Fortunately, few residents of our country know what a tornado is. Of course, we do not mean the small turbulence that sometimes occurs in fields and deserted roads. It's about about giant atmospheric vortices, which, as a rule, appear in a thundercloud and descend almost to the very earth's surface in the form of a trunk or cloud sleeve with a diameter of several tens or even hundreds of meters. Despite the fact that they do not exist for long, a lot of trouble can be expected from them. Let's take a closer look at what this phenomenon is.
What is a tornado?
Try to imagine the huge air funnel, which spins at incredible speed and at the same time draws everything that happens to be nearby into its center. In America, many people know firsthand what a tornado is. There this phenomenon is usually called a tornado. There are also synonyms: meso-hurricane and thrombus, but they are used much less frequently. The rotation inside such a vortex goes counterclockwise, similar to what happens in cyclones that arise in the northern hemisphere of our planet.
Characteristics of a tornado
Vertically, one such funnel can reach ten, and vertically - fifty kilometers. it often exceeds 33 m/s. When talking about what a tornado is, it should be noted that it has incredible power. According to experts such as A. Yu. Gubar, S. A. Arsenyev and V. N. Nikolaevsky, the energy of an average tornado with a radius of a kilometer and a speed of about 70 m/s is comparable to the energy atomic bomb, tested by the United States in July 1945 in New Mexico. In their shape, tornadoes are not only in the form of funnels. Sometimes a tornado resembles a barrel, a cone, a glass, a whip-like rope, a column, devil's horns, etc. But most often it appears in the form of a pipe, funnel or trunk that hangs from the mother cloud. Take a look at the tornado, photographed below. Looks scary, doesn't it?
Sometimes the number of victims of such phenomena reaches several hundred people. Tristate is considered the most terrible and famous tornado in the entire history of America. Having swept through the territory of three Illinois, Indiana on March 18, 1925, he took with him 747 human lives…
Where does a tornado appear and what causes it?
Tornadoes often form on tropospheric fronts, where there are interfaces with different temperatures, speeds and air humidity. In the zone of collision between cold and warm, it is extremely unstable and contributes to the formation of a tornado in the mother cloud, and below several smaller turbulent vortices. Most often this happens in autumn and spring-summer. For example, cold fronts separate dry, cold air from Canada from moist, warm air from Atlantic Ocean or Sometimes such a collision occurs over sea surface, and then a sea tornado appears.
It can be almost completely transparent and only from the lower part, dusty with water, can one guess about the danger threatening the ship. Tornadoes happen not only on Earth, but also on other planets of our system, for example, on Jupiter and Neptune. A tornado cannot appear on Mars due to low pressure and too thin an atmosphere. But on Venus the situation is exactly the opposite, and therefore the probability of tornadoes appearing there is very high.
A tornado (synonyms - tornado, thrombus, meso-hurricane) is a strong whirlwind that forms in hot weather under a well-developed cumulonimbus cloud and spreads to the surface of the earth or reservoir in the form of a giant dark rotating column or funnel.
The vortex has a vertical (or slightly inclined to the horizon) axis of rotation, the height of the vortex is hundreds of meters (in some cases 1-2 km), the diameter is 10-30 m, the lifetime is from several minutes to an hour or more.
The tornado passes through a narrow strip, so there may not be a significant increase in wind directly at the weather station, but in fact inside the tornado the wind speed reaches 20-30 m/s or more. A tornado is most often accompanied by heavy rain and thunderstorms, sometimes hail.
There is very low pressure in the center of the tornado, as a result of which it sucks into itself everything that it encounters on its way and can lift water, soil, individual items, buildings, sometimes moving them over considerable distances.
Possibilities and methods of forecasting
A tornado is a phenomenon that is difficult to predict. The tornado monitoring system is based on a system of visual observations by a network of stations and posts, which practically allows only the azimuth of the tornado’s movement to be determined.
By technical means Weather radars are sometimes used to detect tornadoes. However, conventional radar is not able to detect the presence of a tornado because the size of the tornado is too small. Cases of tornadoes being detected by conventional radars were noted only very close range. Radar can be of great help when tracking a tornado.
When the radio echo of a cloud associated with a tornado can be identified on the radar screen, it becomes possible to warn about the approach of a tornado one to two hours in advance.
Doppler radars are used in the operational work of a number of meteorological services.
Protection of the population during hurricanes, storms, tornadoes
In terms of the speed of spread of danger, hurricanes, storms and tornadoes can be classified as emergency events with a moderate speed of spread, which makes it possible to carry out a wide range of preventive measures both in the period preceding the immediate threat of occurrence and after their occurrence - until the moment of direct impact.
These time-based measures are divided into two groups: advance (preventive) measures and work; operational protective measures carried out after the announcement poor prognosis, immediately before a given hurricane (storm, tornado).
Advance (preventive) measures and work are carried out in order to prevent significant damage long before the onset of the impact of a hurricane, storm and tornado and can cover a long period of time.
Advance measures include: restrictions on land use in areas prone to hurricanes, storms and tornadoes; restrictions on the location of hazardous production facilities; dismantling of some outdated or fragile buildings and structures; strengthening industrial, residential and other buildings and structures; carrying out engineering and technical measures to reduce the risk of hazardous industries in strong wind, incl. promotion physical stamina storage facilities and equipment containing flammable and other hazardous substances; creation of material and technical reserves; training of the population and rescue personnel.
