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To predict dangerous phenomena, Roshydromet has developed criteria - according to them, experts determine the degree of danger of an impending or already occurring disaster. A total of 19 weather phenomena have been identified that may pose a serious threat.
Element #1: Wind
Very strong wind(at sea - a storm). The speed of the elements exceeds 20 meters per second, and with gusts it increases by a quarter. For high-altitude and coastal areas, where winds are more frequent and intense, the standard is 30 and 35 meters per second, respectively.
In Russia, Primorye, the North Caucasus and the Baikal region suffer from storms more often than other regions. The strongest winds blow in the archipelago New Earth, the islands of the Sea of Okhotsk and in the city of Anadyr on the edge of Chukotka: the speed of the air flow often exceeds 60 meters per second.
Hurricane- the same as a strong wind, but even more intense - with gusts, the speed reaches 33 meters per second. During a hurricane, it is better to be at home - the wind is so strong that it can knock a person down and cause injuries.
Hurricane May 29 current year in Moscow became the largest in terms of the number of victims in the last hundred years. During the hurricane on May 29, the wind speed in some areas of the capital reached 25 m/s. More than 10 people died, more than a hundred were injured.
Squall- wind speed of 25 meters per second, not weakening for at least a minute. It poses a threat to life and health, can damage infrastructure, cars and houses.
Tornado- a vortex in the form of a pillar or cone, heading from the clouds to the surface of the Earth. On July 31, 2011, in Blagoveshchensk, Amur Region, a tornado overturned three trucks, damaged more than 50 support poles, roofs of houses, non-residential buildings and broke 150 trees.
A meeting with a whirlwind can be the last in life: inside its funnel, the speed of air flows can reach 320 meters per second, approaching the speed of sound (340.29 meters per second), and the pressure can drop to 500 millimeters of mercury (the norm is 760 mm Hg). st). Caught in the range of this powerful "vacuum cleaner" objects rise into the air and rush through it at great speed.
frost called a temporary decrease in the temperature of the soil or air near the ground to zero (against the background of positive average daily temperatures).
hard frost registered when the temperature reaches a dangerous value. Each region usually has its own.
If in the period from October to March the average daily temperature is seven degrees below the long-term norm, it means that abnormal cold. Such weather leads to accidents in housing and communal services, as well as to the freezing of crops and green spaces.
Element number 2: water
Heavy rain. If more than 30 millimeters of rain fell in an hour, such weather is classified as a heavy downpour. It is dangerous because the water does not have time to go into the ground and drain into the rain sewer. Heavy rains form powerful streams that paralyze traffic on the roads. Washing away the soil, water masses bring down metal structures to the ground. In hilly or ravine-dissected areas, heavy rainfall increases the risk of mudflows.
If at least 50 millimeters of precipitation falls in 12 hours, meteorologists classify this phenomenon as "Highly heavy rain», which can also lead to the formation of mudflows. For mountainous areas, the critical indicator is 30 millimeters, since the likelihood of catastrophic consequences is higher there.
Powerful mud stream with fragments of stones is a mortal danger: its speed can reach six meters per second, and the “head of the elements”, the leading edge of the mudflow, is 25 meters in height.
In July 2000, a powerful mudflow hit the town of Tyrnyanz in Karachay-Cherkessia. 40 people were missing, eight were killed, eight more were hospitalized. Residential buildings and infrastructure of the city were damaged.
Continuous heavy rain. Precipitation that fell within half or a whole day should exceed the mark of 100 millimeters, or 120 millimeters in two days. For rainy areas, the norm is 60 millimeters.
The probability of flooding, flushing and convergence of mudflows during prolonged heavy rain increases dramatically.
Very heavy snow. This type of dangerous phenomenon means heavy snowfall, as a result of which more than 20 millimeters of precipitation falls in 12 hours. This amount of snow blocks roads and makes it difficult for cars to move.
hail It is considered large if the diameter of the ice balls exceeds 20 millimeters. it weather phenomenon represents a serious danger to property and human health. Hailstones falling from the sky can damage cars, shatter windows, destroy vegetation, and destroy crops.
In August 2015, hail hit the Stavropol Territory, accompanied by heavy rain and wind. Eyewitnesses filmed hailstones the size of egg and five centimeters in diameter!
strong blizzard called a weather phenomenon in which for half a day the visibility from flying snow is up to 500 meters, and the wind speed does not drop below 15 meters per second. During the rampage of the elements, driving becomes dangerous, flights are canceled.
Heavy fog or mist, are the conditions under which for 12 hours or more visibility is from five to zero meters. The reason for this may be a suspension of tiny drops of water with a moisture content of up to one and a half grams of water per cubic meter of air, soot particles and tiny ice crystals.
Meteorologists determine atmospheric visibility using a special technique or using a transmissometer device.
Heavy ice. This weather phenomenon is recorded by a special device - an icing machine. Among characteristic features this bad weather - ice with a thickness of 20 millimeters, wet, non-melting snow 35 millimeters high or frost half a centimeter thick.
Ice provokes many accidents and leads to casualties.
Element number 3: earth
Dust storm It is recorded by meteorologists when for 12 hours dust and sand carried by the wind at a speed of at least 15 meters per second impair visibility at a distance of up to half a kilometer.
Element number 4: fire
Abnormal heat It is recorded by meteorologists when in the period from April to September for five days the average daily temperature is seven degrees above the climatic norm of the region.
The UN Office for Disaster Risk Reduction noted that from 2005 to 2014, more than 7,000 people died from the effects of heat waves.
