Lesson number 18. Subject: 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 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 man for his 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.

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: Hazardous natural phenomena pose a threat to human life, agriculture, the operation of power lines, industrial and civil structures, and the 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

Geographical 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.

Hazardous atmospheric phenomena (signs of approach, damaging factors, preventive measures and protective measures)

Meteorological and agrometeorological hazards

Meteorological and agrometeorological hazards are divided into:

storms (9-11 points):

hurricanes (12-15 points):

tornadoes, tornadoes;

vertical vortices;

large hail;

heavy rain (rainstorm);

heavy snowfall;

heavy ice;

severe frost;

strong blizzard;

heatwave;

heavy fog;

frosts.

Fog is the concentration of small drops of water or ice crystals in the surface layer of the atmosphere from air saturated with water vapor when it cools. In fog, horizontal visibility decreases to 100 m or less. Depending on the horizontal visibility range, heavy fog (visibility up to 50 m), moderate fog (visibility less than 500 m) and light fog (visibility from 500 to 1000 m) are distinguished.

Weak clouding of the air with horizontal visibility from 1 to 10 km is called a veil. The veil can be strong (visibility 1-2 km), moderate (up to 4 km) and weak (up to 10 km). Fogs are distinguished by origin: advective and radiation. The deterioration in visibility complicates the work of transport - flights are interrupted, the schedule and speed of ground transport change. Drops of fog, settling on the surface or ground objects under the influence of gravity or air flow, moisten them. There have been repeated cases of overlapping of insulators of high-voltage power lines as a result of deposition of fog and dew drops on them. Fog drops, like dew drops, are a source of additional moisture for field plants. Settling on them, the drops maintain a high relative humidity around them. On the other hand, drops of fog, settling on plants, contribute to the development of decay.

At night, fogs protect vegetation from excessive cooling as a result of radiation, weaken the harmful effects of frost. During the day, fogs protect the vegetation from solar overheating. Settling of mist drops on the surface of machine parts leads to damage to their coatings and corrosion.

According to the number of days with fog, Russia can be divided into three parts: mountainous areas, the central elevated part and low-lying areas. The frequency of fog increases from south to north. Some increase in the number of days with fog is observed in spring. Fogs of all types can be observed both at negative and at positive temperatures of the soil surface (from 0 to 5°C).

Black ice is an atmospheric phenomenon that is formed as a result of freezing of drops of supercooled rain or fog on the surface of the earth and objects. Is a formation dense ice, transparent or opaque, which grows on the windward side.

The most significant black ice is observed during the passage of southern cyclones. When cyclones move eastward from the Mediterranean Sea and fill them over the Black Sea, icy patches are observed in southern Russia.

The duration of sleet is different - from parts of an hour to 24 hours or more. Educated icing keeps on objects for a long time. As a rule, black ice forms at night at negative air temperatures (from 0° to - 3°С). Black ice, together with strong winds, causes significant damage to the economy: wires are torn under the weight of icing, telegraph poles fall, trees die, traffic stops, etc.

Hoarfrost is an atmospheric phenomenon, which is the deposition of ice on thin long objects (tree branches, wires). There are two types of frost - crystalline and granular. The conditions for their formation are different. Crystalline frost is formed during fog as a result of sublimation (the formation of ice crystals immediately from water vapor without its transition to a liquid state or upon rapid cooling below 0 ° C) of water vapor, consists of ice crystals. Their growth occurs on the windward side of objects in light winds and temperatures below -15°C. The length of the crystals, as a rule, does not exceed 1 cm, but can reach several centimeters. Granular hoarfrost - snow-like loose ice that grows on objects in foggy, mostly windy weather.

It has sufficient strength. The thickness of this frost can reach many centimeters. Most often, crystalline hoarfrost occurs in the central part of the anticyclone with high relative humidity below the inversion layer. Grainy hoarfrost, according to the conditions of formation, is close to sleet. Rime frost is observed throughout Russia, but is distributed unevenly, since its formation is influenced by local conditions - the height of the terrain, the shape of the relief, the exposure of slopes, protection from the prevailing moisture-bearing flow, etc.

Due to the low density of hoarfrost (bulk density from 0.01 to 0.4), the latter to a greater extent only causes increased vibration and sagging of power transmission and communication wires, but can also cause them to break. Hoarfrost poses the greatest danger to communication lines during strong winds, as the wind creates an additional load on the wires, which sag under the weight of deposits, and the risk of their breakage increases.

A snowstorm is an atmospheric phenomenon, which is the transfer of snow by the wind over the surface of the earth with a deterioration in visibility. There are such blizzards as a blowing snow, when most of the snowflakes rise a few centimeters above the snow cover; blowing blizzard if snowflakes rise to 2 m or more. These two types of blizzards occur without snow falling from the clouds. And, in the end, a general, or upper, blizzard - snowfall with a strong wind. Blizzards reduce visibility on the roads, interfere with the operation of transport.

A thunderstorm is a complex atmospheric phenomenon in which electrical discharges (lightning) occur in large rain clouds and between clouds and the ground, which are accompanied by a sound phenomenon - thunder, winds and heavy rainfall, often hail. Lightning strikes damage ground objects, power lines and communications. Squalls and downpours, floods and hail accompanying a thunderstorm cause damage to agriculture and some areas of industry. Distinguish between intramass thunderstorms and thunderstorms that occur in zones atmospheric fronts. Intra-mass thunderstorms, as a rule, are short-term and occupy a smaller area than frontal ones. They arise as a result of strong heating of the underlying surface. Thunderstorms in the atmospheric front zone are distinguished by the fact that they often occur in the form of chains of thunderstorm cells that move parallel to each other, covering a large area.

