What is a cyclone? Tropical cyclone in the Southern Hemisphere. Cyclones and anticyclones - characteristics and names. Hurricanes What is a tropical hurricane

FAQ about tropical cyclones (hurricanes, typhoons)

1. What is a hurricane, typhoon and tropical cyclone?

Tropical cyclone is a term used for a non-frontal system low pressure synoptic and mesometeorological scale in tropical and subtropical waters, with organized convection and a certain cyclonic wind circulation. Hurricanes and typhoons are local names for tropical cyclones.

Tropical cyclones with a maximum wind speed near the earth's surface up to 17 m/s is called a tropical depression. It has closed circulation. Depressions arise as a result of wave disturbances in the intratropical convergence zone (ITC) on the tropical front, as well as on the trade winds. Weak wave disturbances also arise independently of the fronts inside the trade wind current. These tropical depressions move slowly, mainly from east to west, in the general direction of air transport within the tropics.

If the wind in a tropical cyclone blows at a speed of 17 to 33 m/s, then it is a tropical storm. Convection in it, as a rule, is concentrated in the center, and precipitation falls in distinct accumulations of Cb.

2. What are Cape Verde hurricanes? This is a type of Atlantic tropical cyclone that forms close to (less than 1000 km) from the Cape Verde Islands and then becomes hurricanes to the Caribbean. As a rule, such hurricanes occur in August and September. Their number varies from 0 to 5 per year - an average of 2 cases per year.

3. What is a "super typhoon"?

A super typhoon is a typhoon with wind speeds of 65 m/s or more.

4. What are the "Eastern waves" and what are the reasons for their occurrence?

It was noted that in the lower troposphere (from the surface of the ocean to a height of 5 km) there are so-called "easterly waves", which are the cause of a large number of tropical cyclones in the Atlantic. These waves originate in Africa. Various mechanisms for the formation of these waves have been proposed. They have been proven to be caused by the instability of the African east flows. (This is a baroclinic-barotropic instability - when the value of the potential eddy begins to decrease in the north direction.) These waves move in the western direction. w-w direction Atlantic. The first waves are noticeable in April-May and continue until November. The wavelength reaches 2500 km, and their period is 3-4 days. On average, about 60 waves are generated annually in North Africa. About 85% of active Atlantic hurricanes originate in an easterly wave.

5. What is a "tropical disturbance"?

Tropical disturbance is a separate weather system with clearly limited convection, 200-600 km in diameter, occurring in tropical or subtropical latitudes. It has a non-frontal migratory character. Keeps for 24 hours or more. It may or may not be associated with a noticeable perturbation of the wind field.

6. What is the maximum sustainable wind speed?

This maximum speed wind, measured in 1 minute at a height of 10 m from the surface. Wind speed in gusts will be 20 - 25% more.

7. What is a subtropical cyclone?

A subtropical cyclone is a low-pressure system found in tropical and subtropical latitudes (anywhere from the equator to 50°N) that has features of both tropical and extratropical cyclones. Many of these cyclones exist in regions with weak or moderate temperature gradients (like mid-latitude cyclones) but derive much of their energy from convective cloudiness (like tropical cyclones). The wind speed in these storms does not exceed 33 m/s. Often these cyclones transform into purely tropical ones.

8. Where do tropical cyclones originate and what are their paths?

Tropical cyclones originate over the oceans (North Atlantic tropical cyclones can occur over Africa, but the wind in them increases to a storm or hurricane already over the ocean) mainly in their western parts, in equatorial zone calm, but far enough from the equator (10-20 ° latitude), where the surface temperature of the water reaches 28? C. Once born, they begin to move west, slowly at first, and then faster and faster. After some time, the trajectory of the cyclones bends to the northwest, then to the north, and finally to the northeast. The point in the trajectory at which the movement of the cyclone changes from northwest to northeast is called the turning point.

9. What is the speed of the tropical cyclone itself and the air currents inside?

The forward speed of hurricanes and typhoons is different. Sometimes they stand still, though not for long, or move at a speed of several kilometers per hour, and then tens of kilometers. Figures of the order of 50-60 km / h can be considered average, the maximum advance is 150 - 200 km / h.

10. What is the lifetime of hurricanes?

The average duration of an Atlantic hurricane is about 9 days, and in August - about 12 days. The longest hurricanes exist, originating in Africa and in the region of the Cape Verde Islands, crossing the Atlantic Ocean twice and going far to the north. Their duration is 3 or 4 weeks. Sometimes tropical hurricanes, without losing strength, turn into extratropical hurricanes, and then their life span is enormous.