Heatwave- the temperature exceeds the established dangerous threshold in the period from May to August (the critical value for each territory is different).
This leads to droughts, increased fire risk and heat stroke.
Extreme fire hazard. This type of dangerous phenomenon is declared at high air temperature, associated with a lack of precipitation.
Storms and hurricanes
The uneven heating of the atmosphere leads to a change atmospheric pressure and, as a result, causes a general circulation of air in the atmosphere, which predetermines the characteristics of the climate, weather, the possibility and frequency of meteorological emergencies.
The area of low atmospheric pressure with a minimum in the center is called a cyclone. A cyclone in diameter reaches several thousand kilometers. Cyclones form cloudy weather with strong winds.
Storms and hurricanes occur during cyclones. The wind speed near the earth's surface exceeds 20 m/s and can reach 100 m/s.
The danger of these natural phenomena is created as a result of dynamic load from the flow of air masses. The destruction of buildings, structures and other objects, the defeat of people occurs as a result of the action of high-speed air pressure, which causes significant pressure on objects.
To characterize the strength of the wind, the 12-point Beaufort scale is often used, which is based on the characteristic consequences of the action of the wind on the earth's surface (Table 2.2).
Table 2.2 - Beaufort scale
| Points | Wind speed m/s | Wind characteristic | Effects of the wind |
| 0-0,5 | calm | the leaves on the trees do not move, the smoke from the chimneys rises vertically | |
| 0,5-1,7 | quiet | the smoke deviates a little, the wind is almost not felt | |
| 1,7-3,3 | light | feel the slight breeze | |
| 3,3-5,2 | weak | swaying small branches | |
| 5,2-7,4 | moderate | dust rises, branches of medium thickness sway | |
| 7,4-9,8 | big enough | thin trees and thick branches sway, ripples form on the water | |
| 9,8-12 | strong | swaying thick tree trunks | |
| 12,0-15,0 | very strong | swing big trees, it's hard to go against the wind | |
| 15,0-18,0 | extremely strong | thick tree trunks break | |
| 18,0-22,0 | storm | destroyed light buildings, fences | |
| 22,0-25,0 | heavy storm | rather strong buildings are destroyed, the wind uproots trees | |
| 25,0-29,0 | fierce storm | significant damage, overturned wagons, cars | |
| over 29 | Hurricane | destroyed brick houses, stone fences |
Storms divided into vortex, dust and stream (storm at sea) - wind force of 9-11 points, wind speed of 20-32 m / s causes damage to buildings, uproots trees, overturns cars, destroys overhead communication lines and power lines. The defeat of people occurs as a result of damage to buildings, overturning machines and mechanisms, falling trees.
Hurricane - wind force 12 points, wind speed 32-60 m / s, sometimes up to 100 m / s - destroys and devastates everything in its path.
For security during a storm and a hurricane, a "Storm Warning" is issued. According to this message, access to the sea of floating craft is limited, tower cranes and other construction mechanisms of large dimensions are fixed by "storm", movement is limited Vehicle, stop logging, field work, etc. In addition, preventive measures at enterprises provide for the strengthening of structures, buildings, cleaning or securing objects that can injure people, and take measures to preserve equipment.
Doors and windows are tightly closed in private houses, apartments and industrial premises. Objects are taken from roofs, loggias, balconies, which, due to gusts of wind, can fall down and injure people. Items located in the yards are fixed or brought into the room.
A storm (hurricane) may be accompanied by a thunderstorm. At the same time, it is necessary to avoid situations in which the possibility of lightning strikes increases.
Forecasting and warning of a storm (hurricane) is carried out by the hydrometeorological service using modern instruments, including meteorological satellites, which record the occurrence of extreme meteorological phenomena, after which the possible direction of their movement, probable power and time of approach to a certain area are calculated. The administrative bodies of regions, districts, civil protection headquarters, agricultural, forestry and industrial facilities are notified of the approach of a hurricane (storm). local authorities the authorities notify the population, and the heads of enterprises and the headquarters of the state defense - workers. This makes it possible to alert the formations of civil protection in time, to carry out preventive work in areas of possible action of a hurricane or storm, and to effectively eliminate the consequences of a natural disaster.
In the area of a hurricane, storm, tornado, civil protection formations and the population must be prepared for:
Carrying out the evacuation of the population and material assets from dangerous areas;
Rescuing people; search and release of victims from under destroyed buildings and structures;
The provision of first aid and the delivery of victims to medical institutions;
extinguishing fires;
Elimination of accidents at production facilities and utility networks.
hail
hail - precipitation in the form of ice particles of irregular shape. Intense hail destroys agricultural crops, and especially large hail leads to the destruction of roofs, damages cars, can cause serious injury or even death.
Smog
chemical reactions, which occur in the air lead to the formation of smoky smog. Smog occurs under the following conditions: firstly, atmospheric pollution as a result of intense intake of dust, smoke, exhaust and industrial gases, and other products in the form of fine particles that cities emit into the air, and secondly, the long existence of anticyclones, in which pollutants accumulate in the surface layer of the atmosphere. Great smoke, which in its effect is similar to smog, also occurs at large forest fires. Smog and smoke exacerbate chronic lung diseases, deterioration in well-being, cause determined material damage associated with the removal of plaque on equipment located on the street, windows, and the like.
There are three layers of smog:
Lower, located in the surface layers of air. It is formed mainly from the exhaust gases of transport and the redistribution of dust raised into the air;
The second layer is formed due to emissions from heating systems, located at a height of about 20-30 m above the ground;
The third layer is located at a height of 50-100 m or more and is formed mainly as a result of emissions from industrial enterprises. Smog is quite toxic.