They occur on cold fronts, fronts of occlusion, as well as on warm fronts in warm, humid, usually tropical air. The zone of frontal thunderstorms has a width of tens of kilometers with a front length of hundreds of kilometers. Approximately 74% of thunderstorms are observed in the front zone, other thunderstorms are intramass.

During a thunderstorm:

in the forest to hide among low trees with dense crowns;

in the mountains and in open areas to hide in a pit, ditch or ravine;

fold all large metal objects 15-20 meters away from you;

having sheltered from a thunderstorm, sit down, bending your legs under you and lowering your head on your legs bent at the knees, connect your feet together;

put under yourself, a plastic bag, branches or spruce branches, stones, clothes, etc. isolating from the soil;

on the way, the group disperse, go one at a time, slowly;

in shelter, change into dry clothes, in extreme cases, carefully squeeze out wet ones.

During a thunderstorm, do not:

take cover near lone trees or trees protruding above others;

lean or touch rocks and sheer walls;

stop at the edges of the forest, large clearings;

walk or stop near bodies of water and in places where water flows;

hide under rocky canopies;

run, fuss, move in a tight group;

be in wet clothes and shoes;

stay on high ground;

be near watercourses, in crevices and cracks.

blizzard

A snow storm is one of the varieties of a hurricane, characterized by significant wind speeds, which contributes to the movement of huge masses of snow through the air, and has a relatively narrow band of action (up to several tens of kilometers). During a storm, visibility deteriorates sharply, and transport communication, both intracity and intercity, may be interrupted. The duration of the storm varies from several hours to several days.

Blizzard, blizzard, blizzard are accompanied by sharp temperature changes and snowfall with strong gusts of wind. The temperature difference, snowfall with rain at low temperatures and strong winds, creates conditions for icing. Power lines, communication lines, roofs of buildings, various supports and structures, roads and bridges are covered with ice or sleet, which often causes their destruction. Ice formations on the roads make it difficult, and sometimes completely hinder the operation of road transport. Pedestrian movement will be difficult.

Snowdrifts occur as a result of heavy snowfalls and snowstorms, which can last from several hours to several days. They cause disruption of transport communication, damage to communication lines and power lines, negatively affect economic activity. Snow drifts are especially dangerous when snow avalanches come down from the mountains.

The main damaging factor of such natural disasters is the impact of low temperature on the human body, causing frostbite, and sometimes freezing.

In the event of an immediate threat, the population is alerted, the necessary forces and means, road and utility services are put on alert.

A snowstorm, blizzard or blizzard can last for several days, so it is recommended to create a supply of food, water, fuel in the house in advance, and prepare emergency lighting. You can leave the premises only in exceptional cases and not alone. Restrict movement, especially in rural areas.

Vehicles should only be used on main roads. In the event of a sharp increase in wind, it is advisable to wait out the bad weather in the village or near it. If the machine breaks down, do not leave it out of sight. If it is impossible to move further, mark the parking lot, stop (with the engine to the windward side), cover the engine from the side of the radiator. In case of heavy snowfall, make sure that the car is not covered with snow, i.e. shovel snow as needed. The car engine must be periodically warmed up to avoid its “defrosting”, while preventing exhaust gases from entering the cab (body, interior), for this purpose, make sure that the exhaust pipe is not blocked with snow. If there are several cars, it is best to use one car as a shelter, the engines of other cars must be drained of water.

In no case should you leave the shelter (car), in heavy snow, landmarks after a few tens of meters can be lost.

A snowstorm, snowstorm or blizzard can be waited out in a shelter equipped with snow. Shelter is recommended to be built only in open areas, where snow drifts are excluded. Before you take cover, you need to find landmarks on the ground in the direction of the nearest housing and remember their location.

Periodically, it is necessary to control the thickness of the snow cover by piercing the ceiling of the shelter, and to clear the entrance and the ventilation hole.

It is possible to find an elevated, steadily standing object in an open and snowless area, take cover behind it and constantly discard and trample down the arriving snow mass with your feet.

IN critical situations it is permissible to completely bury yourself in dry snow, for which you put on all warm clothes, sit with your back to the wind, cover yourself with plastic wrap or a sleeping bag, pick up a long stick and let the snow sweep you. Constantly clear the ventilation hole with a stick and expand the volume of the formed snow capsule in order to be able to get out of the snow drift. Inside the resulting shelter, a landmark arrow should be laid out.

Remember that a blizzard due to multi-meter snow drifts and snowdrifts can significantly change appearance terrain.

The main types of work during snow drifts, snowstorms, snowstorms or blizzards are:

search for missing people and providing them with first aid, if necessary;

clearing roads and areas around buildings;

providing technical assistance to stuck drivers;

elimination of accidents on utility and energy networks.

Hail is an atmospheric phenomenon associated with the passage of cold fronts. Occurs with strong ascending air currents during the warm seasons. Droplets of water, falling to a great height with air currents, freeze, and ice crystals begin to grow on them in layers. Drops become heavier and begin to fall down. When falling, they increase in size from merging with drops of supercooled water. Sometimes the hail can reach the size chicken egg. As a rule, hail falls from large rain clouds during a thunderstorm or a downpour. It can cover the ground with a layer of up to 20-30 cm. The number of days with hail increases in mountainous areas, on hills, in areas with rugged terrain. Hail falls mainly in the second half of the day in relatively small areas of several kilometers. Hail usually lasts from several minutes to a quarter of an hour. The hail causes significant material damage. It destroys crops, vineyards, knocks flowers and fruits from plants. If the size of the hailstones is significant, it can cause the destruction of buildings and death of people. At present, methods have been developed for determining hail clouds, and a hail control service has been created. Dangerous clouds are "shot" with special chemicals.

