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What is the name of a storm in the tropics. Tropical cyclones. What is CLIPER

Archived article from #6(42) 2005

Tropical cyclones- one of the most amazing and, at the same time, formidable and destructive natural phenomena on Earth, rampaging over the tropical waters of all oceans, with the exception of the southern Atlantic and the southeast Pacific.

On our planet, on average, about 80 tropical cyclones are observed per year.

Intense tropical cyclones in each region have their own name. In the Atlantic and the Pacific Northeast they are called hurricanes; in the Pacific Northwest - by typhoons; in the Arabian Sea and the Bay of Bengal - cyclones; in the southern part indian ocean- orkans; off the coast of Australia - willy-willy; in Oceania - willy-wow; in the Philippines - baguio.

Tropical cyclones are huge whirlwinds reaching 1000-1500 km in diameter and extending through the entire thickness of the troposphere. A distinctive feature of tropical cyclones is a significant drop in pressure over short distances, which leads to the formation of hurricane-force winds. The pressure in the center of developed cyclones is about 950-960 hPa (the minimum of the recorded ones is 855 hPa).

Tropical cyclones occur over warm ocean waters in the tropics of both hemispheres in the latitude zone 5-20°. They are a formidable product of the interaction of the ocean and the atmosphere.

Most tropical cyclones are formed in the intratropical convergence zone - the zone of convergence of the trade winds of the two hemispheres, or trade winds, and equatorial westerly winds. Such a convergence zone is characterized by the presence of disturbances of varying intensity - some of them reach the stage of tropical depressions, some of which, under favorable conditions, develop into a tropical storm and hurricane. What contributes to the origin and further intensification of a tropical cyclone? First of all, this is the presence of an initial disturbance and a slight horizontal wind shear between the lower and upper troposphere. To create the “twisting” effect, a sufficient value of the Coriolis force, due to the rotation of the Earth around its axis, is necessary - tropical cyclones do not form near the equator, where the horizontal component of this force is zero. One of the conditions for the formation of tropical cyclones is the presence of humid unstable air and the development of convection.

Finally, this is the existence of an energy source - the thermal potential of the ocean. Simply put, tropical cyclones form over the ocean when its surface temperature exceeds 26°C. The ocean supplies a significant portion of the heat needed to maintain low pressure at the center of the cyclone. With an increase in water temperature, evaporation increases and the flow of the so-called latent heat increases, which forms a warm core in the middle troposphere, which causes a sharp decrease in pressure in the center of a tropical cyclone. A tropical cyclone can be thought of as a heat engine, whose work is connected with the ocean as a source of energy and as a trigger mechanism - the initial vortex is formed over the overheated region of the ocean. In addition, the thermal state of the ocean also affects the trajectory of tropical cyclones. But at the same time, the evolution of tropical cyclones is also determined by various atmospheric processes. We are dealing with a complex complex of ocean-atmosphere interactions.

A mature tropical cyclone is the most powerful atmospheric vortex, which is characterized by large pressure gradients (differences) and, consequently, hurricane-force winds - up to 90 m/s, with the belt of maximum winds located between 20 and 50 km from the center. In tropical cyclones, powerful cloudiness develops, the amount of precipitation can reach 2500 mm per day. In well-developed cyclones, a phenomenal phenomenon is observed - the eye of the storm - an area where the sky clears up, the wind weakens, sometimes to calm, and precipitation suddenly stops at its border. The eye is surrounded by a wall of powerful clouds. Satellite images have revealed the existence of "hot towers" - high-altitude zones of rain clouds, which are located above the "walls" of this very "eye" much higher than the main part of the hurricane. "Towers" extend to the very "ceiling" - the upper layers of the troposphere. According to experts, "hot towers" play a key role in the process of amplifying the power of a hurricane. By the way, such “towers” ​​were also discovered in Hurricane Katrina. The appearance of the eye of the storm is associated with an increase in centrifugal force as it approaches the center of the cyclone. The average diameter of the "eye" is 20-25 km, in destructive hurricanes and typhoons it is 60-70 km. There are also two-eyed tropical cyclones.

The energy of a tropical cyclone is very high; according to experts, an average tropical cyclone generates an amount of energy equal to several thousand atomic bombs.

In three weeks, a hurricane generates energy comparable to what our Bratsk hydroelectric power station would have generated in 26,000 years. Humanity is not yet able to use this energy, nor to receive it in such quantity from any other sources.

The resulting tropical cyclone first moves from east to west, gradually deviating to higher latitudes: in the northern hemisphere - to the northwest. But if the cyclone reaches 20-30° latitude above the ocean, it begins to go around the subtropical anticyclone and its direction changes to the northeast. Such a point of the trajectory is called a turning point. Trajectories of movement of cyclones are mostly curvilinear, sometimes even "loops" appear. The average speed of tropical cyclones within the tropics is only 10-20 km/h. Coming out on land or in middle latitudes, a tropical cyclone fades or turns into an intense cyclone of temperate latitudes. The Russian Primorye in the summer-autumn period is often exposed to such cyclones - former typhoons that bring abnormal precipitation and hurricane wind. So, in 1973, a typhoon that hit Primorye brought more than half of the annual precipitation to Vladivostok. The author of the article experienced all the "charms" of the raging elements, when in August 1979 the typhoon "Irving" hit the Far East, flooding the Primorsky and Khabarovsk Territories.