Lightning
Lightning and discharges are to some extent associated with matter in the plasma state. Lightning is linear and ball.
Linear lightning occurs when the electric field strength between the clouds and the ground increases. Linear lightning parameters:
Length - no more than 10 km;
Channel diameter - up to 40 cm;
Current strength - 105-106 A;
Time of one lightning discharge - 10 -4 s;
The temperature in the lightning channel is up to 10,000°K.
A lightning strike, as a result of its thermal and electrodynamic action, can cause injury and death of people, destruction of structures, fire. The greatest damage occurs from lightning strikes to ground objects in the absence of a lightning rod or other good conductors between the strike site and the ground. When a lightning strikes, from an electrical breakdown in the material, channels appear in which a high temperature is formed and part of the material evaporates, followed by an explosion and fire. In addition to the direct action of lightning, during a strike, a significant difference in electrical potentials between individual objects may occur, which can lead to electric shock to people.
Protection against lightning is carried out with the help of lightning rods, which are equipped with all houses and buildings. The degree of protection depends on the purpose of the house or structure, the intensity of thunderstorm activity in the area and the expected reliability of the object being struck by lightning.
Ball lightning is generated when powerful linear lightning strikes, they have a diameter of about 30 cm, their light emission is approximately equal to 100 W of a light bulb, the luminous flux is ~ 1400 lumens, the thermal radiation is small, the speed of movement is 3-5 m/s, sometimes up to 10 m/s, the energy released during the explosion is about 10,000 J. Ball lightning is often attracted to metal objects, its decay occurs in most cases by an explosion, but it can also simply fade and fall apart. The explosion of ball lightning is not powerful, but it can cause burns, objects torn off by the explosion are dangerous. The result of the action of ball lightning can be a fire.
Personal safety during an encounter with ball lightning, you need to sit or stand still, watching it. If the lightning approaches, you can blow on it - the lightning will fly away. In any case, it is necessary to move as far as possible from ball lightning, since the "behavior" of lightning is unpredictable.
Dangerous meteorological phenomena - these are natural processes and phenomena that occur in the atmosphere, which, by their intensity (strength), scale of distribution and duration, have or can have a damaging effect on people, farm animals and plants, economic objects and the natural environment.
These phenomena include:
1. Very strong wind
The average wind speed is not less than 20 m/s, on the coast of the seas and in mountainous areas not less than 25 m/s. Instantaneous wind speed (gust) not less than 25 m/s, on the coast of the seas and in mountainous areas not less than 30 m/s.
A sharp short-term increase in wind. Instantaneous wind speed (gust) over 25 m/s for at least 1 minute.
strong small scale atmospheric vortex in the form of a pillar or funnel, directed from the cloud to the surface of the earth
4. Heavy rain
Heavy rain shower. The amount of liquid precipitation is not less than 30 mm for a period of not more than 1 hour
5. Very heavy rain
Significant liquid and mixed precipitation (rain, heavy rain, sleet, snow with rain). The amount of precipitation is not less than 20 mm for a period of not more than 1 hour
6. Very heavy snow
Significant solid precipitation (snow, heavy snow, etc.). The amount of precipitation is not less than 20 mm for a period of not more than 12 hours.
7. Continuous heavy rain
Rain continuous (with interruptions no more than 1 hour) for several days. The amount of precipitation is not less than 120 mm for a period of at least 2 days.
8. Large hail
Hailstone diameter over 20 mm
9. Strong snowstorm
General or blowing snow during strong wind causing a significant reduction in visibility. Average wind speed not less than 15 m/s, MWD not more than 500 meters
10. Strong dust storm
The transport of dust or sand in high winds, causing a severe deterioration in visibility. The average wind speed is not less than 15 m/s, MWD is not more than 500 meters.
11. Heavy fog
Fog with a significant reduction in visibility. MDV no more than 50 meters
12. Icy frost deposits
Strong deposits on the wires of street lighting (icing machine). Diameter, mm, not less than: Ice 20, Complex deposit 30, Wet snow 35, Frost 50.
13. Extreme heat
High maximum air temperature for a long period of time. The maximum air temperature is not less than 35°C for 5 days.
14. Hard frost
Low minimum air temperature for a long time. The minimum temperature is not more than -35°C for 5 days.
In addition to HH, there are also hydrometeorological phenomena that significantly impede or hinder the activities of individual enterprises and sectors of the economy, but do not reach the HH criteria in terms of their values. The criteria for these phenomena are developed taking into account the division by strength and intensity specified in RD 52.27.724-2009 "Manuals on short-range weather forecasts general purpose”, developed, approved and put into effect on March 1, 2010 by Roshydromet. Hydrometeorological phenomena are selected depending on the type of activity of a particular enterprise, organization or sector of the economy and refer to the types of specialized hydrometeorological services. * (data from the hydrometeorological center Russian Federation)
Ministry of Education and Science of the Russian Federation
Stateeducational institution of higher professional building
« Taganrog State Pedagogical Institute »
Abstract on the topic:
Performed:
1st year student of C12 group
Faculty of Social Pedagogy
Volchanskaya Natalya
Taganrog
2011
Content:
- Introduction.
Natural disasters.
Hurricanes, storms, tornadoes.
- Conclusion.
- Introduction.
Natural disasters have threatened the inhabitants of our planet since the beginning of civilization. Somewhere more, elsewhere less. There is no 100% security anywhere. Natural disasters can cause enormous damage.