Dry wind - hot and dry wind with a speed of 3 m/s or more, with high air temperature up to 25°C and low relative humidity up to 30%. Dry winds are observed in partly cloudy weather. Most often they occur in the steppes along the periphery of anticyclones that form over the North Caucasus and Kazakhstan.

The highest dry wind speeds were observed during the day, the lowest - at night. Dry winds cause great damage to agriculture: they raise the water balance of plants, especially when there is a lack of moisture in the soil, since intensive evaporation cannot be compensated by the influx of moisture through root system. With prolonged action of dry winds, the ground part of the plants turns yellow, the foliage curls, their wilting occurs and even the death of field crops.

Dust, or black, storms are the transfer of large amounts of dust or sand by strong winds. They occur during dry weather due to the winding of sprayed soil over great distances. The occurrence, frequency, and intensity of dust storms are greatly influenced by orography, the nature of soils, forest cover, and other terrain features.

Most often, dust storms occur from March to September. The most intense and dangerous spring dust storms are during a prolonged absence of rain, when the soil dries out, and the plants are still underdeveloped and do not form a continuous cover. At this time, storms blow out the soil over vast areas. Reduced horizontal visibility. S.G. Popruzhenko researched dust storm in 1892 in the south of Ukraine. Here is how he described it: “A dry, strong east wind tore the ground for several days and drove masses of sand and dust. The crops, which turned yellow from dry air, were cut under the root, like a sickle, but the roots could not survive. The earth was demolished up to 17 cm deep.Canals filled up to 1.5 m.

Hurricane

A hurricane is a wind of destructive force and considerable duration. A hurricane occurs suddenly in areas with a sharp drop in atmospheric pressure. The speed of a hurricane reaches 30 m/s or more. In terms of its harmful effects, a hurricane can be compared with an earthquake. This is explained by the fact that hurricanes carry colossal energy, its amount released by an average hurricane in one hour can be compared with the energy of a nuclear explosion.

A hurricane can capture an area up to several hundred kilometers in diameter and is capable of moving thousands of kilometers. At the same time, the hurricane wind destroys strong and demolishes light buildings, devastates sown fields, breaks wires and knocks down power transmission and communication poles, damages highways and bridges, breaks and uproots trees, damages and sinks ships, causes accidents on utility and energy networks . There were times when hurricane winds threw trains off the rails and knocked down factory chimneys. Often hurricanes are accompanied by heavy rains that cause flooding.

A storm is a type of hurricane. The wind speed during a storm is not much less than the speed of a hurricane (up to 25-30 m/s). Losses and destruction from storms are significantly less than from hurricanes. Sometimes a strong storm is called a storm.

A tornado is a strong small-scale atmospheric vortex with a diameter of up to 1000 m, in which the air rotates at a speed of up to 100 m / s, which has great destructive power (in the USA it is called a tornado).

On the territory of Russia, tornadoes are observed in Central region, Volga, Urals, Siberia, Transbaikalia, Caucasian coast.

A tornado is an ascending vortex consisting of extremely rapidly rotating air mixed with particles and moisture, sand, dust and other suspensions. On the ground, he moves in the form of a dark column of spinning air with a diameter of several tens to several hundred meters.

In the internal cavity of the tornado, the pressure is always reduced, so any objects that are in its path are sucked into it. The average speed of the tornado is 50-60 km / h, when it approaches, a deafening rumble is heard.

Strong tornadoes travel tens of kilometers and tear off roofs, uproot trees, lift cars into the air, scatter telegraph poles, and destroy houses. Threat notification is carried out by giving a signal "Attention to all" by a siren and subsequent voice information.

Actions upon receipt of information about an impending hurricane, storm or tornado - you should carefully listen to the instructions of the civil defense authority, which will report the estimated time, strength of the hurricane and recommendations on the rules of conduct.

Upon receipt of a storm warning, it is necessary to immediately begin to carry out preventive work:

reinforce insufficiently strong structures, close doors, dormer openings and attic spaces, sheathe windows with boards or close them with shields, and glue the glass with strips of paper or cloth, or, if possible, remove it;

in order to balance the external and internal pressure in the building, it is advisable to open the doors and windows on the leeward side and fix them in this position;

from roofs, balconies, loggias and window sills it is necessary to remove things that, if they fall, can cause injury to people. Items located in the yards must be secured or brought into the premises;

it is also advisable to take care of emergency lamps - electric lamps, kerosene lamps, candles. It is also recommended to create stocks of water, food and medicines, especially dressings;

put out the fire in the stoves, check the condition of electrical switches, gas and water taps;

take pre-prepared places in buildings and shelters (in case of tornadoes - only in basements and underground structures). Indoors, you need to choose the safest place - in the middle part of the house, in the corridors, on the first floor. To protect against injury from glass fragments, it is recommended to use built-in wardrobes, durable furniture and mattresses.

The safest places during a storm, hurricane or tornado are shelters, basements and cellars.

If a hurricane or tornado caught you in an open area, it is best to find any natural recess in the ground (ditch, pit, ravine or any recess), lie down on the bottom of the recess and press firmly against the ground. Leave the transport (regardless of whichever one you are in) and take cover in the nearest basement, shelter or recess. Take measures to protect against heavy rainfall and large hail, as hurricanes are often accompanied by them.

be on bridges, as well as in close proximity to objects that use poisonous, potent and flammable substances in their production;

take cover under separate trees, poles, come close to power line supports;

be near buildings from which gusts of wind blow away tiles, slates and other objects;

After receiving a message about the stabilization of the situation, you should leave the house carefully, you need to look around for hanging objects and parts of structures, broken electrical wires. it is possible that they are under voltage.