In hydrometeorological practice, depending on wind speed, tropical disturbances are divided into tropical depression, tropical storm, severe tropical storm, tropical cyclone, typhoon, hurricane. In turn, the latter are divided into five categories (the Saffir-Simson hurricane scale) depending on the wind speed. The fifth category includes hurricanes with speeds exceeding 70 m/s.

Tropical cyclones that become tropical hurricanes get their names. This tradition dates back to World War II, when meteorologists from the Air Force and naval forces The United States monitored typhoons and, to avoid confusion, named typhoons after their wives or girlfriends. After the war, the US National Weather Service compiled an alphabetical list of female names to facilitate communication and avoid embarrassment in the development of several cyclones in the region. When, in 1979, the real essence of the strong half of humanity was finally understood, the World Meteorological Organization (WMO), together with the US National Weather Service, included in the list and male names. Justice has prevailed. (Not all evil is from a woman!) These lists are constantly used and pre-compiled for each year and each region. However, in the event that a tropical cyclone is particularly destructive, the name given to it is struck off the list and replaced by another. So we can say quite definitely - we will never hear about a hurricane named "Katrina" again.

The destructive effect of tropical cyclones is due to hurricane-force winds, the deadly streams of water that hit the coast with the arrival of a hurricane - up to 20 million tons of water per day. For example, in January 1966, tropical cyclone Denis swept over Reunion Island in the Indian Ocean, bringing an incredible amount of precipitation - 182 centimeters per day. Added to the rainfall is "storm surge" - a rise in sea level that reaches 10 m in extreme cases. Storm surge floods are the most devastating effects of hurricanes. In 1970, Cyclone Ada in the Indian Ocean flooded the low-lying coast of Bangladesh with surge waves. More than 300 thousand people died then. Hurricane Hugo in 1989 brought down a wall of water 6 meters high on South Carolina. Such a blow can destroy buildings, roads, wash out the coast.

In the northern hemisphere, the "hurricane" season lasts, on average, from May to November. The longest period of development of tropical cyclogenesis is observed in the western Pacific Ocean. According to the Russian Hydrometeorological Center, which has collected a database of tropical cyclones around the globe, an average of 26 tropical cyclones form in the western Pacific Ocean. In the Atlantic, the peak of hurricanes falls on August-September and there are about 9-10 cyclones per year. Research scientists have shown that in recent decades tropical cyclone activity increased in the Atlantic. So, from 1970 to 1979 their number was 81, from 1980 to 1989 - 96, from 1990 to 1999 - 105; moreover, 19 tropical cyclones were recorded in 1995 (the record still remains for 1933, when 21 cyclones formed in the Atlantic). According to the forecasts of American scientists, this trend will continue in the first decades of the 21st century, and this year 2005 may already break all records. This is primarily due to rising ocean surface temperatures. As satellite data showed, in 2005 the water surface temperature in the Atlantic basin increased by 2-4°C on average compared to previous years.

Until recently, the record holder among the Atlantic cyclones was Hurricane Andrew, which swept over the states of Florida and Louisiana in late August 1992 and caused $ 25 billion in damage. The minimum pressure in its center dropped to 923 hPa, and the wind speed reached 76 m/s.

However, Katrina, apparently, turned out to be a record holder in its parameters: the minimum pressure in its center was 902 hPa, while the wind speed at the same time exceeded 75 m/s (gusts up to 90 m/s). Katrina originated on August 23, 2005 east of the Bahamas and, passing through southern Florida and intensifying in the Gulf of Mexico, where the water temperature exceeded 31 ° C, hit New Orleans on August 29, 2005, destroying dams and completely flooding the city. The death toll exceeded a thousand people, and the economic damage amounted to tens of billions of dollars. It was the most destructive hurricane ever to hit the coast. North America.

Following Katrina, Rita rushed to the coast of the United States, becoming the seventeenth tropical storm of the 2005 hurricane season.

Fortunately, she weakened before causing colossal harm. Both Katrina and Rita originated north of normal latitudes, where Atlantic tropical cyclones swirl. But the most unusual for the Atlantic was the twentieth hurricane named Vince. He managed to spin in the area of ​​the Azores, which is much north (30-35 parallel) of the usual area of ​​​​their formation. True to reach great intensity it failed and, reaching Category One, Vince quickly weakened to a tropical storm.

Tropical cyclones significantly redistribute energy in the atmosphere and therefore, despite their "compact" size, influence atmospheric processes far beyond their "habitats". For example, climatologists have noted interesting fact relationship between the frequency of hurricanes in the Atlantic and fair weather in Europe. As a rule, with an increase in the activity of tropical cyclogenesis, large sedentary cyclones form over Scandinavia. Along their periphery most Western Europe, southerly winds spread, which provide a stable warm weather. At the same time, Eastern Europe is in the grip of an anticyclone, which determines good weather. So our protracted "Indian summer" of 2005 is partly connected with the "raging" Atlantic.

There is no need to talk about the importance of studying tropical cyclones and predicting their evolution. Direct measurements in a cyclone are practically impossible, although many useful information was obtained during aircraft sounding and special expeditionary observations. Modern methods of research and forecast of tropical cyclones are based on numerical modeling and the use of satellite information, laboratory experiments. Methods have been developed for predicting the occurrence, evolution, and direction of movement of these cyclones based on numerical methods and satellite data. Although it is still impossible to accurately calculate the place of origin of a tropical cyclone, it is quite realistic to determine the most probable area of ​​its origin. Over the past 30 years, significant progress has been made in predicting the trajectories of cyclones.