AT last years more and more natural disasters occur on the planet. Most often, destruction is brought by: storms, hurricanes, tornadoes, tornadoes.
AT modern world this issue is the most pressing. Meteorological hazards bring enormous damage to nature, housing and agriculture.
Natural emergencies (natural disasters) have been on the rise in recent years. Ice, snowdrifts, storms, hurricanes and tornadoes visit Russia every year.
aim my essay is the study of natural emergencies.
The task of my work- consideration of the classification of natural emergencies, the actions of the population during emergencies.
- Natural disasters.
Natural disasters include: hurricanes, tornadoes, tornadoes, snowdrifts and avalanches, prolonged heavy rains, severe persistent frosts.
Over the last 20 years of the 20th century, more than 800 million people in the world suffered from natural disasters (over 40 million people a year), more than 140 thousand people died, and the annual material damage amounted to more than 100 billion dollars.
Two natural disasters in 1995 are good examples.
- San Angelo, Texas, USA, May 28, 1995: tornadoes and hail hit a city of 90,000; the damage caused is estimated at 120 million US dollars.
Accra, Ghana, July 4, 1995: The heaviest rainfall in almost 60 years caused severe flooding. About 200,000 residents lost all their possessions, more than 500,000 more could not get into their homes, and 22 people died.
storms (9 - 11 points);
hurricanes and storms (12 - 15 points);
tornadoes, tornadoes (a kind of tornado in the form of a part of a thundercloud).
- Hurricanes, storms, tornadoes.
Bu? Rya (Who? Rm)- very strong wind , as well as a large excitement at sea . Also, in the course of numerous observations by American scientists, it was found that for areas located in northern latitudes, a winter hurricane can be considered a snow storm, during which the wind speed reaches 56 kilometers per hour. In this case, the air temperature drops to? 7 ° C. The area of distribution of a snow storm can be arbitrarily vast.
The storm can be observed:
- during the passage of tropical or extratropical cyclone;
during the passage of a tornado (thrombus, then rnado);
during a local or frontal thunderstorm.
Storms include winds with a speed of more than 20 m / s, that is, more than 9 points according to Beaufort scale.
Distinguish:
by intensity:
- strong storm with a speed of 24.5-28.4 m/s (10 points);
severe storm with a speed of 28.5-32.6 m/s (11 points).
- subtropical storm
tropical storm
Hurricane ( Atlantic Ocean)
- Typhoon (Pacific Ocean).
Storms and hurricanes occur during the passage of deep cyclones and represent the movement of air masses (wind) at great speed. During a hurricane, the air speed exceeds 32.7 m/s (more than 118 km/h). Sweeping over the earth's surface, the hurricane breaks and uproots trees, rips off roofs and destroys houses, power lines and communications, buildings and structures, disables various equipment. As a result of a short circuit in the power grid, fires occur, the supply of electricity is interrupted, the operation of objects stops, and other harmful consequences may occur. People may find themselves under the rubble of destroyed buildings and structures. Fragments of destroyed buildings and structures and other objects flying at high speed can cause serious injuries to people.
Hurricanes begin with thunderstorms, collide with trade winds - winds of tropical latitudes.During hurricanes, the width of the zone of catastrophic destruction reaches several hundred kilometers (sometimes thousands of kilometers). The hurricane lasts 9 - 12 days, causing a large number of casualties and destruction. The transverse size of a tropical cyclone is much smaller - only a few hundred kilometers, its height is up to 12-15 km. Pressure in hurricanes falls much lower than in an extratropical cyclone. At the same time, the wind speed reaches 400-600 km/h. In the core of the tornado, the pressure drops very low, so the tornadoes "suck" various, sometimes very heavy objects into themselves, which are then carried over long distances. People caught in the center of the tornado die.
Reaching the highest stage, the hurricane goes through 4 stages in its development: tropical cyclone, baric depression, storm, intense hurricane.
Hurricanes form, as a rule, over the tropical part of the North Atlantic, often from west coast Africa, and are gaining strength, moving to the west. A large number of incipient cyclones develop in this manner, but on average only 3.5 percent of them reach the tropical storm stage. Only 1-3 tropical storms, usually over the Caribbean Sea and the Gulf of Mexico, reach the east coast of the United States each year.
A hurricane is not inferior to earthquakes in terms of its impact on the environment: buildings, masts of power transmission lines and communications, transport routes are destroyed, trees are broken and twisted, ships and vehicles are overturned. Storms and hurricanes are often accompanied by downpours and snowfalls, which further complicates the situation. As a result of strong winds, a wind surge of water occurs at the estuarine section of the rivers, settlements and arable land are flooded, enterprises are forced to stop their production.
Many hurricanes originate off the west coast of Mexico and move northeast, threatening coastal Texas.
The conditions necessary for the birth of a hurricane are not completely known. The following is known: an intense hurricane is almost correctly rounded in shape, sometimes reaching 800 kilometers in diameter. Inside the tube of super-warm tropical air is the so-called "eye" - a space of pure blue sky about 30 kilometers in diameter. It is surrounded by the "wall of the eye" - the most dangerous and restless place. It is here that swirling inward, moisture-saturated air rushes upward. In doing so, it causes condensation and the release of dangerous latent heat - the source of the storm's strength. Rising kilometers above sea level, the energy is released to the peripheral layers. In the place where the wall is located, ascending air currents, mixing with condensation, form a combination of maximum wind force and violent acceleration.
The clouds spiral around this wall parallel to the direction of the wind, thus giving the hurricane its characteristic shape and changing from heavy rain at the center of the hurricane to tropical downpour at the edges.