What are the main areas where tropical cyclones originate?

Tropical cyclones mainly occur in the following areas:
In the northern hemisphere:
1. The Yellow Sea, the Philippine Islands and the Pacific Ocean to the east of them up to 170°E. e. In this region, the largest number of tropical cyclones is observed in comparison with others: an average of 28 per year, of which about half have a hurricane wind force of 9-12 points.
In some years, there are up to 50 of them. Tropical cyclones in this area are locally called typhoons. Typhoons move first to the west and northwest. If they reach the coast of China at the same time, they quickly fade over land. But more often, before reaching the mainland, they turn to the northeast and at the same time often (in 15% of cases) pass through the southern Japanese islands or near them. Occasionally they can even reach the Kamchatka region.
2. Pacific Ocean west of Mexico. Here, on average, 6 tropical cyclones occur annually with storm and, relatively rarely, with hurricane winds.
3. The tropics of the North Atlantic Ocean, especially in the west of the ocean - in the Caribbean Sea, in the region of the Lesser Antilles and in the Gulf of Mexico - and in the east of the ocean - in the region of the Cape Verde Islands. Their local name is hurricanes. On average, 10 tropical cyclones occur annually over the North Atlantic Ocean.
Cyclones in the western part of the ocean often pass over the Greater Antilles. The strongest hurricane "Flora" passed over Cuba in October 1963. Sometimes they fall on the mainland in the area of ​​Florida and other southeastern US states. In other cases, cyclones, turning northeast over the ocean, may pass near the US Atlantic coast. Despite their relative rarity, hurricanes cause great losses to the US economy and do not do without loss of life.
4. Bay of Bengal. Here, on average, 6 cyclones occur per year. When they land on land in India, they often produce great havoc; the surges of water associated with them on flat shores are especially terrible.
5. Arabian Sea. Here, on average, less than two cyclones a year occur, as in the Bay of Bengal, in spring and autumn.
In the southern hemisphere:
1. The Pacific Ocean east of New Guinea and northern Australia (Queensland) to the Samoa Islands, and maybe further. The frequency here is 7 cyclones per year; hurricane-force cyclones are rare.
2. Indian Ocean between Madagascar and Mascarene Islands. There are an average of 7 cyclones per year.
3. Indian Ocean between the northwest coast of Australia and the Cocos Islands. Cyclones are very rare here - an average of 2 per year. The local name is vili-vili.
in the south Atlantic Ocean tropical cyclones of storm and hurricane force do not occur.
In total, about 120 tropical cyclones with storm and hurricane winds occur annually on the Earth. Their maximum, as a rule, occurs in the summer and autumn of the given hemisphere, when the tropical front is the most displaced from the equator. In winter they are almost non-existent.

12. What stages of evolution do tropical cyclones have?

A) the stage of formation. Tropical cyclones begin to form from a tropical disturbance. Its deepening occurs within a few days.

B) Stage of a young cyclone. The development of a tropical cyclone at this stage can go in two directions: either it moves in the form of a shallow depression for short distances and fades, or the cyclone intensifies, the pressure in its center drops below 1000 hPa, and a dense ring of hurricane-force winds arises around the center, with a radius of 40 - 60 km.

C) stage of maturity. At this stage, the pressure drop stops. The wind speed reaches a maximum and stops increasing. The radius of storm winds is also the largest. The zone of storm winds is located mainly on the right side of the cyclone. This stage can last from several hours to several days.

D) The stage of attenuation (dissipation). It starts when the cyclone makes landfall or cold weather. sea ​​current. At this stage, the existence of a hurricane can go in two directions: either it gradually fades, turning into a tropical depression, or it turns into a powerful extratropical cyclone on the polar front.

13. What are the dimensions of tropical cyclones?

Hurricanes vary greatly in size, and so do the ways in which they are assessed. Often, the width of the zone of catastrophic destruction - the zone of hurricane-force winds - is taken as the width of a hurricane. This zone has a width of 20 to 200 km or more. Often, a zone of storm-force winds with relatively little damage is added to this zone; then the width of the hurricane is measured in hundreds of kilometers, sometimes up to 1000 and even 1500 km. According to the latest data, Atlantic hurricanes have an average diameter of the hurricane wind zone of about 150 km, the diameter of the storm zone is 450-600 km. The size of typhoons is more significant. For the Pacific Ocean, the average size of the belt of strong winds accompanying the cyclone reaches 500–600 km. Smallest dimensions- about 80 km, the largest - 1600 km. Outside the tropics, they increase to 3000 km.