The enormous damage caused by tropical cyclones poses the problem not only of predicting their development and movement, but also of possible influence on them in order to reduce their intensity and change the trajectory of movement. A wide variety of projects were proposed: scattering clouds with dry ice or silver iodide, cooling the ocean with icebergs, covering the water with a special oil film, irradiating the epicenter of a hurricane with microwaves from space or undermining it with hydrogen bombs. It should be noted that all of them are quite expensive and may turn out to be absolutely meaningless if there is no accurate forecast of the place of origin, size and intensity of the cyclone. In addition, it is impossible to calculate the consequences of such impacts, which can be no less devastating than the tropical cyclone itself. So for now, we can only hope to improve the methods of forecasting tropical cyclones and adequately respond to the warnings of specialists. And even now, thanks to the improvement of warning systems and methods of saving people, the number of human victims has begun to gradually decrease.

Text: Olga Razorenova (Senior Researcher, Institute of Oceanology RAS)
Photo: Levan Mtchedlishvili

Tropical cyclones, hurricanes, typhoons

especially dangerous phenomenon nature are deep cyclones of various origins, which are associated with strong winds, heavy precipitation, surges and high wind waves in the sea. The depth of a cyclone is determined by the air pressure at its center.


The size and power of deep cyclones depends on many factors and, first of all, on the place of their origin. The cyclones that originated in the tropical latitudes are distinguished by the greatest power. They are called tropical in contrast to extratropical cyclones, among which are cyclones of temperate latitudes and arctic cyclones. The higher geographical latitude the nucleation of a cyclone, the lower its ultimate power.


Tropical cyclones carry colossal reserves of energy and have great destructive power. The kinetic energy of a medium-sized tropical cyclone is comparable to the explosion energy of several powerful hydrogen bombs and is about 10% of the total kinetic energy of the northern hemisphere.


Most often (in 87% of cases) tropical cyclones occur between latitudes 5° and 20°. In more high latitudes Ah they occur only in 13% of cases. Tropical cyclones have never been recorded north of 35°N. sh. and south of 22° S. sh.


Tropical cyclones can occur at any time of the year in the tropical parts of all oceans except the southeast Pacific and the south Atlantic. Most often they form in the northern part tropical zone Pacific Ocean: here, on average, about 30 cyclones are traced per year. The main season for the development of tropical cyclones is August-September; in winter and spring, their frequency is very insignificant.


Tropical cyclones usually originate over the oceans, and then move over their water areas and come to the coast of continents, islands, bringing down on them the strongest winds, rain showers, causing a surge wave up to 8 m high, as well as waves in the open sea, over 10 m high.


Tropical cyclones that have reached significant intensity in each region have their own name. In the eastern part of the Pacific Ocean and in the Atlantic they are called hurricanes (from the Spanish word "uracan" or the English "hurricane"), in the countries of the Hindustan Peninsula - cyclones or storms, in Far East- typhoons (from the Chinese word "tai", which means strong wind). There are also less common local names: "willy-willy" - in Australia, "willy-wow" - in Oceania and "baguio" - in the Philippines.


To describe the intensity of tropical cyclones, the Saffir-Simpson scale is used (Table 1). 3.3.1.1. It shows that as the cyclone deepens, the wind speed and surge wave height increase in it, and the cyclone itself is classified either as a storm or as a hurricane from the first to the fifth category.


This scale is used by almost all hurricane and typhoon watch centers. Recently, the Saffir-Simpson scale has also been used to classify deep extratropical cyclones that have reached storm or hurricane strength. From this table it follows that hurricanes and typhoons have five categories (from a hurricane or typhoon of the first category H1 to a hurricane or typhoon of the fifth category H5). Tropical depressions and tropical storms are not categorized.

Table 3.3.1.1. Tropical cyclone scale

Type Category Pressure, mb Wind, km/h Surge height, m tropical depression TD <63 tropical storm TS 63-117 Hurricane H1 >980 119-152 1,3-1,7 Hurricane H2 965-980 154-176 2,0-2,6 Hurricane NZ 945-965 178-209 3,0-4,0 Hurricane H4 920-945 211-250 4,3-6,0 Hurricane H5 <920 >250 >6

IN life cycle A tropical cyclone can be divided into four stages:


1. Stage of formation. It begins with the appearance of the first closed isobar. The pressure in the center of the cyclone drops to 990 mb. Only about 10% of tropical depressions develop further.


2. The stage of a young cyclone, or the stage of development. The cyclone begins to deepen rapidly; there is a significant drop in pressure. Hurricane-force winds form a ring around the center with a radius of 40-50 km.


3. Stage of maturity. The pressure drop in the center of the cyclone and the increase in wind speed gradually stop. The area of ​​storm winds and intense showers is increasing in size. The diameter of tropical cyclones in the developmental stage and in the mature stage can vary from 60-70 to 1000 km.


4. Stage of attenuation. The beginning of the filling of the cyclone (growth of pressure in its center). Attenuation occurs when a tropical cyclone moves into an area of ​​more low temperatures surface of the water or when moving to land. This is due to a decrease in the influx of energy (heat and moisture) from the surface of the ocean, and when it comes to land, it is also due to an increase in friction against the underlying surface.