A hurricane on land destroys buildings, communication and power lines, damages transport communications and bridges, breaks and uproots trees; when propagating over the sea.
In December 1944, 300 miles east of about. Luzon (Philippines) ships of the US 3rd Fleet were in the area near the center of the typhoon. As a result, 3 destroyers sank, 28 other ships were damaged, 146 aircraft carriers and 19 seaplanes on battleships and cruisers were wrecked, damaged and washed overboard, over 800 people died.
From hurricane winds of unprecedented strength and gigantic waves that hit the coastal regions of East Pakistan on November 13, 1970, a total of about 10 million people were affected, including about 0.5 million people who died and went missing.
Hurricane Katrina most destructive hurricane in history and usa . It happened at the end of August 2005. The heaviest damage was caused New Orleans in Louisiana , where about 80% of the city's area was under water. As a result of the disaster, 1,836 residents were killed and the economic damage amounted to $125 billion.
The hurricane that hit Bangladesh in 1991 claimed the lives of 135,000 people.
Tornado- one of the cruel, destructive phenomena of nature. According to V.V. Kushina, a tornado is not a wind, but a “trunk” of rain twisted into a thin-walled pipe, which rotates around an axis at a speed of 300-500 km / h. Due to centrifugal forces, a vacuum is created inside the pipe, and the pressure drops to 0.3 atm. If the wall of the "trunk" of the funnel breaks, bumping into an obstacle, then outside air rushes into the funnel. Pressure drop 0.5 atm. accelerates the air secondary flow to speeds of 330 m/s (1200 km/h) and more, i.е. to supersonic speeds. Tornadoes are formed in an unstable state of the atmosphere, when the air in the upper layers is very cold, and in the lower layers it is warm. There is an intense air exchange, accompanied by the formation of a vortex of great strength.
Such whirlwinds arise in powerful thunderclouds and are often accompanied by thunderstorms, rain, and hail. Obviously, it cannot be said that tornadoes arise in every thundercloud. As a rule, this happens on the verge of fronts - in the transition zone between warm and cold air masses. It is not yet possible to predict tornadoes, and therefore their appearance is unexpected.
The tornado does not live long, since rather soon the cold and warm air masses mix, and thus the reason supporting it disappears. However, even in a short period of its life, a tornado can cause enormous damage.
Until now, the tornado is in no hurry to reveal its other secrets. So, there are no answers to many questions. What is a tornado funnel? What gives its walls a strong rotation and tremendous destructive power? Why is the tornado stable?
It is not only difficult to study a tornado, but also dangerous - upon direct contact, it destroys not only the measuring equipment, but also the observer.
Comparing descriptions of tornadoes (tornadoes) of the past and present centuries in Russia and other countries, one can see that they develop and live according to the same laws, but these laws have not been fully elucidated and the behavior of a tornado seems unpredictable.
During the passage of tornadoes, of course, everyone hides, runs, and people are not up to observing, and even more so measuring the parameters of tornadoes. The little that we managed to find out about the internal structure of the funnel is due to the fact that the tornado, breaking away from the ground, passed over the heads of people, and then it was possible to see that the tornado is a huge hollow cylinder, brightly lit inside by the brilliance of lightning. A deafening roar and buzzing is heard from within. It is believed that the wind speed in the walls of the tornado reaches the sound.
A tornado can suck in and lift up a large portion of snow, sand, etc. As soon as the speed of snowflakes or grains of sand reaches a critical value, they will be thrown out through the wall and can form a kind of case or cover around the tornado. characteristic feature This case-cover is that the distance from it to the wall of the tornado along the entire height is approximately the same.
Let us consider, as a first approximation, the processes arising in thunderclouds. Abundant moisture entering the cloud from the lower layers releases a lot of heat, and the cloud becomes unstable. Rapid ascending currents of warm air arise in it, which carry masses of moisture to a height of 12-15 km, and equally rapid cold descending currents that fall down under the weight of the formed masses of rain and hail, strongly cooled in the upper layers of the troposphere. The power of these streams is especially great due to the fact that two streams simultaneously arise: ascending and descending. On the one hand, they do not experience resistance environment, because the volume of air going up is equal to the volume of air going down. On the other hand, the expenditure of energy by the flow to lift water up is completely replenished when it falls down. Therefore, flows have the ability to accelerate themselves to enormous speeds (100 m/s or more).
In recent years, another possibility has been identified for the rise of large masses of water into the upper troposphere. Often, when air masses collide, vortices are formed, which, for their relatively small size, are called mesocyclones. The mesocyclone captures a layer of air at a height of 1-2 km to 8-10 km, has a diameter of 8-10 km and rotates around a vertical axis at a speed of 40-50 m/s. The existence of mesocyclones has been reliably established, and their structure has been studied in sufficient detail. It has been found that in mesocyclones a powerful thrust arises on the axis, which ejects air to heights of up to 8-10 km and above. Observers have found that it is in the mesocyclone that a tornado sometimes originates.
The most favorable environment for the origin of the funnel is fulfilled when three conditions are met. First, the mesocyclone must be formed from cold, dry masses of air. Secondly, the mesocyclone must enter the area where a lot of moisture has accumulated in the surface layer 1-2 km thick at a high air temperature of 25-35 ° C. The third condition is the ejection of masses of rain and hail. The fulfillment of this condition leads to a decrease in the flow diameter from the initial value of 5–10 km to 1–2 km and an increase in velocity from 30–40 m/s in the upper part of the mesocyclone to 100–120 m/s in the lower part.