Without extreme necessity, do not enter damaged buildings, but if such a need arose, then this should be done carefully, making sure that there are no significant damage to stairs, ceilings and walls, fires, breaks in electrical wires, and elevators should not be used.

The fire should not be lit until there is confidence that there was no gas leak. When outdoors, stay away from buildings, poles, high fences, etc.

The main thing in these conditions is not to panic, to act competently, confidently and reasonably, to prevent oneself and keep others from unreasonable acts, to provide assistance to the victims.

The main types of damage to people during hurricanes, storms and tornadoes are closed injuries. various areas bodies, bruises, fractures, concussions, wounds accompanied by bleeding.

Federal Agency for Education of the 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 at the earth's surface is estimated 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, the electric field of the atmosphere, 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.

Icing 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.

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, 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 are formed due to the cooling of warm humid air when it moves over a colder surface of 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.

Hail - 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.

Radiological methods have been developed for determining 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 electric 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 from average speed 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 injuries and death of people. 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 may occur between individual objects inside the building, which can cause injury to people. electric shock. 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.

Lightning protection is a complex of protective devices designed to ensure the safety of people, the safety of buildings and structures, equipment and materials from lightning discharges.

Lightning is capable of influencing buildings and structures with direct strikes (primary impact), which cause direct damage and destruction, and secondary impacts - through the phenomena of electrostatic and electromagnetic induction. The high potential created by lightning discharges can also be brought into buildings through overhead lines and various communications. The channel of the main lightning discharge has a temperature of 20,000°C and higher, causing fires and explosions in buildings and structures.

Buildings and structures are subject to lightning protection in accordance with SN 305-77. The choice of protection depends on the purpose of the building or structure, the intensity of lightning activity in the area under consideration and the expected number of lightning strikes of the object per year.

The intensity of thunderstorm activity is characterized by the average number of thunderstorm hours per year pm or the number of thunderstorm days per year pm. It is determined using the appropriate map given in CH 305-77 for a particular area.

A more generalized indicator is also used - the average number of lightning strikes per year (p) per 1 km2 of the earth's surface, which depends on the intensity of thunderstorm activity.

Table 19. Intensity of thunderstorm activity

The expected number of lightning strikes per year of buildings and structures N, not equipped with lightning protection, is determined by the formula:

N \u003d (S + 6hx) (L + 6hx) n 10 "6,

where S and L are, respectively, the width and length of the protected building (structure), which has a rectangular shape in plan, m; for buildings of complex configuration, when calculating N as S and L, they take the width and length of the smallest rectangle into which the building can be inscribed in the plan; hx - the highest height of the building (structure), m; n. - the average annual number of lightning strikes per 1 km2 of the earth's surface at the location of the building. For chimneys, water towers, masts, trees, the expected number of lightning strikes per year is determined by the formula:

In a power transmission line unprotected from lightning with a length of L km with an average height of suspension of wires hcp, the number of lightning strikes per year will be, assuming that the danger zone extends from the axis of the line in both directions by 3 hcp,

N \u003d 0.42 x K) "3 xLhcpnh

Depending on the probability of a fire or explosion caused by lightning, based on the extent of possible destruction or damage, the standards establish three categories of lightning protection devices.

Explosive mixtures of gases, vapors and dust are stored for a long time and systematically occur in buildings and structures classified as lightning protection category I, explosives are processed or stored. Explosions in such buildings, as a rule, are accompanied by significant destruction and loss of life.

In buildings and structures of category II lightning protection, these explosive mixtures can occur only at the time of an industrial accident or a malfunction of technological equipment; explosives are stored in reliable packaging. Lightning strikes into such buildings, as a rule, are accompanied by much less destruction and casualties.

In buildings and structures of category III, a direct lightning strike can cause a fire, mechanical damage and injury to people. This category includes public buildings, chimneys, water towers, etc.

Buildings and structures classified as category I according to the lightning protection device must be protected from direct lightning strikes, electrostatic and electromagnetic induction and the introduction of high potentials through ground and underground metal communications throughout Russia.

Buildings and structures of the II category of lightning protection should be protected from direct lightning strikes, its secondary impacts and the introduction of high potentials through communications only in areas with an average intensity of lightning activity lch = 10.

Buildings and structures classified as category III according to the lightning protection device must be protected from direct lightning strikes and the introduction of high potentials through ground metal communications, in areas with lightning activity of 20 hours or more per year.

Buildings are protected from direct lightning strikes by lightning rods. The protection zone of a lightning rod is a part of the space adjacent to the lightning rod, inside which a building or structure is protected from direct lightning strikes with a certain degree of reliability. Protection zone A has a degree of reliability of 99.5% or more, and protection zone B has a degree of reliability of 95% or more.

Lightning rods consist of lightning rods (perceiving a lightning discharge), grounding conductors that serve to divert the lightning current to the ground, and down conductors connecting lightning rods to grounding rods.

Lightning rods can be free-standing or installed directly on a building or structure. According to the type of lightning rod, they are divided into rod, cable and combined. Depending on the number of lightning rods operating on one structure, they are divided into single, double and multiple.

Lightning rods of lightning rods are made of steel rods of various sizes and cross-sectional shapes. The minimum cross-sectional area of ​​the lightning rod is 100 mm2, which corresponds to a round section of a rod with a diameter of 12 mm, flat steel 35 x 3 mm or a gas pipe with a flattened end.

Lightning rods of wire lightning rods are made of steel multiwire cables with a cross section of at least 35 mm2 (diameter 7 mm).

Metal structures of protected structures can also be used as lightning rods - chimneys and other pipes, deflectors (if they do not emit combustible vapors and gases), metal roofing and other metal structures towering above a building or structure.