After leaving the tropics, a tropical cyclone may lose its specific properties and turn into an ordinary cyclone of extratropical latitudes. It also happens that tropical cyclones, remaining in the tropics, go to the mainland. Here they quickly fill up, but at the same time they manage to produce a lot of destruction.


Since ancient times, there has been a practice of assigning proper names to destructive hurricanes and typhoons. Naming principles have changed over time. For hundreds of years, Caribbean hurricanes have been named after saints. church calendar, on the day of which a devastating hurricane fell on a large settlement.


Under these names, hurricanes entered the annals and legends. An example is the hurricane Santa Anna, which hit Puerto Rico on July 26, 1825 with exceptional force. IN late XIX in. Australian meteorologist Clement Wragg began referring to tropical storms by female names. Since 1953 national center hurricanes, the United States began to publish preliminary lists, according to which Atlantic tropical storms were named.


Until 1979, only female names. Since 1979, both female and male names have been used. The practice of compiling preliminary lists of hurricanes and typhoons has spread to all regions. Now there are 11 such regions in the World Ocean. These preliminary lists for all regions are created and updated by a special international committee World Meteorological Organization (WMO).


The damaging factors of hurricanes and typhoons:


Kinetic wind energy;

Intense precipitation;

Surge wave;

Storm waves of considerable height.


Associated nuclear events: strong wind, heavy seas, heavy rains, heavy hail, high waters, floods, collapses, landslides, erosion and processing of coasts.


Hurricanes cause enormous damage to the coasts of the North and South America, islands in the way of their distribution. They hit these coasts with a frequency of once every few years, sometimes forming series within one year. One of the most destructive hurricanes - Mitch in October 1998 claimed the lives of 10,000 people in Honduras and Nicaragua and left 2 million people homeless.


The hurricane caused the most severe flooding in these countries in the last two hundred years. The total economic damage caused by the hurricane exceeded $5 billion. The world's greatest economic damage was caused by Hurricane Andrew, which swept over the United States from August 23 to 27, 1992. Insurers paid out $17 billion, which covered about 57% of the losses from the hurricane.


The underdeveloped countries of the Caribbean suffer the heaviest damage from hurricanes, the consequences of which they recover for years. Hurricanes in the middle latitudes are rare: once every 8-10 years. In January 1923, a hurricane captured the entire European part of the USSR, the center of the hurricane passed through Vologda. In September 1942, a hurricane swept over the central regions of the European part of our country.


The pressure difference was very great, and therefore in some places hurricane-speed winds were formed. The usual speed of cyclones is 30-40 km/h; but there are speeds of more than 80 km / h. The September 1942 cyclone traveled 2,400 km in one day (i.e., its speed was 100 km/h). On November 18, 2004, the hurricane hit Germany, then moved to Poland and Kaliningrad.


In Germany, the wind speed reached 160 km/h, in Poland - 130 km/h, in Kaliningrad - 120 km/h. 11 people died in these countries, 7 of them in Poland. Everywhere the hurricane caused floods, power lines cut, damage to roofs of houses, and uprooted trees.


Annual losses from typhoons cause significant damage to the economies of several Asian countries. Most economically underdeveloped countries have great difficulty repairing the damage caused by typhoons. Of the 25-30 typhoons that appear every year over the western part of the Pacific Ocean, the Sea of ​​Japan and Primorsky Krai, i.e. on the territory of Russia, come out in different years from one to four typhoons, bringing sharp deterioration weather and causing significant economic damage.


All of them arise over the ocean to the northeast of the Philippines. The average duration of a typhoon is 11 days, and the maximum is 18 days. The minimum pressure observed in such tropical cyclones varies widely: from 885 to 980 hPa, but when typhoons enter our territory, the pressure in their centers rises to 960-1005 hPa.


The maximum daily precipitation reaches 400 mm, and the wind speed is 20-35 m/s. In 2000, four typhoons hit the territory of Primorye, one of which - BOLAVEN - turned out to be the most destructive: 116 settlements, 196 bridges and about 2,000 km of roads were damaged. A total of 32,000 people were affected and one person died. Economic damage amounted to more than 800 million rubles.


Forecasting hurricanes and typhoons, detecting their origin, tracking their trajectories is the most important task of the meteorological services of many countries, primarily the USA, Japan, China, and Russia. To solve these problems, space monitoring methods, modeling of atmospheric processes, synoptic forecasts are used.


To reduce damage from hurricanes and typhoons, primarily in terms of human casualties, methods of warning, evacuation, adaptation of industrial processes, engineering protection of coasts, buildings, and structures are used.

The destructive activity of typhoons and hurricanes is carried out as a result of the combined action of the colossal force of the wind, the huge amount of precipitation, the stormy rise in the ocean level and the giant waves that form.

The Beaufort scale for a unified assessment of the state of the sea from one (calm sea) to 12 points (hurricane - the sea is white from foam and waves reaching a height of 15 m) turned out to be unsuitable for characterizing wind speed during typhoons and hurricanes. To these 12 points, 5 more were added; the last 17 points corresponds to a wind speed of 460 km/h.

Modern instruments are not capable of registering wind speeds of more than 300 km/h. A record speed is considered to be approximately 400 km / h, which means not an instantaneous gust, but a wind blowing for 5 minutes. Separate gusts have a speed of 20 - 30% more.