In order to have an idea of the consequences of tornadoes, let us consider the description of the Moscow tornado of 1904.
On June 29, 1904, a strong whirlwind swept over the eastern part of Moscow.
On that day, strong thunderstorm activity was noted in four districts of the Moscow region: in Serpukhov, Podolsky, Moskovsky and Dmitrovsky, almost for 200 km. Thunderstorms with hail and storm were observed, in addition, in the Kaluga, Tula and Yaroslavl regions. Starting from the Serpukhov region, the storm turned into a hurricane. The hurricane intensified in the Podolsk region, where 48 villages were affected and there were casualties. The most terrible devastation was brought by a tornado that arose southeast of Moscow in the area of the village of Besedy. The width of the thunderstorm area in the southern part of the Moskovsky region was determined to be 15 km; here the storm moved from south to north, and the tornado arose in the eastern (right) side of the thunderstorm band.
The tornado caused great destruction on its way. The villages of Ryazantsevo, Kapotnya, Chagino were destroyed; then the hurricane flew into the Lublin grove, uprooted and broke up to 7 hectares of forest, then destroyed the villages of Graivoronovo, Karacharovo and Khokhlovka, entered into eastern part Moscow, destroyed the Annenhof grove in Lefortovo, planted under Tsarina Anna Ioannovna, tore off the roofs of houses in Lefortovo, went to Sokolniki, where he felled a centuries-old forest, went to Losinoostrovskaya, where he destroyed 120 hectares of large forest, and disintegrated in the Mytishchi region. Further, there was no tornado, and only a strong storm was noted. The length of the tornado's path is about 40 km, the width all the time fluctuated from 100 to 700 m.
In appearance, the vortex was a column, wide at the bottom, gradually narrowing in the form of a cone and expanding again in the clouds; in other places, sometimes it took the form of just a black spinning pillar. Many eyewitnesses mistook it for rising black smoke from a fire. In those places where the tornado passed through the Moskva River, it captured so much water that the channel was exposed.
The torn roofs of buildings flew through the air like shreds of paper. Even stone walls were destroyed. Half of the bell tower in Karacharovo has been demolished. The whirlwind was accompanied by a terrible rumble; its destructive work lasted from 30 s to 1-2 min. The crackling of falling trees was drowned out by the roar of the whirlwind.
When the funnel approached, it became completely dark. The darkness was accompanied by a terrible noise, a roar and a whistle. Electrical phenomena of unusual intensity have been recorded. Ball lightning was observed in Sokolniki. The rain and hail were also of extraordinary intensity. Hailstones with a chicken egg were noted repeatedly. Individual hailstones were star-shaped and weighed 400-600 g.
- Actions of the population under threat and during hurricanes, storms and tornadoes.
On the windward side of buildings, windows, doors, attic hatches and ventilation openings are tightly closed. Glasses of windows are pasted over, windows and show-windows are protected by shutters or boards. In order to equalize the internal pressure, doors and windows on the leeward side of buildings are opened.
It is advisable to fix fragile institutions (country houses, sheds, garages, stacks of firewood, toilets), dig in with earth, remove protruding parts or disassemble, crushing the disassembled fragments with heavy stones, logs. It is necessary to remove all things from balconies, loggias, window sills.
It is necessary to take care of preparing electric lamps, kerosene lamps, candles, camping stoves, kerosene stoves and stoves in places of shelter, creating stocks of food and drinking water for 2-3 days, medicines, bedding and clothes.
At home, residents should check the placement and condition of electrical panels, gas and water main taps and, if necessary, be able to shut them off. All family members must be taught the rules of self-rescue and first aid for injuries and concussion.
Radios or TVs must be on at all times.
When informed of the imminent approach of a hurricane or severe storm, residents settlements occupy previously preparatory places in buildings or shelters, best of all in basements and underground structures (but not in the flood zone).
While in the building, you should beware of injuries from broken glass. In case of strong gusts of wind, it is necessary to move away from the windows and take a place in the niches of the walls, doorways or stand close to the wall. For protection, it is also recommended to use built-in wardrobes, durable furniture and mattresses.
When forced to stay in the open air, it is necessary to be away from buildings and occupy ravines, pits, ditches, ditches, road ditches for protection. In this case, you need to lie on the bottom of the shelter and press tightly to the ground, grab the plants with your hands.
Any protective actions reduce the number of injuries caused by the throwing action of hurricanes and storms, and also provide protection from flying fragments of glass, slate, tiles, bricks and various objects. You should also avoid being on bridges, pipelines, in places in close proximity to objects that have highly toxic and flammable substances (chemical, oil refineries and storage bases).
During storms, avoid situations that increase the likelihood of electric shock. Therefore, you can not hide under separate trees, poles, come close to power transmission towers.
During and after a hurricane or storm, it is not recommended to enter susceptible buildings, and if necessary, this should be done with caution, making sure that there are no significant damage to stairs, ceilings and walls, fires, gas leaks, rupture of electrical wires.
During snow or dust storms leaving the premises is allowed in exceptional cases and only as part of a group. At the same time, it is mandatory to inform relatives or neighbors of the route of movement and the time of return. In such conditions, it is allowed to use only pre-prepared vehicles capable of moving with snow, sand drifts, and sleet. If it is impossible to move further, mark the parking lot, completely close the blinds and cover the engine from the side of the radiator.