14. What is Storm Surge?

This is an anomalous rise in sea level associated with the passage of a strong tropical cyclone. The surge height is defined as the difference between the observed sea level during the cyclone and the normal sea level. It is also estimated by subtracting the normal sea level at high tide from that observed during the storm.

15. What is a CDO?

PCO is an acronym meaning "central dense overcast". This is a dense accumulation of cirrus clouds resulting from the formation of Cb anvils. (eye wall).

16. What is the "eye of the storm"? How is it formed and maintained?

The eye is the area at the center of a well-developed hurricane, characterized by light winds and clear weather without significant precipitation. Sometimes strong winds can spread into the eye. The eye has the lowest pressure. In the eye area, the highest air temperature is also observed: near the surface of the earth, it is only 0.5 - 2? C, but at an altitude of about 12 km it can be 10? C. The diameter of the eye is 30 - 60 km.

The eye is always surrounded by the so-called "eyewall" - the most dense ring of powerful Cb. This area always experiences the strongest wind and precipitation. In the eye, air descends and adiabatically heats up, and powerful upward movements occur in the wall of the eye. Convection in tropical cyclones is organized into long and narrow bands of powerful Cb (“rainbands”). Since these bands are arranged in a spiral, they are sometimes referred to as "spiral bands". Along these bands, the convergence is maximum at the lower level, and, therefore, the divergence is maximum at the upper level. Warm, moist air rises and then sinks on either side of the strip.

In some of the most intense cyclones, two or more concentric walls of the eye can be traced. That is, convection is organized in powerful cyclone rings.

17. What is the Moat in a hurricane?

The term "Ditch" usually refers to the area between the wall of the eye and the outer band Cb (see figure). The ditch is a region with comparatively little rainfall.

18. How do tropical cyclones form?

For a tropical cyclone to form, the following conditions are required at a given location:
- high water temperature (not less than 26.5°C) to a depth of about 50 m, contributing to the preservation of thunderstorms and convection;
- instability of the atmosphere (a sharp drop in air temperature with altitude), this contributes to the release of heat of condensation at altitude;
- relatively wet layer in the middle troposphere (at a height of up to 5 km); high humidity contributes to the further development of indignation;
- distance from the equator at least 500 km (the farther from the equator, the greater the Coriolis force, which plays a significant role in the formation of a hurricane);
- Pre-existing near-surface disturbance with sufficient rotation and convergence. Tropical cyclones cannot occur spontaneously;
- Low values ​​(less than 10 m/s) of vertical wind shear between the surface and the upper troposphere, as its large values ​​have a negative effect on the development of the cyclone.

But these conditions are not sufficient, so many perturbations do not develop further. Inside the IWC are often born warm whirlwinds. These mesovortices have horizontal dimensions of 100–200 km and are most powerful in the middle troposphere (about 5 km), and are not traced near the surface. Apparently, they make a huge contribution to the further evolution of the cyclone.

B>19. Why does a tropical cyclone require very warm water to form?

Tropical cyclones can be thought of as engines fueled by warm, moist air. This warm air cools as it rises and forms Cb in the form of streaks and walls of the hurricane's eye. When water vapor condenses into droplets, latent heat is released. In 1948, Eric Palmen found that for the development of a tropical cyclone, the temperature ocean waters should be at least 26.5? C to a depth of about 50 m. This value is associated with instability in the atmosphere in tropical latitudes. At a higher temperature, deep convection occurs, while at a lower value, the atmosphere is stable and therefore no thunderstorm activity (convection) occurs.

20. What is the Saharan Air Layer (SAL)?

The Saharan Air Layer is a layer of very dry and dusty air that forms over the Sahara from spring to autumn and usually moves from there towards the tropical Atlantic. SAL usually spreads at altitudes of 1500 - 6000 m. It contains a large amount of dust, has low humidity (less than 50%) and is accompanied by strong winds (10 - 25 m/s). SAL is known to negatively affect the intensity of tropical cyclones. Its dry air contributes to the weakening of the cyclone, because. prevents upward motions, and strong winds significantly increase the wind shear in the area of ​​the storm. The dust contained in this air also affects negatively. SALs can extend all the way to the Caribbean.

21. What is neutercane?

It is a small (less than 100 miles in diameter) low pressure system that has the characteristics of both a tropical and an extratropical cyclone. They differ from subtropical cyclones in their size and in that they sometimes form within the IWC.

22. Why top speed wind in hurricanes is observed on the right side in the northern hemisphere and on the left - in the southern?