In tropical cyclones, wind speeds often reach 300-400 km/h. Such speeds are not measurable. They are judged by the destruction that cyclones leave behind. These hurricanes often drop heavy rain and hail. Waterfalls falling from the sky and accompanied by the roar of the wind are terrifying. There are cases when, in areas of future typhoons, the surfaces of bays were covered with dead fish that died from excess fresh water.

Tropical cyclones on the way of movement cause huge material damage and take away a lot of human lives.

The inhabitants of the Philippine Islands, Indochina and Japan have known the word "typhoon" since time immemorial. Typhoons in the Bay of Bengal have many victims. They contribute to the occurrence of storm floods that inundate low-lying, densely populated coasts.

There are cases when one typhoon claimed thousands of human lives, for example, typhoon Vera in September 1959 killed 5,500 people. This number will increase significantly if we take into account people who died later from starvation and disease.

The damage inflicted material values, can be conditionally divided into direct and indirect. Direct is the damage that manifests itself directly during the action of the storm (destruction of buildings, fires, loss of crops, etc.). Indirect damage is damage that manifests itself for a long time after the passage of typhoons and hurricanes over islands and continents. For example, the absence of a crop for several years in those fields from which the surface layer of soil was carried away, a reduction in production in destroyed factories and factories. The amount of indirect damage caused by a tropical cyclone can be several times greater than the amount of direct damage. Long-term statistics of observation of tropical cyclones made it possible to identify some patterns that relate the amount of damage caused to the physical characteristics of tropical cyclones. This allows you to get a rough idea of ​​the scale of the impending disaster.

The biological significance of cyclones lies in their ability to carry seeds of plants, and sometimes rather large animals, over great distances. Apparently, it was these winds that contributed to the settlement of many volcanic and coral islands that arose in the expanses of the oceans, and the migration of plants and animals. The hurricane of 1865 brought pelicans to Guadeloupe, previously unknown there.

The famous Great Hurricane in October 1780 destroyed the city of Savannah-la-Mar (Georgia, USA). According to an eyewitness, the inhabitants were petrified with amazement when they saw the approach of an unprecedented wave; sweeping away all obstacles with one gigantic squall, it flooded the city and demolished everything and everything. Seven days later the storm reached maximum strength. She completely devastated the island of St. Lucia, where 6,000 people died under the ruins, and sank the English fleet anchored off the island. The sea here rose so high that it flooded the fleet and, bringing the ship on the crest of one of its giant waves, threw it onto the naval hospital, destroying the building with the weight of the ship. The hurricane then headed for the island of Martinique, where 40 French transport ships carrying 4,000 soldiers were sunk. The islands of Dominica, St. Eustatius, St. Vincent, Puerto Rico, located to the north, were also devastated and sunk big number ships caught in the path of a cyclone.

On the night of November 13, 1970, an incredible typhoon hit the coastal regions of East Pakistan (since 1971, the People's Republic of Bangladesh). A powerful wave up to 8 m high, raised by the wind, passed over a chain of densely populated islands. It was colossal water wall, boiling and seething, a huge shaft of water that the ocean threw out. Sweeping away everything in its path, it hit the coast and, together with a hurricane wind, brought catastrophic destruction. For several hours, these islands and part of the mainland coast were under water. The consequences of the typhoon are catastrophic: bridges were torn down, highways and railways were destroyed, entire villages were completely destroyed along with the inhabitants. More than 10 million people were affected by the typhoon, according to newspaper reports. The death toll exceeded half a million, and according to some sources, about a million people. One of the most powerful natural disasters in the history of mankind has happened.

In 1974, a hurricane of extraordinary strength hit 11 states of North America. Sowing death and destruction, the hurricane and its accompanying tornadoes in 8 hours left on their way, according to published data, 350 killed, thousands of wounded and missing. In the states of Illinois, Indiana, Ohio, Kentucky, West Virginia, Virginia, Tennessee, North Carolina, Alabama and Georgia, hundreds of houses and shops, schools, hospitals and churches were destroyed. Property damage, according to incomplete data, is estimated at $ 1 billion. Among the most severely affected by the hurricane is the city of Zinia in Ohio. According to eyewitnesses, the hurricane hit suddenly around 5 o'clock. evening, rumbled like a passenger train rushing at great speed. In a city of 25,000, more than 70% of buildings were completely or partially destroyed, including the state university. The city of Brandenberg ceased to exist. In Alabama, the cities of Jasper and Guin are razed to the ground.

On the eve of 1975, tropical cyclone "Tracy" almost completely destroyed the capital of the northern territory of Australia, Darwin - a city with a population of 44 thousand people. The wind force reached a speed of 260 km / h. The hurricane tore roofs off houses like balls, tossed tourist buses through the streets. Numerous cottages fell apart under the pressure of the wind, like houses of cards. But administrative buildings and high-rise hotels turned out to be hardly more stable. Turned into mountains of rubble and debris business center Darwin. A large naval base located near the city was destroyed. Several ships sank.

In 1980, during August and September 1980 alone, there were four tropical cyclone events in the northern hemisphere and one event in the southern hemisphere, of which two were hurricanes in the Caribbean and three were typhoons in the Pacific.

Hurricane Alley was recorded in early August off the coast of Haiti and Jamaica. The wind speed in it reached 70 m/s. The second hurricane, Ermina, was observed in the 20th of September off the northern coast of Honduras, as well as off the coast of Mexico and Guatemala. The wind speed in it reached 30 m/s.

