water, and in cohesive mudflows, it is a water-ground mixture in which the bulk of water is bound by fine particles. The content of solid material (products of destruction of rocks) in the mudflow can be from 10% to 75%.

Unlike ordinary water flows, mudflows usually move not continuously, but in separate waves (waves), which is due to their formation mechanism and the jamming nature of the movement - the formation of accumulations of solid material in the narrowings and bends of the channel with their subsequent breakthrough. Mudflows move at speeds up to 10 m/s or more. The thickness (height) of a mudflow can reach up to 30 m. The volume of removals is hundreds of thousands, sometimes millions of m 3, and the size of the carried debris is up to 3-4 m in diameter with a mass of up to 100-200 tons.

Possessing large mass and speed of movement, mudflows destroy industrial and residential buildings, engineering structures, roads, power lines and communications.

Lightning is a giant electrical spark discharge in the atmosphere, usually manifested by a bright flash of light and accompanying thunder. 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.

At the first stage, in the zone where the electric field reaches a critical value, impact ionization begins, initially created by free electrons, always present in a small amount in the air, which, under the action of an electric field, acquire significant speeds towards the ground and, colliding with air atoms, ionize their. Thus, electron avalanches arise, turning into threads of electrical discharges - streamers, which are well-conducting channels, which, when connected, give rise to a bright thermally ionized channel with high conductivity - a step leader. The movement of the leader to the earth's surface occurs in steps of several tens of meters at a speed of 5 x 107 m/s, after which its movement stops for several tens of microseconds, and the glow is greatly weakened. In the subsequent stage, the leader again advances several tens of meters, while a bright glow covers all the steps passed. Then again the stop and weakening of the glow follows. These processes are repeated when the leader moves to the surface of the earth at an average speed of 2 x 105 m/sec. As the leader moves towards the ground, the field strength at its end increases and under its action 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. In the final stage, the leader-ionized channel is followed by a reverse, or main lightning discharge, characterized by currents from tens to hundreds of thousands of amperes, strong brightness and a high advance velocity of 107..108 m/s. The temperature of the channel during the main discharge can exceed 25,000°C, the length of the lightning channel is 1-10 km, and the diameter is several centimeters. Such lightning is called protracted. They are the most common cause of fires. Lightning usually consists of several repeated discharges, the total duration of which can exceed 1 s. Intracloud lightning includes only leader stages, their length is from 1 to 150 km. 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. Unlike dangerous lightning, called linear lightning, there are ball lightning, which are often formed after a linear lightning strike. Lightning, both linear and ball, can cause severe injury and death. Lightning strikes can be accompanied by destruction caused by its thermal and electrodynamic effects. The greatest damage is caused by lightning strikes to ground objects in the absence of good conductive paths between the strike site and the ground. From electrical breakdown, narrow channels are formed in the material, in which a very high temperature is created, and part of the material evaporates with an explosion and subsequent ignition. Along with this, large potential differences between individual objects inside the building may occur, which can cause electric shock to people. Direct lightning strikes into overhead communication lines with wooden poles are very dangerous, as this can cause discharges from wires and equipment (telephone, switches) to the ground and other objects, which can lead to fires and electric shock to people. Direct lightning strikes on high-voltage power lines can cause short circuits. It is dangerous to get lightning into aircraft. When lightning strikes a tree, people near it can be struck.

Also, atmospheric hazards include fogs, ice, lightning, hurricanes, storms, tornadoes, hail, snowstorms, tornadoes, showers, etc.

Ice is a layer of dense ice that forms on the surface of the earth and on objects (wires, structures) when supercooled drops of fog or rain freeze on them.

Fog is an accumulation of small water droplets or ice crystals, or both, in the surface layer of the atmosphere (sometimes 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 varies 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.

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.

Hail is a type of 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.

A tornado is an atmospheric vortex that arises in a thundercloud and then spreads in the form of a dark sleeve or trunk towards the land or sea surface (Fig. 23).

In the upper part, the tornado has a funnel-shaped extension that merges with the clouds. When a tornado descends to the earth's surface, its lower part also sometimes becomes expanded, resembling an overturned funnel. The height of the tornado can reach 800-1500 m. The air in the tornado rotates and simultaneously rises in a spiral upward, drawing dust or hearth. The rotation speed can reach 330 m/s. Due to the fact that inside the vortex the pressure decreases, the water vapor condenses. In the presence of dust and water, the tornado becomes visible.

The diameter of a tornado over the sea is measured in tens of meters, over land - hundreds of meters.

A tornado usually occurs in the warm sector of a cyclone and moves instead of<* циклоном со скоростью 10-20 м/с.

A tornado travels a path from 1 to 40-60 km long. A tornado is accompanied by a thunderstorm, rain, hail and, if it reaches the surface of the earth, it almost always causes great destruction, sucks in water and objects that are on its way, lifts them high up and carries them over long distances. Objects weighing several hundred kilograms are easily lifted by a tornado and carried over tens of kilometers. A tornado at sea is a danger to ships.

Tornadoes over land are called blood clots, in the US they are called tornadoes.

Like hurricanes, tornadoes are identified by weather satellites.