Down conductors are arranged with a cross section of 25-35 mm2 from steel wire with a diameter of at least 6 mm or steel of a strip, square or other profile. As down conductors, metal structures of protected buildings and structures (columns, trusses, fire escapes, elevator metal guides, etc.) can be used, except for prestressed reinforcement of reinforced concrete structures. Down conductors should be laid by the shortest paths to grounding conductors. The connection of down conductors with lightning rods and grounding conductors must ensure the continuity of the electrical connection in the connected structures, which, as a rule, is ensured by welding. Down conductors must be located at such a distance from the entrances to buildings that people cannot touch them in order to avoid being struck by lightning current.

Grounding conductors of lightning rods serve to drain the lightning current to the ground, and their correct and high-quality device depends effective work lightning protection.

The design of the earth electrode is adopted depending on the required impulse resistance, taking into account resistivity soil and the convenience of its laying in the ground. To ensure safety, it is recommended to fence off the grounding conductors or during a thunderstorm to prevent people from approaching the grounding conductors at a distance of less than 5-6 m. The grounding conductors should be located away from roads, sidewalks, etc.

Hurricanes are a marine phenomenon and the greatest destruction from them occurs near the coast. But they can also penetrate far ashore. Hurricanes can be accompanied by heavy rains, floods, in the open sea they form waves with a height of more than 10 m, storm surges. Tropical hurricanes are especially strong, the radius of winds of which can exceed 300 km (Fig. 22).

Hurricanes are a seasonal phenomenon. Every year, an average of 70 tropical cyclones develop on Earth. The average duration of a hurricane is about 9 days, the maximum is 4 weeks.

4. Storm

A storm is a very strong wind that causes great waves at sea and destruction on land. A storm can be observed during the passage of a cyclone, a tornado.

The wind speed near the earth's surface exceeds 20 m/s and can reach 100 m/s. In meteorology, the term "storm" is used, and when the wind speed is more than 30 m / s - a hurricane. Short-term wind amplifications up to speeds of 20-30 m/s are called squalls.

5. Tornadoes

A tornado is an atmospheric vortex that occurs 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.

For visual evaluation strength (speed) of the wind in points according to its effect on ground objects or on waves at sea, English Admiral F. Beaufort in 1806 developed a conditional scale, which, after changes and clarifications in 1963, was adopted by the World Meteorological Organization and is widely used in synoptic practice (table 20).

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

6. Impact of atmospheric phenomena on transport

atmosphere fog lightning hail hazard

Transport is one of the most weather-dependent branches of the national economy. This is especially true for air transport, for the normal operation of which the most complete, detailed information about the weather, both actually observed and expected according to the forecast, is required. The specificity of transport requirements for meteorological information lies in the scale of weather information - the routes of air, sea vessels and road freight transportation have a length measured by many hundreds and thousands of kilometers; in addition, meteorological conditions have a decisive influence not only on the economic performance of vehicles, but also on traffic safety; The life and health of people often depend on the state of the weather and the quality of information about it.

To meet the needs of transport in meteorological information, it turned out to be necessary not only to create special meteorological services (aviation and sea - everywhere, and in some countries also railway, road), but also to develop new branches of applied meteorology: aviation and marine meteorology.

Many atmospheric phenomena pose a danger to air and sea transport, while some meteorological quantities must be measured with particular accuracy to ensure the safety of modern aircraft and the navigation of modern ships. For the needs of aviation and the navy, new information was needed that climatologists did not have before. All this required a restructuring of what had already been and had become<классической>science of climatology.

The influence of transport needs on the development of meteorology over the past half century has become decisive, it entailed both the technical re-equipment of meteorological stations, and the use in meteorology of the achievements of radio engineering, electronics, telemechanics, etc., as well as the improvement of weather forecasting methods, the introduction of means and methods of precomputation the future state of meteorological quantities (atmospheric pressure, wind, air temperature) and the calculation of the movement and evolution of the most important synoptic objects, such as cyclones and their troughs with atmospheric fronts, anticyclones, ridges, etc.

This is an applied scientific discipline that studies the influence of meteorological factors on the safety, regularity and economic efficiency of aircraft and helicopter flights, as well as develops the theoretical foundations and practical methods for their meteorological support.

Figuratively speaking, aviation meteorology begins with the choice of the location of the airport, determining the direction and the required length of the runway at the aerodrome and sequentially, step by step, explores a whole range of issues about the state of the air environment that determines flight conditions.

At the same time, it also pays considerable attention to purely applied issues, such as scheduling flights, which should optimally take into account the state of the weather, or the content and form of transmission on board the landing aircraft of information about the characteristics of the surface air layer, which are crucial for landing safety. aircraft.

According to the International Organization civil aviation– ICAO, over the past 25 years, adverse meteorological conditions have been officially recognized as the cause of 6 to 20% of aviation accidents; in addition, in even more (one and a half times) number of cases, they were an indirect or concomitant cause of such incidents. Thus, in about a third of all cases of unfavorable completion of flights, weather conditions played a direct or indirect role.

According to ICAO, flight schedule disruptions due to weather over the past ten years, depending on the time of year and the climate of the area, occur on average in 1-5% of cases. More than half of these violations are flight cancellations due to adverse weather conditions at departure or destination airports. Recent statistics show that the lack of required weather conditions at destination airports accounts for up to 60% of cancellations, flight delays and aircraft landings. Of course, these are average numbers. They may not match the actual picture in certain months and seasons, as well as in certain geographical areas.