The strongest winds in a hurricane have been proven to be on the right side of the hurricane because the movement of the hurricane also contributes to its circulating winds. In a hurricane with an average wind speed of 145 km/h, on its right side there will be winds at a speed of 160 km/h, and on its left side - 130 km/h when the storm moves forward at a speed of 16 km/h. For tropical cyclones of the Southern Hemisphere, everything will be the opposite - the maximum winds are observed on the left side of the hurricane, because. in the southern hemisphere, the rotation of a hurricane is clockwise.

23. How much energy does a hurricane produce?

The energy of a hurricane can be estimated in two ways:
a. As the total amount of energy received from the condensation of water vapor in a hurricane, or
b. As the amount of kinetic energy required to sustain strong winds in a hurricane.

There are 2 methods for estimating the total energy of a hurricane:
Method I: The total amount of energy released during the formation of clouds and precipitation.
A hurricane produces on average 15 mm of precipitation per day over an area equal to a circle with a radius of 665 km ( large quantity rainfall falls in the eye wall and in the rainbands). Converting this rainfall to volume gives about 2.1 x 10 16 cm3 per day. 1 cm 3 precipitation weighs 1 g. Using the latent heat of condensation, it is not difficult to calculate that this amount of rain formed gives about 5.2 x 10 19 J / day or 6.0 x 10 14 W of energy!!!
II method: the amount of kinetic energy (wind energy).

For a mature hurricane, the amount of kinetic energy produced is equal to this amount dissipated due to friction. Using a wind speed of 40 m/s over a distance of 60 km, we obtain a dissipation rate of about 1.3 x 10 17 J/day or 1.5 x 10 12 W of energy.

24. What are "Concentric eyewall cycles"?

This phenomenon occurs in intense tropical cyclones, corresponding to categories 3, 4 and 5 on the Saffir-Simpson scale with wind speeds over 185 km/h. Tropical cyclones reaching this category usually (but not always) have an eye wall and a maximum wind radius of 10 to 25 km. At this point, some of the outer rainbands may organize into an outer ring of thunderstorms (the outer wall of the eye), which slowly moves inward, depriving the inner wall of the eye of the necessary moisture and momentum. During this phase, the hurricane weakens (maximum winds decrease and pressure at the center increases) as the inner wall becomes "clamped" by the outer. As a result, the outer wall of the eye replaces the inner cavity and the hurricane resumes its intensity to its former, and sometimes stronger.

25. What time of year is the hurricane season in different parts of the world?

The Atlantic hurricane season officially runs from June 1 to November 30. Their maximum intensity falls on the first half of September.

The hurricane season in the Pacific Northeast officially runs from May 15 to November 30.

In the Pacific Northwest, tropical cyclones (typhoons) can develop throughout the year. Therefore, there is no official typhoon season here. But there is a small minimum of cyclonic activity in February - early March, and the main season lasts from July to November with a peak in late August - early September.

The North Indian Ocean has a double peak of cyclone activity - in May and November, but the season lasts from April to December. Strong tropical cyclones (more than 33 m/s) in this region occur mainly from April to June and from late September to early December. The southwest and southeast of the Indian Ocean have very similar annual cycles of cyclone activity, which begin in late October - early November, having 2 peaks of activity: in mid-January and late February - early March. The end of the season is celebrated in May.

In the southwestern Pacific Ocean, the tropical cyclone season begins in late October - early November, reaching a peak in late February - early March.

Globally, the most active month is September and the least active month is May.

26. Why are tropical cyclones very rare in the South Atlantic?

In March 2004, Hurricane DID formed in the South Atlantic and hit the coast of Brazil. It was only the second tropical cyclone in the last 60 years! The question remains why hurricanes are so rare in this region. Many see the relatively low surface temperature of the ocean as the reason for this, but the main reason is that there is strong vertical wind shear in the troposphere from the near-surface to 200 hPa in this region. The consequence of this is the lack of tropical zone convergence (ICT). And without the ETC, the appearance of large-scale synoptic eddies becomes practically impossible. However, there is documented evidence of a severe tropical depression that formed off the Congo coast in mid-April 1991. This storm lasted about 5 days and moved southwest to the center of the South Atlantic. However, no studies have been conducted regarding the conditions that accompanied this rare event.

27. What is the thunderstorm activity in tropical cyclones?

Oddly enough, in the interior of the hurricane (within 100 km from the center), lightning does not occur as often. And only about a dozen or less cloud-to-ground impacts per hour occur around the wall of the eye. However, at a distance of about 100 km around the storm, the number of flashes can be about 100 per hour. Such weak thunderstorm activity in the inner part of the hurricane is explained by some features of Cb. Updrafts are not well developed in the region where these Cb are formed. Due to weak updrafts, there is a lack of supercooled water in the wall of the eye, resulting in very weak thunderstorm activity. And more lightning in the outer part of the hurricane is associated with more convective rainbands. Black (1975) suggested that a sharp increase in convection within a cyclone, which is accompanied by an increase in thunderstorm activity, is indicative of the intensification of a hurricane. As it turned out later - most often this is true.