Typhoon Orchid originated in the Western Pacific Ocean and swept over the Japanese Islands and South Korea on September 11-12, causing extensive damage and flooding there. The influence of this typhoon became noticeable days later in the Khabarovsk and Primorsky Territories and on Sakhalin. Heavy rains and wind were observed, the wind speed in some places reached hurricane (33 m/s). About a month later, in mid-October, another typhoon came to the Japanese islands of Kyushu and Shikoku from the south, temporarily disrupting not only air, but also railway communication.

At the beginning of the third decade of September, Typhoon Kei appeared in the southeastern Pacific Ocean, in the center of which the wind speed reached 30-40 m/s.

There were tropical cyclones in subsequent years, both in the northern and southern hemispheres. In particular, tropical cyclones Eilena, which hit the Comoros in the Indian Ocean on January 10, 1983, and Andri, which caused great destruction on the northwestern coast of the island of Madagascar in the Indian Ocean, turned out to be very destructive.

The year 1985 was also a fruitful year for tropical cyclones: seven tropical cyclones - typhoons passed in the South China Sea during the summer and autumn of this year, causing catastrophic floods and human casualties in the coastal regions of Vietnam and China.

One of the typhoons, Lee, penetrated far north to the Korean Peninsula and, turning into an ordinary cyclone, brought with it heavy rains to the territory of the Soviet Primorye in mid-August.

Another typhoon on September 10-12 destroyed a third of the fruit crop and caused damage to about 90% of the cultivated area on the Japanese island of Honshu.

In late October, Typhoon Saling claimed the lives of more than 60 residents of the island of Luzon in the Philippines and caused more than 700 million pesos of damage to the island's farms. Almost simultaneously in the other hemisphere, in the Gulf of Mexico, another tropical cyclone arose - Hurricane Juan, which severely affected the inhabitants of several coastal states of the United States, and a month later - Hurricane Keith, which caused flooding and significant destruction in northern Cuba and the United States. Hurricane Keith in terms of intensity and extent of damage caused by about. Cuba and the coast of the Florida peninsula proved to be one of the most ferocious in the last 50 years; gusts of wind and ocean waves running ashore destroyed many thousands of houses, more than a million people had to be evacuated from disaster zones, and there were human casualties.

Tropical Cyclone Jeanne (September 2004) -- Caribbean Sea, Haiti. The death toll from heavy rains, floods and landslides on the island of Haiti caused by Hurricane Jeanne could reach 2,000, according to the Associated Press. As of September 23, almost 1,100 victims are already known, and another 1,250 people are missing. Most a large number of victims - in the city of Gonaives in the northern part of the island. According to authorities, 1,013 people died here. Representatives of the Red Cross fear the spread of epidemics through the water, in which the bodies of drowned people were located for several days. The water level in some places exceeds four meters, and as it declines, more and more victims are found. The President of Haiti called what is happening a humanitarian catastrophe and asked international community about help. In May 2004, the island had already suffered one of its most terrible floods over the entire history, as a result of which about 2.5 thousand people died.

Hurricane Katrina is one of the most destructive hurricanes in US history. As a result of the disaster, 1,836 residents were killed and the economic damage amounted to $81.2 billion. Physical characteristics. Before it reached the coast of the United States, it was assigned a level 5 hurricane scale on the Saffir-Simpson Hurricane Scale. Fortunately, about 12 hours before landfall, the hurricane weakened to a Category 4 level. The wind speed during the hurricane reached up to 280 km / h (according to other reports 62 m / s (? 223 km / h). August 27, 2005 passed over the coast of Florida near Miami and turned towards the Gulf of Mexico. August 29, 2005 reached south- east coast of the United States in the Louisiana and Mississippi region. Due to the location below sea level, many cities of the southeast coast of the United States were flooded. In New Orleans, this happened with 80% of the city, many buildings collapsed. Economic damage amounted to $ 125 billion. ( estimate, 2007).About 800,000 people were left without electricity and telephone service.The officially confirmed number of victims was 1407 people, according to later data 1600, of which more than 720 were in New Orleans; in addition, as of December 2005, 47 people were missing More than a quarter of the population of New Orleans (150 thousand people) still have not returned to the city (August 2006).

March 14, 2007 Madagascar again experienced the blow of the elements. Another tropical cyclone, Indlala, reached the northeast coast of the island, reaching category 3 in strength. The wind speed in this cyclone reached 115 knots with gusts up to 140 knots. Reportedly news agencies, over the past days, this cyclone claimed the lives of 36 people, 53 thousand 750 people were left homeless. Since December 2006, Indlala has become the fourth cyclone to hit Madagascar. On March 19, 2007, he left the island. While in the north of the island, due to powerful cyclones, devastating floods are noted, its southern part is experiencing drought and famine. The cyclone season in the South Indian Ocean usually lasts from November to March. But the 2006/07 season differs from the previous ones in greater activity.

On October 7, 2008, Mexico was literally in the grip of tropical cyclones. Tropical Storm Marco has formed in the Gulf of Mexico. Wind gusts reached 27 m/s. Storm "Marco" came close to the coast. Brought torrential rains. On the other side of Mexico, over the water area Pacific Ocean, another cyclone is Hurricane Norbert.

Lecture plan

    The concept of a tropical cyclone.

    Origin and structure of tropical cyclones.