Cancellation of flights and return of tickets purchased by passengers, change of routes and additional costs arising from this, increase in flight duration and additional costs for fuel, consumption of motor resources, payment for services and flight support, depreciation of equipment. For example, in the USA and Great Britain, the losses of airlines due to the weather annually range from 2.5 to 5% of the total annual income. In addition, the violation of the regularity of flights causes moral damage to airlines, which ultimately also turns into a decrease in income.

Improving the on-board and ground equipment of aircraft landing systems makes it possible to reduce the so-called landing minima and thereby reduce the percentage of irregularities in the regularity of departures and landings due to adverse meteorological conditions at destination airports.

First of all, these are the conditions of the so-called weather minima - visibility range, cloud base height, wind speed and direction, set for pilots (depending on their qualifications), aircraft (depending on their type) and airfields (depending on their technical equipment and terrain characteristics). Under actual weather conditions below the established minimums, flights are prohibited for safety reasons. In addition, there are meteorological phenomena dangerous for flights that make it difficult or severely limiting the performance of flights (they are partially considered in Chapters 4 and 5). This is air turbulence that causes aircraft turbulence, thunderstorms, hail, aircraft icing in clouds and precipitation, dust and sand storms, squalls, tornadoes, fog, snow charges and blizzards, as well as heavy downpours that sharply impair visibility. Mention should also be made of the danger of static electricity discharges in clouds, snow drifts, slush and ice on the runway (runway) and insidious wind changes in the surface layer above the airfield, called vertical wind shear.

Among the large number of minima established depending on the qualifications of pilots, the equipment of aerodromes and aircraft, as well as the geography of the area, three categories of ICAO international minima for cloud height and visibility at the aerodrome can be distinguished, in accordance with which aircraft are allowed to take off and land in difficult weather conditions:

In civil aviation of our country, according to the current regulations, the following meteorological conditions are considered difficult: cloud height of 200 m or less (despite the fact that they cover at least half of the sky) and visibility range of 2 km or less. Such weather conditions are also considered difficult when there is one or more meteorological phenomena classified as dangerous for flights.

The standards for severe weather conditions are not standard: there are crews who are allowed to fly even under significantly worse weather conditions. In particular, all crews flying under ICAO minima of categories 1, 2 and 3 may fly in difficult meteorological conditions, if there are no dangerous meteorological phenomena that directly impede flights.

In military aviation, the restrictions on difficult meteorological conditions are somewhat less stringent. There are even so-called<всепогодные>aircraft equipped to fly in very difficult meteorological conditions. However, they also have weather restrictions. There is practically no complete independence of flights from weather conditions.

Thus,<сложные метеоусловия>- the concept is conditional, its standards are associated with the qualifications of the flight crew, the technical equipment of aircraft and the equipment of airfields.

Wind shear is the change in the wind vector (wind speed and direction) per unit distance. Distinguish between vertical and horizontal wind shear. Vertical shear is usually defined as a change in the wind vector in meters per second per 30 m height; depending on the direction of the wind change relative to the movement of the aircraft, the vertical shear can be longitudinal (following - positive or head - negative) or lateral (left or right). Horizontal wind shear is measured in meters per second per 100 km distance. Wind shear is an indicator of the instability of the state of the atmosphere, which can cause aircraft turbulence, interfere with flights, and even - at certain unit values ​​of its magnitude - threaten flight safety. Vertical wind shear of more than 4 m/s at 60 m altitude is considered a dangerous meteorological phenomenon for flights.

Vertical wind shear also affects the landing accuracy of the landing aircraft (Fig. 58). If the aircraft pilot does not parry its effect with the engine or rudders, then when the descending aircraft passes through the wind shear line (from the upper layer with one wind value to bottom layer with a different meaning), due to a change airspeed aircraft and its lift, the aircraft will deviate from the calculated descent trajectory (glide path) and land not at a given point on the runway, but further or closer to it, to the left or to the right of the runway axis.

Aircraft icing, that is, the deposition of ice on its surface or on individual structural details at the inlets of some instruments, occurs most often during a flight in clouds or rain, when supercooled water drops contained in a cloud or precipitation collide with the aircraft and freeze. Less often, there are cases of ice or frost deposition on the surface of an aircraft outside of clouds and precipitation, so to speak, in<чистом небе>. This phenomenon can occur in humid air that is warmer than the outer surface of the aircraft.

For modern aircraft, icing no longer poses a serious danger, since they are equipped with reliable anti-icing tools (electric heating of vulnerable areas, mechanical ice chipping and chemical protection surfaces). In addition, the frontal surfaces of aircraft flying at speeds of more than 600 km/h become very hot due to deceleration and compression of the air flow around the aircraft. This is the so-called kinetic heating of aircraft parts, due to which the surface temperature of the aircraft remains above the freezing point of water even when flying in cloudy air with a significant negative temperature.

However, intense icing of an aircraft during a forced long flight in supercooled rain or in clouds with a high water content is a real danger for modern aircraft. The formation of a dense crust of ice on the fuselage and empennage of the aircraft disrupts the aerodynamic qualities of the aircraft, as there is a distortion of the air flow around the surface of the aircraft. This deprives the aircraft of flight stability, reduces its controllability. Ice on the inlets of the engine air intake reduces the thrust of the latter, and on the air pressure receiver it distorts the readings of airspeed instruments, etc. All this is very dangerous if de-icing agents are not turned on in time or if the latter fail.

According to ICAO statistics, about 7% of all aviation accidents associated with meteorological conditions occur annually due to icing. This is slightly less than 1% of all air crashes in general.

In the air, no areas of space with a vacuum, or air pockets, can exist. But vertical gusts in a restless, turbulently disturbed flow cause the aircraft to throw, giving the impression of falling into voids. It was they who gave birth to this term, which is now out of use. The turbulence of an aircraft associated with air turbulence causes discomfort for passengers and the crew of the aircraft, makes it difficult to fly, and if it is too intense, it can also be dangerous for the flight.