28. Why don't hurricanes occur near the equator?

Tropical cyclones are rarely observed closer than 5° latitude to the equator, since the deflecting force of the Earth's rotation here is too small for a strong cyclonic circulation to develop: the pressure differences arising here must quickly fill.

29. What is the "Explosive deepening of the cyclone"?

This is the pressure drop in a tropical cyclone at a rate of at least 2.5 mb/hr for at least 12 hours, or at a rate of at least 5 mb/hr for 6 hours.

What is the Fujihara Effect?

This is a phenomenon in which two or more closely spaced tropical cyclones rotate cyclonically around a common point (similar to binary systems in space). In this case, the distance between interacting cyclones should be no more than 1450 km. In the northern hemisphere this rotation is counterclockwise, and in the southern hemisphere it is clockwise. This phenomenon is most common in the North Pacific.

What are the signs of a hurricane passing through this point?

96 hours before eye appearance:
at first glance there are no signs of a storm. Atmosphere pressure stable, the wind is light and changeable. Separate cumulus clouds in the sky. But a diligent observer will notice bulges on the surface of the ocean, which every 10 seconds. fall on the shore in the form of waves, about 1 meter high. These waves generated by a hurricane can be easily masked by ordinary wind waves.

72 hours before eye appearance:
little has changed, except that the bulges have become about 2 meters high and crash onto the shore every 9 seconds. This means that the hurricane is still far below the horizon, but is gradually approaching.

48 hours before eye appearance:
The cumulus clouds are gone, the sky is clear, the pressure is stable, and the wind is calm. The bulges are already 3 meters high and go every 8 seconds. A command is given to evacuate densely populated areas.

36 hours before eye appearance:
The first signs of a hurricane. The pressure gradually drops, the wind speed is about 5 m/s, the bulges are already 4 m high and move apart every 7 seconds. A continuous mass of cirrus clouds appears on the horizon, which gradually covers most of the horizon.

30 hours before eye appearance:
The sky is overcast with clouds. The pressure drops at a rate of about 1 mb/hour, the wind has increased to 10 m/s. The bulge repeats after 5 seconds, small lambs begin to appear. A hurricane warning is issued and evacuations continue.

24 hours before eye appearance:
The sky is overcast and low fast moving clouds (Frnb) have appeared. The pressure drops by 2 mb/hour, the wind has increased to 15 m/s. There is a lot of foam and swelling on the sea. By this time, the evacuation should be completed and all preparations completed.

18 hours before eye appearance:
Low clouds are more powerful, bringing with them intermittent heavy rain, accompanied by gusty winds. The pressure continues to fall, the wind has increased to 20 m/s. Walking against the wind is difficult.

12 hours before eye appearance:
Charges of heavy rains are becoming more frequent, the wind is increasing to 33 m/s. Various objects and leaves fly through the air. The sea level is constantly rising. The pressure drops even faster.

6 hours before eye appearance:
It is raining continuously and the wind speed is 40 m/s or more. Because of this, the rain falls horizontally. The pressure drops very quickly. All kinds of objects fly in the air, all kinds of destruction occur, the storm surge increases. The surface of the sea is white.

1 hour before eye appearance:
The downpour pours in a continuous stream. The lowland areas are flooded from the rain. The pressure drops unimaginably. The wind speed is more than 45 m/s. Coastal roads are flooded, waves are over 5 m high. The toughest moment ever!

Eye:
After reaching its peak, the wind subsides, the precipitation stops suddenly and the sky begins to clear up. But the pressure continues to drop by 3 m/b per hour. Storm surge is greatest. The wind stops completely. The air is warm and humid. You can see clouds rising up to 14 km around, illuminated by the Sun. The pressure stopped for a while, and then began to rise rapidly. The wind became a little stronger and began to blow from the opposite side.

1 hour after eye appearance:
The sky darkened, the downpour and the wind became the same as 2 hours earlier. The storm surge has begun to decrease, but huge waves continue to crash on the shore. The pressure is growing at a rate of 2 mb/hour, the wind is over 45 m/s.

6 hours after eye appearance:
The downpour continues, but the wind has decreased to 40 m/s. The storm surge is receding, dragging various debris into the ocean.