    Areas of origin and main paths of tropical cyclones.

    Development stages and trajectories of tropical cyclones.

    Weather in tropical cyclones.

    Signs of an approaching tropical cyclone.

    Determination of the ship's position relative to the center of a tropical cyclone.

Basic theoretical provisions

    The concept of a tropical cyclone.

Cyclonic activity is observed not only in temperate and high latitudes. Near the tropical fronts of both hemispheres (in the latitudinal zone from 5 to 25° N and S), menacing natural phenomena, mesoscale vortices, or tropical cyclones arise on the Earth. Usually, a large number of cyclonic disturbances occur at low latitudes, but they are weakly expressed: the pressure in the center is only 1–2 mbar below the surrounding baric field, the winds are weak, and move slowly from east to west. But from time to time these disturbances begin to develop and turn into deep tropical cyclones with large baric gradients and storm winds. They are related to frontal cyclones of temperate and high latitudes by storm and hurricane winds, similar rotational circulation of eddies, abundant precipitation falling from their cloud systems, and proportionality.

The fundamental differences between frontal and tropical cyclones are in their energy, vertical structure of air flows, wind speed, direction of movement and lifetime of the eddies themselves.

Tropical cyclones are relatively small but very deep eddies with high kinetic energy. For the development of a tropical cyclone, a large energy of air mass instability is required. A powerful rise of very warm and humid air above the perturbation that has arisen is a necessary condition for its development.

The pressure at the center of a tropical cyclone is usually 980–950 mbar, in some cases below 930 mbar. A tropical cyclone is 100–300 miles in diameter, but sometimes more.

2. Origin and structure of tropical cyclones.

Due to the colossal energies (in some cases, the wind speed in hurricanes exceeds 120-150 m/s), the amount of precipitation falling per day reaches a height of 20 m or more.

In the central part of the hurricane, under the action of centrifugal ejection of air, with a small inflow of air in the surface layer, the pressure drops rapidly. Initially, a weak baric depression intensifies, and after a few days a powerful cyclone begins to move to the west, increasing its depth and speed of movement more and more, and the strength of the wind in it also increases. The cyclone develops into a tropical hurricane.

According to frontal theory, the occurrence of a hurricane is explained by the interaction of air masses of the northern and southern hemispheres on the tropical front in the zone where the trade winds meet. Here, due to the intensive heating of the ocean surface, there is a significant contrast in the temperatures of the lower and upper layers of the atmosphere, which creates a great instability of air masses - powerful convective movements.

wave theory The origin of hurricanes is trying to connect the passage of long (up to 2000 km) eastern waves of atmospheric pressure. These waves, moving from east to west, lose their stability and turn into eddies - tropical cyclones.

There are four stages in the development of any tropical cyclone to an intense hurricane:

- stage of formation- unstable weather, squally winds of various directions. The center of the cyclone is outlined. The wind strength near it (50-100 nautical miles) does not exceed 7 points;

- young cyclone– further pressure drop, formation of a belt of hurricane winds around the center of the cyclone. Formation in the center of the cyclone of clear weather with light winds or calm - "eyes of the storm";

- mature hurricane– cessation of pressure drop and wind increase. The area occupied by the hurricane increases to a maximum, the symmetry of the hurricane is broken. Bad weather in its right half it is observed on a larger area than in the left.

- hurricane destruction. This stage occurs, as a rule, after the hurricane turns through the polar course to the east. The intensity of the hurricane weakens, the "eye of the storm" disappears and the hurricane takes on the features of an ordinary non-tropical (frontal) cyclone. Similar tropical hurricanes they also fade when moving to land, when the influx of moisture stops and air friction against the underlying surface increases.

All cyclones originating in the tropics are divided into four groups.

1st group. Tropical disturbance - has a weak tropical circulation.;

2nd group. Tropical depression - a weak tropical cyclone with a pronounced surface circulation, the highest steady wind speed in which does not exceed 12-13 m/s;

3rd group. A tropical storm is a cyclone, in which the highest steady wind speed reaches 33 m/s;

4th group. A tropical hurricane is a cyclone in which wind speeds exceed 33 m/s (60 kt).

Thus, tropical cyclones are classified as follows (Table 1)

The classification is based on the criterion of wind speed in the central region of a tropical cyclone. However, tropical cyclones differ not only in the wind regime, but also in the nature of the distribution of clouds, precipitation, and other meteorological elements (Table 1).

Table 1. Classification of tropical cyclones depending on wind speed.

In the homeland of hurricanes, in the tropics, air masses are very hot and saturated with water vapor - the temperature of the ocean surface at these latitudes reaches twenty-seven to twenty-eight degrees Celsius. As a result, powerful ascending currents of air arise and the release of the stored air solar heat and condensation of the vapors it contains. The process develops and grows, it turns out a kind of giant pump - into the funnel formed at the place of origin of this pump, neighboring masses of the same warm and vapor-saturated air are sucked in, and thus the process spreads further and in breadth, capturing more and more new areas on the surface of the ocean.

When you pour water from the bathtub through the drain hole, a whirlpool is formed. Approximately the same thing happens with the air rising up at the place where the cyclone originates - it begins to rotate.