Navigation has been closely related to the weather since ancient times. The most important meteorological quantities that determine the conditions for navigation of ships have always been the wind and the state of the sea surface due to it - excitement, horizontal visibility and phenomena that worsen it (fog, precipitation), the state of the sky - cloudiness, sunshine, visibility of stars, sun, moon . In addition, sailors are interested in air and water temperature, as well as the presence of sea ice in high latitudes, icebergs penetrating the waters of temperate latitudes. An important role for assessing navigation conditions is played by information about such phenomena as thunderstorms and cumulonimbus clouds, which are fraught with water tornadoes and strong squalls that are dangerous for marine vessels. In low latitudes, navigation is also associated with the danger that tropical cyclones carry with them - typhoons, hurricanes, etc.

Weather for sailors is first of all a factor determining the safety of navigation, then an economic factor, and, finally, as for all people, a factor of comfort, well-being and health.

Weather information—weather forecasts that include estimated wind, wave, and cyclonic eddy positions, both low-latitude and extra-tropical—is critical to maritime navigation, that is, to laying out routes that provide the fastest, most cost-effective navigation with minimal risk. for ships and cargo and with maximum safety for passengers and crews.

Climatic data, that is, information about the weather accumulated over many previous years, serve as the basis for laying maritime trade routes linking the continents. They are also used in the scheduling of passenger ships and in the planning of maritime transport. Weather conditions must also be taken into account when organizing loading and unloading operations (when it comes to goods subject to the influence of atmospheric conditions, such as tea, forests, fruits, etc.), fishing, tourist and excursion business, sports navigation.

Icing of ships is a scourge of navigation in high latitudes, however, at air temperatures below zero, it can also occur in middle latitudes, especially with strong winds and waves, when there is a lot of spray in the air. Main danger icing is to increase the center of gravity of the vessel due to the growth of ice on its surface. Intense icing makes the vessel unstable and creates a real risk of capsizing.

The rate of ice deposition during freezing of supercooled water splashes on fishing trawlers in the North Atlantic can reach 0.54 t/h, which means that after 8-10 hours of navigation in conditions of intense icing, the trawler will capsize. A somewhat lower rate of ice deposition in snowfalls and supercooled fog: for a trawler, it is respectively 0.19 and 0.22 t/h.

The icing reaches its greatest intensity in those cases when the ship was previously in an area with an air temperature significantly below 0°C. An example of hazardous icing conditions in temperate latitudes can serve as the Tsemess Bay on the Black Sea, where during strong northeast winds, with the so-called Novorossiysk pine forest, in winter, freezing of water aches and splashes of sea water on the hulls and deck superstructures of ships occurs so intensely that the only effective way to save the ship is to go into open sea, beyond the impact of bora.

According to special studies conducted in the 1950s and 1960s, a tailwind increases the ship's speed by about 1%, while a headwind can reduce it, depending on the size of the ship and its load, by 3-13%. Even more significant is the impact on the ship of sea waves caused by the wind: the speed of the ship is an elliptical function of the height and direction of the waves. On fig. 60 shows this relationship. With a wave height of more than 4 m, ships are forced to slow down or change course. In conditions of high waves, the duration of navigation, fuel consumption and the risk of damage to cargo increase sharply, therefore, based on meteorological information, the route is laid around such areas.

Poor visibility, fluctuations in the water level in rivers and lakes, freezing of water bodies - all this affects both the safety and the regularity of navigation of ships, as well as economic indicators their operation. Early ice formation on the rivers, as well as late opening of the rivers from ice, shortens the navigation period. The use of icebreakers lengthens the time of navigation, but increases the cost of transportation.

Deterioration of visibility due to fog and precipitation, snow drifts, ice phenomena, downpours, floods and strong winds hinder the operation of road and rail transport, not to mention motorcycles and bicycles. Open modes of transport are more than twice as sensitive to adverse weather as closed ones. On days with fog and heavy precipitation, the flow of cars on the roads is reduced by 25-50% compared to the flow on clear days. The number of private cars decreases most sharply on the roads on rainy days. For this reason, it is difficult to establish an exact quantitative relationship between meteorological conditions and traffic accidents, although such a relationship undoubtedly exists. Despite the decrease in the flow of vehicles in bad weather, the number of accidents in icy conditions increases by 25% compared to dry weather; Especially frequent are accidents on icy roads on bends in the road with heavy traffic.

IN winter months in temperate latitudes, the main difficulties for land transport are associated with snow and ice. Snow drifts require road clearing, which complicates traffic, and the installation of barrier shields on road sections that do not have snow-protected plantings.

A shield placed vertically and oriented perpendicular to the air flow with which the cier is transferred (gives off a zone of turbulence, that is, an unordered vortex air movement (Fig. 61). Within the turbulent zone, instead of transfer it's snowing the process of its deposition - a snowdrift grows, the height of which, in the limit, coincides with the thickness of the turbulence zone, and the length coincides with the extent of this zone, which, as established by experience, is approximately equal to fifteen times the height of the shield. The snowdrift that forms behind the shield resembles a fish in shape.

The formation of an ice crust on roads is determined not only by the temperature regime, but also by humidity, the presence of precipitation (in the form of supercooled rain or drizzle falling on a previously very chilled surface). Therefore, based on air temperature alone, it is risky to draw a conclusion about sleet on the roads, however, the temperature regime remains the most important indicator of the danger of icing roads: the minimum temperature of the road surface can be 3 ° C lower than the minimum air temperature.