12 hours after eye appearance:
It rains intermittently and the wind gradually decreases after each period of rain. The base of the clouds as the pressure rises. The wind speed still remains in the hurricane area - 30 m / s, and the ocean is covered with foam.

24 hours after eye appearance:
Low clouds break into small fragments. The pressure is growing at the same speed, the wind has decreased to 15 m/s. The storm wave has completely moved away from the shore, but the surface of the sea is still covered with white caps and foam.

36 hours after eye appearance:
The overcast disintegrated, the layer of cirrus clouds almost completely disappeared beyond the horizon. The sky has become clear, the pressure is growing slightly, the wind speed is about 5 m/s. Around the various destruction (depending on the category of the hurricane).

32. How is a hurricane formed?

The first stage in the formation of a hurricane is the appearance of accumulations of small thunderclouds in tropical latitudes (mesoscale convective complexes). These complexes (or clusters), which can eventually develop into a hurricane (typhoon), are called "Tropical Outrage" and is the first stage of cyclone development. A tropical disturbance (TV) is formed when trade winds converge in tropical latitudes. As a result, instability is created in the atmosphere, which is an impulse for the formation of a storm. This situation is created near the equator, where easterly winds converge, forming thunderstorm centers. This area is called the Intratropical Convergence Zone (ITC). But most Atlantic hurricanes form from another type of TV called "Eastern Waves". This wave causes a convergence of winds that intensify thunderstorm activity on the east side of the wave. TV is not traced on the synoptic map, because has no closed isobars.

TV enters the second phase of development, called "Tropical Depression" when the wind speed in it reaches 37 km / h. In a tropical depression (TD), pressure begins to drop slightly, and 1 closed isobar appears. Pressure begins to drop as the water vapor within the storm condenses, releasing the latent heat of condensation into the atmosphere. This addition of heat causes the atmospheric air to expand, so it becomes less dense inside the depression and rises up thousands of meters. At altitude, this air cools and the water vapor in it condenses, adding even more heat. As a result, even more air will rise upward, releasing even more heat as a result of condensation, etc. This process occurs like an avalanche, as a result of which the temperature inside the storm is constantly growing, so the atmospheric pressure in the center of the depression drops even lower. As pressure drops, ground air laden with water vapor is drawn inward, releasing even more heat at the center of the storm. As a result, the clouds are getting denser and the precipitation is getting stronger. Air cooled at altitude begins to sink around the depression, forcing even more humid air upwards. Thus, there is a closed circulation of air flows (see Fig.). As this cycle continues, the pressure at the center of TD drops even more, hence the surface wind speed is constantly increasing. And when it reaches 63 km / h, then the depression enters the third phase of development, which is called "Tropical Storm". At this moment, the eye of the storm begins to be traced, 2–3 closed isobars appear on the synoptic map. In this moment leading role the Coriolis force plays, which gives the storm a rotational (cyclonic) motion, and also determines the trajectory of its movement. This figure shows the effect of the Coriolis force on Hurricane Isabel in the Northern Hemisphere. The red arrows indicate the Coriolis force, the blue arrows indicate the gradient force, and the black arrows indicate air currents.

When the wind speed in a tropical storm reaches 119 km / h, it is officially considered a hurricane (typhoon).

The last stage of the existence of a hurricane is its dissipation (destruction).

SAFFIRE-SIMPSON SCALE

33. How does a tropical cyclone affect ocean surface temperature?

The passage of a tropical cyclone over the water surface often leads to a significant cooling of the ocean surface, which can subsequently affect the development of the cyclone. This cooling of the sea surface is caused mainly by the upwelling of cold water from deep in the ocean. Also, additional cooling is caused by the fall of a large amount of raindrops. Cloud cover may also play a role in ocean cooling by shielding the ocean surface from direct sunlight. The combination of these effects causes a sharp drop in sea surface temperature.

34. What is a hypercane?

A hyperhurricane is a hypothetical type of extreme tropical cyclone that could form if ocean surface temperatures reach about 50°C, which could be due to an asteroid or comet impact, volcanic eruptions, or rapid global warming. The term was coined by scientist Carrie Emmanuel of the Massachusetts University of Technology. in 1994.

According to calculations, the wind speed in the hyperhurricane will exceed 800 km / h, atmospheric pressure will be less than 700 hPa. The size of a hyperhurricane could be comparable to North America. It will cause storm surges 18 m high and its eye will be 322 km across. Hyperhurricane clouds will reach the middle stratosphere (up to 32 km). Because of this, it can destroy the ozone layer.