The giant air pump continues to work, more moisture condensing on its funnel-shaped top, more heat being released. (American meteorologists have calculated that over a million tons of water can be lifted up in one day - in the form of steam, which continuously saturates the surface layer of the atmosphere; the energy released during condensation in just ten days would be enough for such a highly industrialized state, like the USA, for six years!). It is believed that a moderate cyclone releases approximately the same amount of energy as 500,000 atomic bombs with the power dropped over Hiroshima. Atmosphere pressure in the center of the emerging cyclone and on its outskirts becomes unequal: there, in the center of the cyclone, it is much lower, and a sharp pressure drop is the reason strong winds, which soon develop into hurricanes. In a space with a diameter of three hundred to five hundred kilometers, the strongest winds begin their frantic whirlwind.

Having arisen, cyclones begin to move at an average speed of 10-30 km / h, sometimes they can hover over the area for a while.

Cyclones (ordinary and tropical) are large-scale eddies with a diameter: ordinary from 1000 to 2000 km; tropical from 200 to 500 km and height from 2 to 20 km.

Air masses move in the area of ​​the cyclone in a spiral, twisting towards its center (counterclockwise in the northern hemisphere, vice versa in the southern) at a speed of:

Ordinary no more than 50-70 km / h;

Tropical 400-500 km/h

In the center of the cyclone, the air pressure is lower than at the periphery, which is why, moving in a spiral, the air masses tend to the center, where they then rise up, giving rise to strong clouds.

If in the center:

Normal cyclone air pressure compared to atmospheric (760 mm r.s.) is 713-720 mm r.s.;

Then in the center of a tropical cyclone, the pressure drops to 675 mm r.s.

At the center of a tropical cyclone there is an area of ​​low pressure with high temperature, with a diameter of 10-40 km, where calm reigns - typhoon eye.

Annually for globe At least 70 tropical cyclones arise and fully develop.

When a tropical cyclone (typhoon, hurricane) approaches the coast, it carries huge masses of water in front of it. Storm Shaft accompanied by strong rains And tornadoes. It swoops down on coastal areas, destroying everything in its path.

Example

In 1970, a typhoon. which broke through the mouth of the Ganges River (in India) flooded 800,000 km 2 of the coast. Had a wind speed of 200-250 m/s. Sea wave reached a height of 10 m. About 400,000 people died.

Today there are modern methods forecasting tropical cyclones (typhoons, hurricanes). Every suspicious cloud formation where it did not occur is photographed by meteorological satellites from space, weather service planes fly to the "eye of the typhoon" to get accurate data. This information is put into computers to calculate the path and duration of a tropical cyclone (typhoon, hurricane) and notify the population in advance of the danger.

Hurricane

A hurricane is a wind force of 12 points (up to 17 points) on the Beaufort scale, i.e. at a speed of 32.7 m/s (more than 105 km/h) and reaches up to 300 m/s (1194 km/h)

Hurricane- a strong small-scale atmospheric vortex in which the air rotates at a speed of up to 100 m/s. It is shaped like a pillar (sometimes with a concave axis of rotation) with funnel-shaped extensions at the top and bottom. The air rotates counterclockwise and simultaneously rises in a spiral, drawing in dust, water, and various objects. A hurricane on land is called storm and on the sea storm.

The main characteristics of hurricanes are:

Wind speed;

Ways of movement;

Dimensions and construction;

Average duration of actions.

most important characteristic hurricanes is wind speed. The table below (on the Beaufort scale) shows the dependence of the wind speed and the names of the modes. The average speed of a hurricane in Ukraine is 50-60 km/h.

Hurricanes vary greatly in size. Usually, the width of the zone of catastrophic destruction, which can be measured in hundreds of kilometers, is taken as its width. The hurricane front reaches a length of up to 500 km. Hurricanes occur at any time of the year, but are more frequent from July to October. In the remaining 8 months they are rare, their paths are short.

The average duration of a hurricane is 9-12 days. In Ukraine, hurricanes do not last long, from a few seconds to several hours.

A hurricane is almost always clearly visible; when it approaches, a strong hum is heard.

Hurricanes are one of the most powerful forces elements. In terms of their harmful effects, they are not inferior to such terrible natural disasters as earthquakes. This is due to the fact that they carry enormous energy. Its amount released by a hurricane of average power in one hour is equal to the energy nuclear explosion at 36 Mgt.

A hurricane carries a triple threat to people who find themselves in its path. The most destructive are wind, waves and rain.

Often, showers accompanied by a hurricane are much more dangerous than the hurricane itself, especially for those people who live on or near the coast. A hurricane creates waves up to 30 m high on the coast, can cause showers, and later cause an epidemic, for example, a hurricane storm tide, which coincided with the usual one, caused a giant flood on the coast of India in 1876, during which the wave rose by 12-13 m About 100,000 people drowned and almost as many died from the consequences of a ferocious epidemic.

When a hurricane propagates over the sea, it causes huge waves 10-12 meters or more high, damaging or even leading to the death of the ship.

The greatest danger during a hurricane is objects lifted from the ground and spun to great speed. Unlike storms, a hurricane travels in a narrow band, so it can be avoided. You just need to determine the direction of its movement and move in the opposite direction.

Hurricane wind destroys strong and demolishes light structures, devastates sown fields, breaks wires and knocks down power lines and communication poles, damages highways and bridges, breaks and uproots trees, damages and sinks ships, causes accidents on utility and energy networks in production . There were cases when hurricane winds destroyed dams and dams, which led to large floods, threw trains off the rails, tore bridges from supports, knocked down factory pipes, and threw ships onto land.