The salt that is spread on the roads and on the sidewalks does indeed prevent the formation of an ice crust by melting the snow. A mixture of snow and salt remains a liquid non-freezing mass at temperatures down to -8 ° C, the melting of ice by salt can be achieved even at a temperature of -20 ° C, although the melting process will be much less effective than at temperatures close to 0 ° C . In practice, clearing roads from snow with the help of salt is effective when the snow cover is up to 5 cm thick.

However, the use of salt to clear roads from snow has a negative side: salt causes corrosion of cars and pollutes water bodies with chlorides, and soil near roads with excess sodium (see also 13.10). Therefore, in a number of cities this method of dealing with icing of roads is prohibited.

Fluctuations in air temperature in winter time can cause icing of rails and communication lines, as well as rolling stock when it is on sidings; there are, although relatively rare, cases of icing of pantographs on electric trains. All these features of the influence of meteorological conditions on the operation of railway transport require the use of special equipment and are associated with additional labor costs and Money in the amount of 1-2% of the cost of operational operating costs. In general, rail transport is less dependent on weather conditions than other modes of transport; it is not for nothing that advertising brochures railways often claim that<железная дорога работает и тогда, когда все другие виды транспорта бездействуют>. Although this is an exaggeration, it is not too far from the truth. However, from natural disasters caused by weather anomalies, railways are not insured in the same way as other sectors of the national economy: strong storms, floods, landslides, mudflows, snow landslides destroy railways, as well as highways; ice, intensively deposited on the contact wires of electric railways, breaks them in the same way as the wires of power lines or conventional communication lines. It should be added that the increase in the speed of trains up to 200-240 km/h gave rise to the threat of the train overturning under the influence of the wind.

In hilly areas, to reduce snow drifts, barrier shields are installed, the slope of the canvas is changed, which helps to weaken the surface vortex, or low embankments are constructed. The embankment must not be too steep, otherwise a noticeable leeward vortex is created, and this leads to the accumulation of snow on the lee side of the embankment.

Bibliography

1. Mankov V. D.: BZD, part II, BE EVT: tutorial for higher education institutions - St. Petersburg: VIKU, 2001

2. Kosmin G. V., Mankov V. D. Guide to the State Law on the discipline "BZhD", part 5. About the conduct of hazardous work and ET Gostekhnadzor in the Armed Forces of the Russian Federation - VIKU - 2001

3. O. Rusak, K. Malayan, N. Zanko. "Life Safety" study guide

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.

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 - 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.

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.

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 lasts for a few seconds, but can cause destruction and loss of life. In the Moscow region, for example, annually due to lightning discharges in summer period there are about 50 fires.

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.

Most often, lightning occurs in cumulonimbus clouds. The American physicist B. Franklin (1706-1790), Russian scientists M.V. Lomonosov (1711-1765) and G. Richman (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 electric 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
5 ∙10 7 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 earth's surface at an average speed of 2∙10 5 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 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.

Atmospheric hazards

hazardous natural, meteorological processes and phenomena arising 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. .

Edwart. Glossary of terms of the Ministry of Emergency Situations, 2010

See what "Atmospheric hazards" are in other dictionaries:

GOST 28668-90 E: Low-voltage distribution and control devices. Part 1: Requirements for devices tested in whole or in part- Terminology GOST 28668 90 E: Low-voltage complete distribution and control devices. Part 1. Requirements for devices tested in whole or in part original document: 7.7. Internal separation of the ASSEMBLY with fences or partitions ... ...

Typhoon- (Taifeng) Natural phenomenon typhoon, causes of typhoon Information about the natural phenomenon typhoon, causes and development of typhoons and hurricanes, the most famous typhoons Content is a kind of tropical whirlwind, ... ... Encyclopedia of the investor

GOST R 22.0.03-95: Safety in emergency situations. natural emergencies. Terms and Definitions- Terminology GOST R 22.0.03 95: Safety in emergency situations. natural emergencies. Terms and definitions original document: 3.4.3. vortex: atmospheric education with rotational movement of air around a vertical or ... ... Dictionary-reference book of terms of normative and technical documentation

scheme- 2.59 schema description of the content, structure and constraints used to create and maintain a database. Source: GOST R ISO/IEC TR 10032 2007: Data management reference model 3.1.17 schema: A document that shows in the form of ... ... Dictionary-reference book of terms of normative and technical documentation

KANA REACTION- KANA REACTION, see Precipitation. SEWER. Contents: The history of the development of K. and modern, the state of the canal. constructions in the USSR and abroad 167 Systems K. and a dignity. requirements for them. Wastewater. "The conditions for releasing them into water bodies .... 168 San. ... ... Big Medical Encyclopedia

Scientific classification ... Wikipedia

From a national point of view, it is very important to have as accurate information as possible about the movement of population in general and, in particular, about the number of deaths occurring in the country during a known period of time. Matching… … Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

A set of organizational and technical measures for the collection, transportation and disposal of waste generated in the territory of populated areas. It also includes summer and winter cleaning of streets, squares and courtyards. Waste… …

Waters polluted with domestic waste and industrial waste and removed from the territories of populated areas and industrial enterprises sewerage systems (See Sewerage). To S. in. also include water resulting from ... ... Great Soviet Encyclopedia

This page needs a major overhaul. It may need to be wikified, expanded, or rewritten. Explanation of the reasons and discussion on the Wikipedia page: For improvement / May 21, 2012. Date of setting for improvement May 21, 2012 ... Wikipedia

Books

• Metro 2033, Glukhovsky D. Twenty years after the Third World War, the last survivors hide in the stations and tunnels of the Moscow metro, the largest anti-nuclear bomb shelter on Earth. Surface…