When receiving information about the approach of a tornado or detecting it by external signs, you should leave all modes of transport and take cover in the nearest basement, shelter, ravine, or lie down on the bottom of any recess and cling to the ground. When choosing a place of protection against a tornado, it should be remembered that this natural phenomenon is often accompanied by heavy rainfall and large hail. In such cases, it is necessary to take measures to protect against damage by these hydrometeorological phenomena.
After the end of the active phase of the disaster, rescue and recovery work begins: dismantling the rubble, searching for the living, the wounded and the dead, providing assistance to those who need it, restoring housing, roads, businesses and a gradual return to normal life.
- Conclusion
I have come to the conclusion that there is a wide variety of such natural disasters. But the most dangerous meteorological phenomena are storms, hurricanes, tornadoes.
Natural emergencies can result in loss of life, damage to human health or the environment. natural environment, significant losses and violation of the living conditions of people.
From the point of view of the possibility of carrying out preventive measures, hazardous natural processes, as a source of emergency situations, can be predicted with a very short lead time.
In recent years, the number of natural disasters has been on the rise. This cannot go unnoticed. The management and bodies of the Ministry of Emergency Situations draw the necessary conclusions from this.
- List of used literature.
etc.................
The results of the interaction of certain atmospheric processes, which are characterized by certain combinations of several meteorological elements, are called atmospheric events.
Atmospheric phenomena include: thunderstorm, blizzard, dusty brown, fog, tornado, polar lights, etc.
All meteorological phenomena observed at meteorological stations are divided into the following groups:
hydrometeors , are a combination of rare and solid or both particles of water suspended in the air (clouds, fogs) that fall in the atmosphere (precipitation); which settle on objects near the earth's surface in the atmosphere (dew, hoarfrost, ice, frost); or raised by the wind from the surface of the earth (blizzard);
lithometeors , are a combination of solid (non-aqueous) particles that are lifted by the wind from the earth's surface and are transported to a certain distance or remain suspended in the air (dust drift, dust storms, etc.);
electrical Phenomena, to which are the manifestations of the action of atmospheric electricity, which we see or hear (lightning, thunder);
optical phenomena in the atmosphere, which arise as a result of reflection, refraction, scattering and diffraction of solar or monthly light (halo, mirage, rainbow, etc.);
unclassified (miscellaneous) phenomena in the atmosphere, which are difficult to attribute to any of the types indicated above (squall, whirlwind, tornado).
Vertical inhomogeneity of the atmosphere. The most important properties of the atmosphere
According to the nature of temperature distribution with height, the atmosphere is divided into several layers: troposphere, stratosphere, mesosphere, thermosphere, exosphere.
Figure 2.3 shows the course of temperature change with distance from the earth's surface in the atmosphere.
А – altitude 0 km, t = 15 0 С; B - height 11 km, t = -56.5 0 С;
C – altitude 46 km, t = 1 0 С; D - height 80 km, t = -88 0 С;
Figure 2.3 - The course of temperature in the atmosphere
Troposphere
The thickness of the troposphere in our latitudes reaches 10-12 km. The main part of the mass of the atmosphere is concentrated in the troposphere, therefore, various weather phenomena are most clearly manifested here. In this layer, there is a continuous decrease in temperature with height. It averages 6 0 C for every 1000 g. The sun's rays strongly heat the earth's surface and the adjacent lower layers of air.
The heat that comes from the earth is absorbed by water vapor, carbon dioxide, dust particles. Above, the air is more rarefied, there is less water vapor in it, and the heat radiated from below has already been absorbed by the lower layers - therefore the air is colder there. Hence the gradual drop in temperature with height. In winter, the surface of the earth is very cold. This is facilitated by the snow cover, which reflects most of the sun's rays and at the same time radiates heat into the higher layers of the atmosphere. Therefore, the air near the surface of the earth is very often colder than at the top. The temperature rises slightly with altitude. This so-called winter inversion (temperature reversal). In the summer, the earth is heated by the sun's rays strongly and unevenly. From the most heated areas rise air streams, whirlwinds. In place of the air that has risen, air flows in from the less heated areas, in turn, being replaced by air that descends from above. Convection occurs, which causes the atmosphere to mix in the vertical direction. Convection destroys fog and reduces dust in the lower atmosphere. Thus, due to vertical movements in the troposphere, there is a constant mixing of air, which ensures the constancy of its composition at all altitudes.
The troposphere is the place where clouds, precipitation and other natural phenomena constantly form. Between the troposphere and the stratosphere there is a thin (1 km) transitional layer called the tropopause.
Stratosphere
The stratosphere extends up to a height of 50-55 km. The stratosphere is characterized by an increase in temperature with height. Up to a height of 35 km, the temperature rises very slowly; above 35 km, the temperature rises rapidly. The increase in air temperature with height in the stratosphere is associated with the absorption of solar radiation by ozone. At the upper boundary of the stratosphere, the temperature fluctuates sharply depending on the time of year and the latitude of the place. The rarefaction of the air in the stratosphere causes the sky there to be almost black. Always in the stratosphere good weather. The sky is cloudless and mother-of-pearl clouds appear only at an altitude of 25-30 km. There is also intensive air circulation in the stratosphere and its vertical movements are observed.
Mesosphere
Above the stratosphere is a layer of the mesosphere, up to approximately 80 km. Here the temperature drops with height to several tens of degrees below zero. Due to the rapid drop in temperature with height, there is highly developed turbulence in the mesosphere. At altitudes close to the upper boundary of the mesosphere (75-90 km), noctilucent clouds are observed. It is most likely that they are composed of ice crystals. At the upper boundary of the mesosphere, the air pressure is 200 times less than at the earth's surface. Thus, in the troposphere, stratosphere and mesosphere together, up to a height of 80 km, there is more than 99.5% of the total mass of the atmosphere. The higher layers have a small amount of air.