Protective measures carried out after receiving a storm warning include: forecasting the path and time of approach to various areas of a hurricane (storm, tornado), as well as its consequences; promptly increasing the size of the material and technical reserve necessary to eliminate the consequences of a hurricane (storm, tornado); partial evacuation of the population; preparation of shelters, basements and other buried premises to protect the population; moving unique and especially valuable property into durable or recessed premises; preparation for restoration work and life support measures for the population.
Tornadoes are not frequent in Russia. The most famous are the Moscow tornadoes of 1904. Then on June 29, several craters descended from a thundercloud over the outskirts of Moscow, destroying large number buildings - both urban and rural. Tornadoes were accompanied by thunderstorm phenomena - darkness, thunder and lightning.
The material was prepared based on information from open sources
Description
Inside the funnel, the air descends and outside it rises, rotating rapidly, creating an area of very rarefied air. The vacuum is so significant that closed gas-filled objects, including buildings, can explode from the inside due to the pressure difference. This phenomenon increases the destruction from the tornado and makes it difficult to determine its parameters. Determining the speed of air movement in a funnel is still a matter of serious problem. Basically, estimates of this quantity are known from indirect observations. Depending on the intensity of the vortex, the speed of the flow in it can vary. It is believed that it exceeds 18 m/s and can, according to some indirect estimates, reach 1300 km/h. The tornado itself moves along with the cloud that generates it. This movement can produce speeds of tens of km/h, usually 20-60 km/h. According to indirect estimates, the energy of an ordinary tornado with a radius of 1 km and an average speed of 70 m/s is comparable to the energy of a standard atomic bomb, similar to the one that was exploded in the United States during the Trinity tests in New Mexico on July 16, 1945. (unavailable link) The record for the lifetime of a tornado can be considered the Mattoon tornado, which on May 26, 1917, covered 500 km across the United States in 7 hours and 20 minutes, killing 110 people. The width of the vague funnel of this tornado was 0.4-1 km; a whip-like funnel was visible inside it. To others famous case The tornado is the Tristate tornado, which passed through the states of Missouri, Illinois and Indiana on March 18, 1925, traveling 350 km in 3.5 hours. The diameter of its vague crater ranged from 800 m to 1.6 km.
In the Northern Hemisphere, air rotation in tornadoes usually occurs counterclockwise. This may be due to the directions of mutual movements of air masses on either side of the atmospheric front on which the tornado is formed. Cases of reverse rotation are also known. In areas adjacent to the tornado, air descends, causing the vortex to close.
At the point of contact of the base of the tornado funnel with the surface of the earth or water, a cascade- a cloud or column of dust, debris and objects raised from the ground or water splashes. When a tornado is formed, the observer sees how a cascade rises from the ground towards the funnel descending from the sky, which then covers the lower part of the funnel. The term comes from the fact that the debris, having risen to a certain insignificant height, can no longer be held by the air flow and falls to the ground. The funnel, without touching the ground, can envelop case. Merging, the cascade, the case and the mother cloud create the illusion of a tornado funnel that is wider than it actually is.
Sometimes a whirlwind formed at sea is called a tornado, and on land - a tornado. Atmospheric vortices, similar to tornadoes, but formed in Europe, are called blood clots. But more often all these three concepts are considered synonyms.
Reasons for education
The reasons for the formation of tornadoes have not yet been fully studied. It is possible to indicate only a few general information, most characteristic of typical tornadoes.
Tornadoes go through three main stages in their development. At the initial stage, an initial funnel appears from a thundercloud, hanging above the ground. Cold layers of air located directly under the cloud rush down to replace warm ones, which, in turn, rise upward (such unstable system usually formed by the connection of two atmospheric fronts - warm and cold). The potential energy of this system is converted into kinetic energy of the rotational movement of air. The speed of this movement increases, and it takes on its classic appearance.
The rotational speed increases over time, while in the center of the tornado the air begins to rise intensively. This is how the second stage of a tornado’s existence proceeds - the stage of a formed vortex of maximum power. The tornado is fully formed and moves in different directions.
The final stage is the destruction of the vortex. The power of the tornado weakens, the funnel narrows and breaks away from the surface of the earth, gradually rising back into the mother cloud.
The lifetime of each stage is different and ranges from several minutes to several hours (in exceptional cases). The speed of tornadoes also varies, on average - 40 - 60 km/h (in very rare cases it can reach 210 km/h).
Places of tornado formation
Places where tornadoes can form are orange on the map.
The second region of the globe where conditions for the formation of tornadoes arise is Europe (except for the Iberian Peninsula), and the entire European territory of Russia, with the exception of the south of Russia, Karelia and the Murmansk region, as well as other northern regions.
Thus, tornadoes are mainly observed in the temperate zone of both hemispheres, from approximately the 60th parallel to the 45th parallel in Europe and the 30th parallel in the USA.
Tornadoes are also recorded in the east of Argentina, South Africa, the west and east of Australia and a number of other regions, where there may also be conditions for collision of atmospheric fronts.
Classification of tornadoes
Scourge-like
This is the most common type of tornado. The funnel looks smooth, thin, and can be quite tortuous. The length of the funnel significantly exceeds its radius. Weak tornadoes and funnels that descend into the water are usually whiplash-like tornadoes.
Vague
They look like shaggy, rotating clouds that reach the ground. Sometimes the diameter of such a tornado even exceeds its height. All large diameter craters (more than 0.5 km) are vague. Usually these are very powerful vortices, often composite. They cause enormous damage due to their large size and very high wind speeds.
Composite
May consist of two or more separate blood clots around a main central tornado. Such tornadoes can be of almost any power, however, most often they are very powerful tornadoes. They cause significant damage over large areas. .