The science

The earth's atmosphere is a source of amazing and amazing phenomena. In ancient times, atmospheric phenomena were considered a manifestation of God's will, today someone takes them for alien aliens. Nowadays, scientists have revealed many secrets of nature, including optical phenomena.

In this article we will tell you about amazing natural phenomena, some of them are very beautiful, others are deadly, but they are all an integral part of our planet.

atmospheric phenomena

The lunar rainbow, also known as the night rainbow, is a phenomenon generated by the moon. Always located on the opposite side of the sky from the moon. For a lunar rainbow to appear, the sky must be dark and rain must fall on the opposite side of the moon (except for those rainbows caused by a waterfall). Best of all, such a rainbow is seen when the phase of the moon is close to the full moon. The lunar rainbow is paler and thinner than the usual solar one. But this is also a rarer occurrence.

Bishop's Ring is a brown-red circle around the Sun that occurs during and after volcanic eruptions. Light is refracted by volcanic gases and dust. The sky inside the ring becomes light with a blue tint. This atmospheric phenomenon was discovered by Edward Bishop in 1883, after the famous eruption of the Krakatoa volcano.

Halo is an optical phenomenon, a glowing ring around a light source, usually the Sun and Moon. There are many types of halo and they are caused mainly by ice crystals in cirrus clouds at an altitude of 5-10 km in the upper atmosphere. Sometimes the light is refracted through them so strangely that the so-called false suns appear, in ancient times, considered a bad omen.

The belt of Venus is an atmospheric optical phenomenon. Appears as a strip of pink to orange between the dark night sky below and the blue above. Appears before sunrise or after sunset and runs parallel to the horizon on the opposite side of the Sun.

Noctilucent clouds are the highest clouds in the atmosphere and a rare natural phenomenon. They are formed at an altitude of 70-95 km. Noctilucent clouds can only be seen during the summer months. In the northern hemisphere in June-July, in the southern hemisphere in late December - early January. The time for the appearance of such clouds is evening and evening twilight.

Aurora borealis, aurora borealis (Aurora Borealis) - the sudden appearance of colored lights in the night sky, usually green. Caused by the interaction of charged particles arriving from space and interacting with atoms and molecules of air in the upper layers of the earth's atmosphere. The aurora is observed mainly in the high latitudes of both hemispheres in oval zones - belts surrounding the Earth's magnetic belts.

The moon itself does not emit light. What we see is only the reflection of the sun's rays from its surface. Due to changes in the composition of the atmosphere, the moon changes its usual color to red, orange, green or blue. The rarest color of the moon is blue. It is usually caused by ash in the atmosphere.

Mammatus clouds are one of the varieties of cumulus clouds that have a cellular structure. They are rare, mainly in tropical latitudes, and are associated with the formation of tropical cyclones. Mammatus are located under the main cluster of powerful cumulus clouds. Their color is usually gray-blue, but due to the direct rays of the Sun or the illumination of other clouds, they may appear golden or reddish.

A fiery rainbow is one of the types of halo, which is the appearance of a horizontal rainbow against the background of light, high clouds. This rare weather phenomenon occurs when light passes through cirrus clouds and refracts through flat ice crystals. The rays enter through the vertical side wall of the hexagonal crystal, exiting from the lower horizontal side. The rarity of the phenomenon is explained by the fact that the ice crystals in the cloud must be oriented horizontally in order to refract the sun's rays.

Diamond dust is solid precipitation in the form of tiny ice crystals floating in the air, formed in frosty weather. Diamond dust usually forms under clear or near clear skies and resembles fog. However, unlike fog, it does not consist of water droplets, but of ice crystals and in rare cases slightly reduces visibility. Most often this phenomenon can be observed in the Arctic and Antarctic, but can be anywhere at an air temperature of -10, -15.

Zodiacal light - a faint glow of the sky, visible in the tropics at any time of the year, extending along the ecliptic, i.e. in the realm of the zodiac. This is the result of the scattering of sunlight in dust accumulations in the region of the Earth's rotation around the Sun. It can be observed either in the evening over the western part of the horizon, or in the morning over the eastern. It has the form of a cone, narrowing with distance from the horizon, gradually losing its brightness and turning into the zodiacal band.

Sometimes during sunset or sunrise, you can see a vertical band of light stretching from the sun. Solar pillars are formed as a result of the reflection of sunlight from flat ice crystals in the Earth's atmosphere. Usually pillars are formed due to the sun, but the moon and artificial light sources can become a source of light.

Dangerous natural phenomena

A fire tornado or tornado is a rare natural phenomenon. For its formation, several large fires are needed, as well as strong winds. Further, these several fires are combined and a huge fire is obtained. The speed of rotation of the air inside the tornado is over 400 km / h, and the temperature reaches 1000 degrees Celsius. The main danger of such a fire is that it will not stop until it burns everything in its path.

A mirage is a natural phenomenon, as a result of which imaginary images of various objects appear. This happens due to the refraction of light streams at the boundary between layers of air that are sharply different in density and temperature. Mirages are divided into upper - visible above the object, lower - visible under the object, and side.

A rare complex optical phenomenon, consisting of several forms of mirages, in which distant objects are seen repeatedly and with various distortions, is called Fata Morgana. Often the victims of mirages are travelers in the El-er-Rawi desert. In front of people, in the vicinity, oases appear, which are actually 700 km away.