Thermosphere
The upper part of the atmosphere, above the mesosphere, is characterized by very high temperatures and is therefore called the thermosphere. It differs, however, in two parts: the ionosphere, which extends from the mesosphere to heights of about a thousand kilometers, and the exosphere, which is located above it. The exosphere passes into the earth's corona.
The temperature here increases and reaches + 1600 0 C at an altitude of 500-600 km. Gases are very rarefied here, molecules rarely collide with each other.
The air in the ionosphere is extremely rarefied. At altitudes of 300-750 km, its average density is about 10 -8 -10 -10 g/m 3 . But even with such a low density of 1 cm 3, air at an altitude of 300 km still contains about one billion molecules or atoms, and at an altitude of 600 km - over 10 million. This is several orders of magnitude greater than the content of gases in interplanetary space.
The ionosphere, as the name itself says, is characterized by a very strong degree of air ionization - the content of ions here is many times greater than in the lower layers, despite the large overall rarefaction of the air. These ions are mainly charged oxygen atoms, charged nitrogen oxide molecules, and free electrons.
In the ionosphere, several layers or regions with maximum ionization are distinguished, especially at altitudes of 100-120 km (layer E) and 200-400 km (layer F). But even in the intervals between these layers, the degree of ionization of the atmosphere remains very high. The position of the ionospheric layers and the concentration of ions in them change all the time. The concentration of electrons in a particularly high concentration is called electron clouds.
The electrical conductivity of the atmosphere depends on the degree of ionization. Therefore, in the ionosphere, the electrical conductivity of air is generally 10-12 times greater than that of the earth's surface. Radio waves undergo absorption, refraction and reflection in the ionosphere. Waves longer than 20 m cannot pass through the ionosphere at all: they are reflected by electron clouds in the lower part of the ionosphere (at altitudes of 70-80 km). Medium and short waves are reflected by the higher ionospheric layers.
It is due to reflection from the ionosphere that long-range communication at short waves is possible. Multiple reflection from the ionosphere and the earth's surface allows short waves to zigzag to propagate over long distances, bending around the surface globe. Since the position and concentration of the ionospheric layers are constantly changing, the conditions for absorption, reflection and propagation of radio waves also change. Therefore, reliable radio communication requires continuous study of the state of the ionosphere. Observation of the propagation of radio waves is the means for such research.
In the ionosphere, auroras and a glow of the night sky close to them in nature are observed - a constant luminescence of atmospheric air, as well as sharp fluctuations magnetic field- ionospheric magnetic storms.
Ionization in the ionosphere takes place under the influence of ultraviolet radiation from the sun. Its absorption by molecules of atmospheric gases leads to the appearance of charged atoms and free electrons. Fluctuations in the magnetic field in the ionosphere and auroras depend on fluctuations in solar activity. Changes in the flux of corpuscular radiation that goes from the Sun into the Earth's atmosphere are associated with changes in solar activity. Namely, corpuscular radiation is of fundamental importance for these ionospheric phenomena. The temperature in the ionosphere increases with altitude up to very large values. At altitudes close to 800 km, it reaches 1000°.
Speaking of high temperatures ionosphere, mean that particles of atmospheric gases move there at very high speeds. However, the density of air in the ionosphere is so low that a body that is in the ionosphere, such as a satellite, will not be heated by heat exchange with air. The temperature regime of the satellite will depend on the direct absorption of solar radiation by it and on the return of its own radiation to the surrounding space.
Exosphere
Atmospheric layers above 800-1000 km are distinguished by the name of the exosphere (outer atmosphere). The velocities of gas particles, especially light ones, are very high here, and due to the extremely rarefied air at these heights, particles can circle the Earth in elliptical orbits without colliding with each other. In this case, individual particles can have velocities sufficient to overcome the force of gravity. For uncharged particles, the critical speed will be 11.2 km/s. Such particularly fast particles can, moving along hyperbolic trajectories, fly out of the atmosphere into outer space, "slip out", and dissipate. Therefore, the exosphere is also called the scattering sphere. Hydrogen atoms are predominantly susceptible to slipping.
It has recently been assumed that the exosphere, and with it in general earth atmosphere, ends at altitudes of the order of 2000-3000 km. But observations from rockets and satellites have shown that hydrogen that slips out of the exosphere forms a so-called terrestrial corona around the Earth, which extends to more than 20,000 km. Of course, the density of gas in the Earth's corona is negligible.
With the help of satellites and geophysical rockets, the existence of the Earth's radiation belt in the upper part of the atmosphere and near-Earth space, which begins at an altitude of several hundred kilometers and extends tens of thousands of kilometers from the earth's surface, has been established. This belt consists of electrically charged particles - protons and electrons, captured by the Earth's magnetic field, which move at very high speeds. The radiation belt constantly loses particles in the earth's atmosphere and is replenished by fluxes of solar corpuscular radiation.
The composition of the atmosphere is divided into homosphere and heterosphere.
The homosphere extends from the earth's surface to a height of about 100 km. In this layer, the percentage of the main gases does not change with height. The molecular weight of air also remains constant.
The heterosphere is located above 100 km. Here oxygen and nitrogen are in the atomic state. The molecular weight of air decreases with height.
Does the atmosphere have an upper boundary? The atmosphere has no boundaries, and, gradually rarefied, passes into interplanetary space.