Fiery
These are ordinary tornadoes generated by a cloud formed as a result of a strong fire or volcanic eruption. It was precisely such tornadoes that were first artificially created by man (experiments by J. Dessens in the Sahara, which continued in 1960-1962). They “absorb” tongues of flame that stretch towards the mother cloud, forming a fiery tornado. A fire can spread tens of kilometers. They can be whip-like. Cannot be fuzzy (the fire is not under pressure, like in whiplash-like tornadoes.
Water
These are tornadoes that formed over the surface of oceans, seas, and in rare cases, lakes. They “absorb” water (why? See above) and form waterspouts. They “absorb” waves and water, forming, in some cases, whirlpools that stretch towards the mother cloud, forming a waterspout. They can be whip-like. Cannot be fuzzy (like fire tornadoes: the water is not under pressure, like a whip-like tornado).
Earthen
These tornadoes are very rare, formed during destructive cataclysms or landslides, sometimes earthquakes above 7 points on the Richter scale, very high pressure drops, and very thin air. A whip-like tornado, located with a “carrot” with its thick part towards the ground, inside a dense funnel, a thin stream of earth inside, a “second shell” of earthen slurry (if there is a landslide). In the case of earthquakes, it lifts stones, which is very dangerous.
Ball
It is not yet known how it is “structured”. It has not yet been proven that it exists. It can be fire, water, earth, air, and, most dangerously, gas, which causes explosions, like ball lightning. In general, this is a voluminous oval or ball that spins at breakneck speed, then flattens out, flattening all its contents (if a person gets in there, it will look like a thick pancake, or torn into pieces). I was in Brazil during a fire tornado, but due to its small size (they are about 10 - 50 meters in diameter) they did not notice it.
Snowy
These are snow tornadoes during a severe snowstorm.
Sand whirlwinds
Sand whirlwinds
It is necessary to distinguish from the considered tornadoes the sand “tornadoes” (“dust devils”) observed in deserts (Egypt, Sahara); Unlike the previous ones, the latter are sometimes called thermal vortices. Similar in appearance to real tornadoes, desert sand whirlwinds have nothing in common with the former either in size, origin, structure or action. Arising under the influence of local heating of the sandy surface sun rays, sand vortices are a real cyclone (barometric minimum) in miniature. A decrease in air pressure under the influence of heating, causing an influx of air from the sides to the heated place, under the influence of the rotation of the Earth, and even more so - the incomplete symmetry of such an upward flow, forms a rotation that gradually grows into a funnel and sometimes, when favorable conditions, taking on quite impressive dimensions. Carried away by the vortex movement, the masses of sand are lifted by an upward movement in the center of the vortex into the air, and thus a sand column is created, which resembles a tornado. In Egypt, such sand whirlwinds up to 500 and even 1000 meters high with a diameter of up to 2-3 meters were observed. When there is wind, these vortices can move, carried away by the general movement of air. After holding on for some time (sometimes up to 2 hours), such a vortex gradually weakens and crumbles.
Damaging factors
Tornado Precautions
It is necessary to take shelter in the strongest reinforced concrete structure with a steel frame, keeping close to the strongest wall, also - best option shelter - an underground shelter or cave. Staying in a car or trailer, given the high lifting force of a tornado, is mortally dangerous; it is also life-threatening to encounter the elements outdoors.
If a tornado finds a person in an open space, then you need to move with maximum speed perpendicular visible movement funnels. Or, if retreat is impossible, take cover in depressions on the surface (ravines, holes, trenches, road ditches, ditches, ditches) and press yourself tightly to the ground, face down, covering your head with your hands. This will help significantly reduce the likelihood and severity of injuries from objects and debris carried by the tornado.
In a small one- or two-story private house, you can use the basement (here, for such an emergency, it is wise to place a supply of water and canned food, as well as candles or LED lamps in advance), if there is no basement, then you should stay in the bathroom or in the center of a small room on the bottom floor, perhaps under durable furniture, but away from windows. It would be prudent to dress in thick clothes, taking money and documents with you. To prevent the house from exploding from the pressure drop caused by the injection of air by a whirlwind, it is recommended to tightly close all windows and doors from the approaching tornado, and opposite side- open wide and secure. According to safety precautions, it is advisable to turn off the gas and turn off the electricity.
Interesting facts from the chronicle of tornadoes
Current Research
Literature
- Varaksin A. Yu., Romash M. E., Kopeytsev V. N. Tornado. - M.: Fizmatlit, 2011. - 344 p. - 300 copies. - ISBN 978-5-9221-1249-9
Notes
- Soviet encyclopedic dictionary. - M.: “ Soviet Encyclopedia", 1981. - 1600 p.
- Nalivkin D.V. Tornadoes. - M.: Nauka, 1984. - 111 p.
- "Smerch" // Etymological dictionary Russian language. / comp. M. R. Vasmer, - M.: Progress 1964-1973
- S.P. Khromov, M.A. Petrosyants. Small-scale eddies. Meteorology and climatology. Archived from the original on August 23, 2011. Retrieved June 8, 2009.
- (unavailable link)
- Mezentsev V. A., “Unsolved Earth: stories about how our planet was discovered and continues to be discovered” / reviewer - Dr. geogr. Sciences E. M. Murzaev, - M.: Mysl, 1983, P. 136-142
- G. Lyuboslavsky: // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional ones). - St. Petersburg. , 1890-1907.