35. How is a tropical cyclone destroyed?

A tropical cyclone can cease to exist for several reasons. One of the main reasons is if it moves above the surface of the earth. In this case, the surface air is colder and, most importantly, less humid. Therefore, the “fuel” does not enter the hurricane and it begins to collapse. This is where its existence ends .. But sometimes a tropical cyclone can regenerate, entering a warm current. Also, the cyclone can die out if it remains practically motionless in one place, cooling the sea surface under it by more than 5 °C. In any case, a tropical cyclone either turns into a tropical depression, gradually eroding, or passes into an extratropical cyclone at the polar front.

36. What is the Stadium Effect?

This phenomenon is observed in fairly powerful cyclones. This phenomenon consists in the fact that the clouds of the wall of the eye are located at some inclination from the center with height. At the same time, the diameter of the eye at the top is much larger than at the surface, because. the air of the wall rises along isolines of equal angular momentum, which are also tilted outward from the eye and from a height it resembles a stadium. This phenomenon occurs more often in small eyes.

37. What is "Maximum Potential Intensity"?

Dr. Kerry Emmanuel created mathematical model around 1988 to calculate the ultimate tropical cyclone intensity based on sea surface temperature and vertical atmospheric profiles. This model does not account for vertical wind shear.

38. What is "CLIPER"?

This is a computer model for predicting the trajectory of a hurricane for 3 or 5 days. Until the late 1980s, this was the most accurate model. There is also r-CLIPER, a precipitation forecasting version.

Tropical cyclones, hurricanes, typhoons

A particularly dangerous natural phenomenon 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 energy of the explosion 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°. At higher latitudes, 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 are formed in the northern part of the tropical zone of the 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 the 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 categories.

This scale is used by almost all hurricane and typhoon watch centers. IN Lately 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

There are four stages in the life cycle of a tropical cyclone:

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 ​​lower water surface temperatures or when it transitions 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 in the church calendar, on the day of which a devastating hurricane fell on a large population center.

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. At the end of the XIX century. Australian meteorologist Clement Wragg began referring to tropical storms by female names. Since 1953, the US National Hurricane Center began to publish preliminary lists, according to which Atlantic tropical storms were named.

Until 1979, only female names were used in it. 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 weapons: strong wind, heavy seas, heavy rains, heavy hail, high waters, floods, landslides, landslides, erosion and processing of banks.

Hurricanes cause enormous damage to the coasts of North and South America, islands along their path. 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 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 each year appear over western part Pacific Ocean, the Sea of ​​Japan and Primorsky Krai, i.e. into the territory of Russia, go to various years from one to four typhoons, bringing a sharp deterioration in the 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, damaged 196 bridges and about 2000 km highways. 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.

What is a cyclone? Almost every person is interested in the weather - looks at forecasts, reports. At the same time, he often hears about cyclones and anticyclones. Most people know that these atmospheric phenomena are directly related to the weather outside the window. In this article we will try to understand what they are.

A cyclone is a low pressure area covered by a system of circular winds. Simply put, it is a grandiose flat atmospheric vortex. Moreover, the air in it moves in a spiral around the epicenter, gradually approaching it. The reason for this phenomenon is considered to be low pressure in the central part. Therefore, warm wet ones rush upward, rotating around the center of the cyclone (the eye). This causes the accumulation of high density clouds. Strong winds rage in this zone, the speed of which can reach 270 km / h. The rotation of the air is carried out counterclockwise with some swirling towards the center. In anticyclones, on the contrary, the air swirls clockwise. A tropical cyclone in the Southern Hemisphere works much the same way. However, the directions are reversed. Cyclones can reach different sizes. Their diameter can be very large - up to several thousand kilometers. For example, a large cyclone is able to cover the entire European continent. As a rule, these atmospheric phenomena are formed in certain geographical points. For example, the southern cyclone comes to Europe from the Balkans; regions of the Mediterranean, Black and Caspian Seas.

The mechanism of cyclone formation - the first phase

What is a cyclone and how does it form? On the fronts, that is, in the zones of contact between warm and cold air masses, cyclones arise and develop. This natural phenomenon is formed when a mass of cold polar air meets a mass of warm, moist air. At the same time, warm ones burst into an array of cold ones, forming in them something like a tongue. This is the beginning of the cyclone. Sliding relative to each other, these flows with different temperatures create a wave on the frontal surface, and, consequently, on the front line itself. It turns out a formation resembling an arc, turned by concavity towards warm air masses. Its segment, located in the front eastern part of the cyclone, is a warm front. The western part, which is located behind the atmospheric phenomenon, is a cold front. In the interval between them in the cyclone, there are often zones of good weather, which usually lasts only a few hours. Such a deflection of the front line is accompanied by a decrease in pressure at the top of the wave.