- Chernysh I. V., “Traveler's Hiking Encyclopedia”, - M.: FAIR-PRESS, 2006, P. 289, ISBN 5-8183-0982-7
- John Wiseman « Complete Guide on survival", - M.: AST, 2011, P. 549, ISBN 978-5-17-045760-1
- Konstantin Ranks“Desert Russia”, - M.: Eksmo, 2011, pp. 185-187, ISBN 978-5-699-46249-0
- Kravchuk P. A. Records of nature. - L.: Erudite, 1993. - 216 p. - 60,000 copies. - ISBN 5-7707-2044-1
- (English) National Severe Storms Laboratory VORTEX: Unraveling the Secrets. National Oceanic and Atmospheric Administration (October 30, 2006). Archived from the original on November 4, 2012.
- (English) Michael H Mogil Extreme Weather. - New York: Black Dog & Leventhal Publisher, 2007. - P. 210–211. - ISBN 978-1-57912-743-5
- (English) Kevin McGrath Mesocyclone Climatology Project. University of Oklahoma (November 5, 1998). Archived from the original on November 4, 2012. Retrieved November 19, 2009.
- (English) Seymour, Simon (2001). Tornadoes. New York City, New York: HarperCollins. p. 32. ISBN 978-0-06-443791-2.
See also
Links
- Tornado in Krasnogorsk on August 3, 2007 - meteorological data and video on the website Meteoweb.ru, 07/19/2008.
In fact, many of the disasters we may face are caused by natural phenomena and human will.
Fear and superstition aside, humans are faced with one of the most amazing sights in the natural world. These twisting storm columns can reach wind speeds of up to 200 mph, destroying homes and buildings in the process and are called tornadoes or waterspouts.
However, in some parts of the world, these powerful tornadoes are a common occurrence. The United States alone experiences more than 1,000 such natural events per year, and tornadoes are reported on every continent except Antarctica. maybe these natural phenomena.
What is a tornado
The natural phenomenon of a tornado is a violently rotating column of air that descends with a thunderstorm to the ground. No other weather phenomenon can match the fury and destructive force. This natural phenomenon can be strong enough to destroy large buildings, leaving only a bare concrete foundation. In addition, they can lift 20-ton railway cars from their tracks, and turn ordinary cars into flying ones.
A tornado is a truly complex natural phenomenon and does not even provide an explanation. They form only if the storm begins to spin vertically, a corkscrew of air rising high into the sky. Scientists believe the rotation begins due to wind shear, rapid changes in wind speed or direction across different levels atmosphere.
Imagine a piece of plasticine between your hands. If you move this plasticine in opposite directions, it rises into a tube between your hands. 
Difference between hurricane, tornado and tornado
The natural phenomenon of a tornado is a rapidly rotating column of air that extends from a thunderstorm cumulonimbus cloud to the ground. The natural phenomenon is often (but not always) visible as a funnel cloud. It is important to never confuse it with a hurricane or other tropical cyclone because tornadoes and hurricanes are very different natural phenomena. Perhaps the only similarity between them is that they both contain strong rotating winds that can cause damage.
If hurricanes nuclear warhead nature, then the tornado is its smart bomb.
There is no difference between a tornado and a tornado, since tornado is a translation into Russian.
However, there are many differences between tornadoes and hurricanes. A large tornado is observed up to 4 km wide, and most< 0.8 км в ширину. Материнские storm clouds, which form this phenomenon, are usually about 16 km wide. However, hurricanes tend to be much larger, ranging from approximately 160 km to 1600 km in width. 
The life of a tornado is short, from a few seconds to several hours. Against, life cycle A hurricane can last from several days to several weeks. Storm clouds The systems that produce them require strong vertical wind shear and strong horizontal temperature changes. Hurricanes thrive in regions where there is weak vertical wind shear and little horizontal change in atmospheric temperature. Additionally, violent tornadoes usually occur over land, while hurricanes almost always form over the ocean.
Finally, the most powerful tornadoes can have wind speeds of more than 300 km/h, but even the most powerful hurricanes rarely produce wind speeds of more than 250 km/h.
Isolated storm clouds can produce tornadoes as the hurricane makes landfall, in some cases within days of landfall. The tornado is most likely to occur in a specific quadrant of the hurricane. Some studies show that the selected quadrant most often represents the front right quadrant with respect to the direction of hurricane propagation, but other studies show that the northeast quadrant is favored for the occurrence of the event regardless of the direction of hurricane propagation. Despite this, a tornado usually forms in the part of the hurricane where the vertical wind shear is greatest. If the hurricane interacts with the front or it absorbs unstable air, development will become more favorable. Some hurricanes may not produce tornadoes, while others develop somewhat affecting the Earth.
In general, tornadoes associated with hurricanes are relatively weak and short-lived, especially compared to those that occur in the plains of the United States. However, the effects of this natural phenomenon, added to the effects of hurricane-force winds, can cause enormous destruction.
Where do tornadoes most often occur?
This natural phenomenon occurs most often in the United States when warm, moist winds move north from the Gulf of Mexico during the spring and summer, where they meet cold, dry southern Canadian fronts.
In spring and summer months Southern winds predominate on the plains. At the origins of these southern winds lie warm waters Gulf of Mexico, which provide a lot of warm, moist air necessary for intense thunderstorm development. Hot dry air forms over more high altitudes to the west and becomes a lid as it spreads east over the humid air of the Gulf. Dry air and Gulf air meet near land where a boundary known as the dry line forms west of Oklahoma.
Tornadoes are the most powerful tornadoes in nature. On average, 800 tornadoes are reported annually, resulting in approximately 80 deaths and 1,500 injuries. It is a global phenomenon, affecting people on every continent except Antarctica. 
How do tornadoes form?
The truth is that scientists don't fully understand how they form. Typically, tornadoes develop several thousand meters above the surface of the earth within a huge rotating thundercloud. This thunderstorm contains a very strong rotating updraft. It is this rotation that drags everything along the way.
A tornado begins as a funnel cloud extending from thunderclouds. The cloud funnel becomes visible due to water droplets, but in some cases may appear invisible due to lack of moisture. When the funnel cloud is halfway between the base and the ground, a "tornado" begins.
High-speed winds swirl around a small, relatively calm center and suck up dust and debris, making this natural phenomenon darker and more visible.
What is the path length of a tornado? How long will they last? How fast do they move?
The trajectories of this natural phenomenon vary from 100 meters to 4 kilometers in width and rarely exceed 20 kilometers in length. They can last from a few seconds to more than an hour, but most do not exceed 10 minutes. Most travel from southwest to northeast at an average speed of 50 km per hour, but speeds range from almost no traffic to 100 km per hour.
When and where do tornadoes occur?
Most tornadoes occur in the relatively flat basin between the mountain and the sea, but no state is immune. Peak months for the phenomenon are April, May and June. The typical onset time is a fairly warm and sultry spring afternoon and 9 pm.
What causes a tornado?
A tornado forms under a specific set of weather conditions in which three very different types air combine in a certain way. There is a layer of warm and moist air near the ground, along with strong southerly winds. Colder air and strong westerly or southwesterly winds lie in upper atmosphere. Changes in temperature and humidity between the surface and upper levels create what we call instability. It is a necessary ingredient for the formation of a natural phenomenon. A third layer of hot, dry air is established between the warm, moist air at low levels and the cool, dry air. This hot layer acts as a lid and allows the warm air to become even more unstable. Complex interactions between the updraft and surrounding winds can cause the updraft to begin to rotate and the natural phenomenon of a tornado is born.
What is the Fujita Damage Scale?
Dr. Theodore Fujita, who studied this phenomenon, developed a damage scale to provide force ratings based on damage surveys. Since it is very difficult to make direct measurements, damage-based wind estimates are the best way to classify them. The new, improved scale addresses some of the limitations that meteorologists and engineers identified with the introduction of the Fujita scale in 1971. The range of intensities remains as before, from zero to five, with "EF0" being the weakest, associated with very little damage, and "EF5" representing complete destruction, which occurred in Greensburg, Kansas, on May 4, 2007, classified like "EF5". The EF scale was adopted on February 1, 2007.
Constant vigilance and rapid warning have crucial, as this natural phenomenon can strike almost anywhere at any time. Most tornadoes, while violent at the start, are short-lived and often disappear into the rain or darkness. The best way coping with them is willingness. 
What was the largest tornado in the world?
The largest tornado in the world occurred on March 18, 1925 in the USA. 747 people were killed and 2,027 injured in Missouri, Illinois and Indiana when several twisters occurred that day. The largest of these tornadoes, called the "tri-state", took 695 lives and was classified as an F5. He moved 300 km on the ground at a speed of 100 km per hour. This continued on the ground for 7 hours and 20 minutes.
What are the strongest winds?
Using radar, meteorologists recorded that on May 3, 1999, one Twister had winds of 480 km per hour at an altitude of 30 meters. Scientists have found that the strongest winds typically occur around 100 meters above the ground. However, most of this natural phenomenon does not have wind speeds exceeding 150 km per hour.
Although they can occur at any time of the day or night, most tornadoes form late in the day. By this time, the sun had warmed the earth and atmosphere enough to produce thunderstorms.
Introduction
1. The nature of tornadoes and tornadoes
2. The concept of a tornado
3. Rules of conduct when a tornado is approaching
4. Types of tornadoes
5. How tornadoes form
6. Conditions for the formation of tornadoes
7. Why do tornadoes occur?
8. Rules for naming hurricanes, tornadoes and typhoons
9. What's inside a tornado
Conclusion
List of used literature
Introduction
History has preserved a lot of information about natural disasters, which are currently called tropical cyclones and which mainly form over the oceans in the tropics, regularly hitting the eastern and equatorial regions of the continents. Tropical cyclones are hurricanes and typhoons that occur in the northern and southern parts Pacific Ocean, in the Bay of Bengal and the Arabian Sea, in the southern part Indian Ocean, off the coast of Madagascar and the northwestern coast of Australia. Tropical cyclones are usually given names.
One of the insidious and unexpectedly occurring natural formations in the atmosphere is a tornado (tornado). It is a rotating funnel cloud that extends from the base of the thundercloud to the surface of the earth. Typical wind speeds in a tornado are 65–120 km/h, but sometimes this value reaches 320 km/h or more. External sign the approaching tornado makes a noise similar to the roar of a moving freight train. The occurrence of tornadoes is associated with a combination of natural processes, but since the times of the Egyptian pharaohs, tornadoes of artificial origin have been known, which were created over the tops of the pyramids and marked the ascension of the pharaoh’s spirit into the sky to the Sun God “Ra”. The sketches of tornadoes preserved in Egyptian hieroglyphs do not explain the technique of their formation.
The most typical region where tornadoes occur quite often is the United States. Although tornadoes are observed all over the globe. In the United States for the period from 1961 to 2004. Tornadoes killed an average of 83 people per year. Tornadoes occur most often in the eastern states adjacent to the Gulf of Mexico, with their frequency peaking in February and March. In the states of Iowa and Kansas, the highest frequency of tornadoes occurs in May–June. The average number of tornadoes in the United States is estimated at about 800 per year, of which 50% occur in April–June. The territorial heterogeneity of the frequency of tornadoes in the United States has stable characteristics: in the state of Texas – 120 tornadoes/year, and in the northeastern and western states– 1 tornado/year. For example, in April and November 2002 alone, more than 100 tornadoes tore through the United States, leaving widespread destruction and causing more than 600 insurance claims. The elements do not leave other countries alone either. For example, the 2002 winter hurricane Jeanette, which swept through Europe, caused widespread destruction and resulted in insurance claims of over $1 billion.
1. The nature of tornadoes and tornadoes
Tornadoes and tornadoes are small-scale atmospheric vortices. The nature of the occurrence of these atmospheric phenomena is similar to the nature of the occurrence of tropical cyclones. Tornadoes and tornadoes have similar structures.
Let's consider how tornadoes and tornadoes arise.
From the center of a thundercloud, the lower part of which takes the peculiar shape of an overturned funnel, a huge dark “trunk” gradually descends, stretching towards the surface of the sea or land. Here, a wide funnel consisting of water and dust rises towards this phenomenon. The “trunk” plunges its end into the open bowl of the resulting funnel. A solid column appears that can move at speeds of up to 40 km/h. The height of the pillar can reach from eight hundred meters to one and a half kilometers. From a powerful thundercloud, not one, but several tornado funnels can descend at once, each of which usually causes enormous damage.
The movement of air in the system of tornadoes and tornadoes occurs counterclockwise. But sometimes it happens that the air moves clockwise. At the same time, air rises in the form of a spiral. In adjacent areas, air may descend and thus the vortex closes. Under the influence of enormous rotation speed, a centrifugal force, which helps to lower the pressure in it. This leads to the fact that during the movement of the vortex, everything that comes along the way is sucked into it.
2. The concept of a tornado
A tornado is a rapidly rotating column of air descending from or forming beneath a cumulonimbus cloud, often (but not always) visible as a funnel cloud. To be classified as a tornado, the twister must originate from a cloud and touch the ground. It is known that a tornado can create an invisible funnel.
How do tornadoes form in the USA?
The classic answer to this question is that warm, moist air from the Gulf of Mexico collides with cold air from Canada and dry air from the Rocky Mountains across the United States. Under such conditions, a large number of thunderstorms occur, which carry the threat of tornadoes. The most destructive and deadly tornadoes are formed under huge cumulonimbus clouds, which in the USA are called supersells, these clouds rotate, forming mesocyclones. These clouds often bring large hail, squally winds, severe thunderstorms and downpours, as well as tornadoes.
How many tornadoes occur in the US each year?
About a thousand tornadoes occur in the United States every year. It is difficult to say exactly, since some tornadoes occur in sparsely populated areas and therefore are not recorded.
What time of year does the most tornadoes occur?
Generally, tornado season lasts from early spring to mid-summer. In some states, tornadoes peak in May, in others in June or even July. But in general, tornadoes can occur at any time of the year.
What is Tornado Alley?
This historical name central American states, where the largest number of tornadoes are observed. However, tornadoes can occur anywhere: both in the West and in the east coast USA, as well as in Canada and other countries.
How long does a tornado last?
A tornado can last from a few minutes to an hour or more. But most of them last no more than ten minutes.
How are tornadoes in the northern hemisphere different from those in the southern hemisphere? They differ in the direction of rotation. Most tornadoes (but not all!) have a cyclonic rotation, that is, counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. Anticyclonic tornadoes rotate clockwise in the northern hemisphere. They most often occur in the form of waterspouts, and there are also many cases of simultaneous observation of cyclonic and anticyclonic tornadoes under the same thunderstorm.
3. Rules of conduct when a tornado is approaching
A tornado is a strong atmospheric whirlwind over land, characterized by exceptionally high frequency of occurrence.
Tornadoes occur quite often, but it is impossible to predict exactly where they will occur next time, and therefore you have to “chase” a tornado. The mobile laboratories used in such pursuits are too fragile and are destroyed before they can reach the center of the tornado and begin to study it.
It has also not yet been possible to produce a tornado in a laboratory under controlled conditions: this would require an experimental setup hundreds of meters in size.
Tornadoes still remain a poorly understood atmospheric phenomenon, surrounded by many myths and misconceptions.
Usually, when a tornado hits, there is time to take shelter from the storm. In fact, it is not always possible to guess that a real hurricane has arrived, since it can begin with hail or heavy rain. In a wooded area, in the mountains or in a city, danger is often noticed precisely when it is already inevitable. It's also important to know that some tornadoes don't have the typical plume-like appearance of a cloud. The arrival of a tornado is accompanied by strong winds, carrying debris of everything that comes their way.
My car can go much faster than a tornado. In fact, average speed tornadoes travel at 40-65 km/h, and some travel at even higher speeds. Even though your car may be moving faster than the tornado, that doesn't mean you should continue on your way because the tornado moves in a variety of directions. If you are on the road and see a tornado heading in your direction, move out of its path and find shelter.
If there is no other way to hide, then a car will be a more reliable shelter than a trailer or a country house. In fact, this is not always the case. This topic is hotly debated in North America. If you have time, you can jump into a car and take refuge there. In the case of a low-power tornado, the car will serve as a reliable shelter from objects carried by the wind or rolling along the ground. It's best to buckle up well and bend your head as low as possible. However, do not forget that a stronger tornado can destroy cars in its path.
The approach of a tornado can be known early enough to warn the public, thanks to Doppler radar. Doppler radar detects the precipitation and wind that accompany a storm and allows meteorologists to detect signs of an approaching tornado. But the approach of a tornado can only be said with certainty when the tornado is in sight. If weather services warn that a thunderstorm is approaching, then there is a possibility of a tornado.
4. Types of tornadoes
A tornado is a narrow column of air rotating at great speed, stretching all the way to the ground from the base of the thundercloud. A person will not always be able to recognize a tornado at first glance, since it consists of wind that cannot be seen. An essential feature is a funnel that consists of water droplets. Debris and dust that may be contained in the funnel can make a tornado noticeable. Researchers of this phenomenon have concluded that a tornado may not always touch the ground.
There are two types of this natural disaster:
– tornadoes that arose as a result of very strong thunderstorms;
– tornadoes, the occurrence of which was influenced by other factors.
The most dangerous are tornadoes that appear as a result of thunderstorms.
A superstorm is a thunderstorm that lasts more than 1 hour and is continued by an air current that is constantly rotating.
A tornado, which belongs to the second type, is nothing more than a whirlwind of dust and debris that forms near the surface of the earth, along the line of the wind flow without a funnel. Another variant of a tornado is a tornado (hurricane). It looks like a narrow rope-shaped funnel.
The formation of tornadoes is an amazing mystery. The formation of vortices in nature occurs literally at every step, for example, a funnel formed when water flows out of a bathtub. A small funnel in the bathroom and a huge tornado are phenomena of the same order, however, in a funnel the swirling mass is directed downwards, and in a tornado - upwards. When figuring out how air currents move inside a vortex, it would be appropriate to mention the little experience of the great Albert Einstein. The scientist was very interested in the process that occurs in tea when stirring it with a spoon. It turns out that tea leaves floating on the surface, during intense rotation of the water, in some incredible way always ended up in the center of rotation. Einstein explained it this way: the lower layers of liquid rotate at a lower speed, and the upper layers rotate at a higher speed. That is why all the tea leaves gather towards the center of the cup and rise slightly upward.
5. How tornadoes form
When studying the causes of tornadoes, scientists use theoretical developments, data obtained during observations, physical models, but tornadoes have continued to plague people for decades. Supercell tornado (tornadoes resulting from the formation of a cloud supercell). The swirling updraft is the cornerstone in the formation of a Supercell storm and, as a result, a tornado. There are many theories as to how this process begins. For example: an air column may begin to twist as a result of a “shear” of winds when the air masses are at various heights from ground level move at different speeds or in different directions. The shear that ultimately results in a tornado occurs, for example, when winds blowing close to the ground are slowed by friction from contact with the surface, while in layers of the atmosphere further away from the ground, winds blow at speeds many times faster than the lower currents. As a result, the “invisible” air pipe begins to rotate horizontally. We still have many questions. From observations, scientists have found that about 20 percent of all severe storms usually produce tornadoes. Why does one storm cause a tornado, while another equally powerful one ends without it? What other factors besides updrafts fuel tornadoes? What is the role of downward air currents and differences in temperature and humidity (both in the vertical and horizontal directions of tornado propagation). Moreover, not all tornadoes are of thunderstorm origin, what can be said about such phenomena? Non-thunderstorm tornadoes do not appear as a result of strong circulation air masses over the entire area of the storm. These tornadoes are formed as a result of the vertical rotation of a section of air masses occurring near the very surface of the earth, with a diameter of about 1-10 km, the cause of which was the “displacement” of the wind. When an updraft rises above the location of such a state of air masses, there is a high probability of tornado formation. In eastern Colorado, similar non-thunderstorm tornadoes are common because... cold air brought from the mountain peaks collides with the hot air currents of the plains. Since such tornadoes occur mainly in poorly populated areas, scientists cannot accurately determine their strength, but in general, these are not very powerful winds.
6. Conditions for the formation of tornadoes
The detailed reasons for the formation of tornadoes are not yet fully understood. After all, if all the reasons are known, then it will be possible to avoid both the tornado itself and possible consequences from his “revelry”.
Today, some conditions are known under which tornadoes occur. For nucleation, moist warm air must be present in the lower layers of the atmosphere, and the winds must blow in a southerly direction. And in the upper layers of the atmosphere there should be dry and cold air. Under such conditions, an air mass rises at the surface of the earth, from where the tornado gains its energy.
The life of a tornado can be divided into three phases: initiation, development and decay. When a tornado originates in a rain or cumulonimbus cloud, a funnel appears that grows in a spiral towards the surface of the earth or water. The energy of a future tornado is generated by thermal convection, when heated air rises. With each passing minute, as the air rises, the rotation speed of the future tornado increases. The speed of rotation attracts more warm air, and warm air increases the speed of rotation. And so on in a circle until the power reaches its apogee. Then the second stage starts - the stage full development. Here the already formed tornado reaches maximum values in speed and size and begins its movement. More powerful and destructive tornadoes are observed on land; in the sea they are short-lived and not so strong.
The third stage is attenuation. Here the speed of rotation of the funnel decreases, the color changes from dark to light, and the tornado itself breaks approximately in half, one part goes to the ground, the other rises into the “mother” cloud.
The life of any tornado takes several tens of minutes. Only some of the most powerful ones can exist for several hours. The average speed of an average tornado is 60 kilometers per hour, and very rarely reaches 200 kilometers per hour.
7. Why do tornadoes occur?
Today, natural disasters such as tornadoes, tornadoes and hurricanes cause great destruction, loss of life and hundreds of millions of dollars in property losses. Meteorological experts believe that the most destructive hurricanes that have become more frequent over last decades, are directly related to global warming climate. And since the temperature in the atmosphere continues to rise steadily and uncontrollably every year, we should expect even more “gifts” from nature.
A tornado (tornado, as it is called in America) is a rotating heated air stream. The rotation speed can reach 1000 meters per second. For its formation in the atmosphere, thin rain clouds and a powerful vertical air flow between the cloud and the earth's surface are necessary. The most powerful and destructive tornadoes can travel up to 500-1000 kilometers, bringing down at the point of extinction everything that they collected along the way. The most destructive tornado occurred in the United States in the spring of 1974. Then it totaled more than 100 whirlwinds, which took the lives of more than 30 people (4000 were injured). The loss amounted to more than 700 million dollars.
The European tornado is no less dangerous. Although more powerful tornadoes form on vast plains, Europe has seen considerable destruction from such an “unexpected guest.” In Russia, in the same 1974, a tornado even toppled a 240-ton construction crane into the river.
Both tornadoes and tornadoes are local atmospheric formations, and if possible, encounters with them can be avoided. But what really frightens with its power is a hurricane. Typically, hurricanes affect the population of those countries located from 5 to 35 degrees in the northern hemisphere. Here such natural phenomena are most frequent. All hurricanes arise over the ocean, or more precisely over the warmest part of it. For a hurricane to form, the water temperature must be at least 27 degrees Celsius. From space it resembles the same tornado, only much larger. And on the periphery of the hurricane, new vortex flows in the form of tornadoes may form, which will make such an air front even more powerful and fierce.
The most “fatal” hurricane in human history (of course, what remains in history) was Hurricane Katrina, which struck the southern states of the United States on August 27-29, 2005. As he approached the coast, experts gave him highest score according to the Saffir-Simpson scale. The wind speed during Hurricane Katrina was 220-280 kilometers per hour.
The city suffered more than others in those days New Orleans, which was 80 percent destroyed. Hurricane Katrina claimed nearly 2,000 lives and caused economic losses of $125 billion.
Many countries around the world will allocate funds to study and combat such natural phenomena. But if we can still predict the approach of a hurricane or tornado, then we are not able to fight today.
8. Rules for naming hurricanes, tornadoes and typhoons
Until the world's first system for naming hurricanes appeared, these natural phenomena received their names by chance, without any systematicity. Sometimes hurricanes were named after the name of the saint on whose day the disaster occurred. This is how, for example, Hurricane Santa Anna got its name, reaching the city of Puerto Rico in 1825, on St. Anna’s Day. Also, the name of a hurricane could be given by the name of the area that suffered most from its impact. Sometimes the name was determined by the very form of this phenomenon. Thus, Hurricane Pin of 1935 got its name. The shape of this hurricane's trajectory resembled a pushpin.
Australian meteorologist Clement Wragg distinguished himself with a very interesting method of naming hurricanes: he proposed naming typhoons after the names of politicians who refused to vote in favor of allocating loans for meteorological research.
9. What's inside a tornado?
To this day, a tornado is considered a poorly understood atmospheric phenomenon. The main difficulty of study is that tornadoes are very difficult to study experimentally. Such natural phenomena occur quite often, but the time of their occurrence is impossible to predict. Mobile laboratories “chasing a tornado” are destroyed before the center of this hurricane can reach them.
Create a full-fledged tornado in laboratory conditions up to now no one has succeeded, since this requires the presence experimental setup several hundred meters in size. All the information available to scientists today was obtained by an indirect method. Note that astronomy is used to study tornadoes. Since it is impossible to “get inside” the phenomenon itself, you just have to observe it, while trying to understand its nature.
What is at the very center of a tornado? It is known so far that there is an area of low pressure in the center. In more powerful tornadoes, the pressure difference between the inside and outside is 0.1 atmospheres or more.
Conclusion
Tornadoes, storms and hurricanes are some of the most powerful forces of nature. They cause significant damage to the population, cause significant difficulties, and lead to casualties. They are compared to floods and earthquakes in terms of their destructive impact. The destructive effect of tornadoes, storms and hurricanes depends on the high-speed pressure of air masses, which has a propelling effect and determines the force of the dynamic impact.
Hurricanes and storms are often accompanied by hail and thunderstorms. A hurricane originates in the ocean and comes to land, bringing with it catastrophic destruction. As a result joint action wind and water, lungs are demolished and strong buildings are damaged, fields are devastated, communication and power lines are broken, trees are uprooted and broken, people and animals die, roads are destroyed, ships sink.
Why is a hurricane so scary?
Firstly, with its hurricane waves that hit the coast. A hurricane seems to push huge waves onto the shore in front of it, the height of which reaches several meters. In coastal areas they cause severe flooding and destroy everything that gets in their way. Eyewitnesses of such powerful and terrible waves rarely survive.
Secondly, catastrophic floods and downpours. The thing is that when a hurricane is born, it absorbs huge masses of water vapor, which condenses and gathers into powerful and large thunderclouds that cause floods not only in coastal zone, but also in areas significantly removed from the coast, and serving as a source of catastrophic downpours. The rainfall that accompanies hurricanes also causes landslides and mudflows.
List of used literature
1. J. Christenson “Tornadoes and tornadoes” M. Ecolitgiz 2004
2. Sibiryakov A.S. "World natural disasters» L. Publishing house "Delo" 2009
3. Khanzhin G.B. “Winds from within” Infra-M, 2001.