Cyclone evolution: second phase

The atmospheric cyclone continues to evolve further. The formed wave, moving, as a rule, to the east, northeast or southeast, is gradually deformed. Language warm air penetrates further to the north, forming a well-defined warm sector of the cyclone. In its front part, warm air masses float on colder and denser ones. As it rises, steam condenses and forms a powerful cumulonimbus cloud, which leads to precipitation (rain or snow) that lasts a long time. The width of the zone of such frontal precipitation is summer time about 300, and in winter - 400 km. At a distance of several hundred kilometers ahead of the warm front near the earth's surface, the air reaches a height of 10 km or more, at which moisture condenses to form ice crystals. White ones are formed from them. Therefore, it is from them that one can predict the approach of a warm front of a cyclone.

The third phase of the formation of an atmospheric phenomenon

Further characteristics of the cyclone. Humid warm air of the warm sector, passing over the colder surface of the Earth, forms low stratus clouds, fogs, and drizzle. After the passage of a warm front, a warm cloudy weather with southerly winds. Signs of this are often the appearance of haze and light fog. Then a cold front approaches. Cold air, passing along it, swims under warm air and displaces it upward. This leads to the formation of cumulonimbus clouds. They are the cause of showers, thunderstorms, which are accompanied by strong winds. The cold front precipitation zone is about 70 km wide. Over time, the back of the cyclone comes to replace. She brings strong winds, cumulus clouds and cool weather. Over time, cold air pushes warm air to the east. After that, clear weather sets in.

How Cyclones Form: The Fourth Phase

As the tongue of warm air penetrates into the mass of cool air, it becomes more and more surrounded by cold air masses, and is itself forced upward. This creates a zone in the center of the cyclone reduced pressure where the surrounding air masses go. In the Northern Hemisphere, under the influence of the rotation of the Earth, they turn counterclockwise. As mentioned above, southern cyclones have opposite directions of rotation of air masses. It is precisely due to the fact that the Earth turns around its axis that the winds are not directed towards the center of the atmospheric phenomenon, but go tangentially to the circle around it. As the cyclone develops, they intensify.

Fifth phase of cyclone evolution

Cool air moves faster in the atmosphere than warm air. Therefore, the cold front of the cyclone gradually merges with the warm one, forming the so-called occlusion front. The surface of the Earth no longer has a warm zone. Only cold air masses remain there.

Warm air rises, where it gradually cools and is released from moisture reserves that fall to the ground in the form of rain or snow. The difference between the temperature of cold and warm air is gradually leveled. At the same time, the cyclone begins to fade. However, there is no complete homogeneity in these air masses. Following this cyclone near the front on the ridge new wave the second one appears. These atmospheric phenomena always come in series, with each following somewhat south of the previous one. The height of the cyclone vortex often reaches the stratosphere, that is, it rises to a height of 9-12 km. Especially large ones can be found at altitudes of 20-25 km.

Cyclone speed

Cyclones are almost always in motion. Their speed of movement can be very different. However, it decreases as the atmospheric phenomenon ages. Most often they move at a speed of about 30-40 km / h, covering a distance of 1000-1500 km or more in 24 hours. Sometimes they move at a speed of 70-80 km per hour and even more, passing 1800-2000 km per day. At this rate, the cyclone that raged today in the region of England, in 24 hours may already be in the region of Leningrad or Belarus, provoking a sharp change in the weather. As the center of the atmospheric phenomenon approaches, the pressure drops. There are various names for cyclones and hurricanes. One of the most famous is Katrina, which caused serious damage to the United States.

atmospheric fronts

What are cyclones, we have already figured out. Next, we will talk about their structural components - atmospheric fronts. What causes the huge masses of moist air in a cyclone to rise high up? To answer this question, we first need to understand what the so-called atmospheric fronts. We have already said that warm tropical air moves from the equator to the poles and on its way meets cold air masses of temperate latitudes. Since the properties of warm and cool air differ sharply, it is natural that their arrays cannot immediately mix. At the meeting point of air masses different temperatures a clearly defined band appears - a transition zone between air fronts with different physical properties, which in meteorology is called the frontal surface. The zone separating the air masses of temperate and tropical latitudes is called the polar front. And the frontal surface between temperate and arctic latitudes is called arctic. Since the density of warm air masses is less than that of cold ones, the front is an inclined plane, which always inclines towards the cold massif at an extremely small angle to the surface. Cool air, as denser, when meeting with warm air, raises the latter up. When imagining a front between air masses, one must always keep in mind that this is an imaginary surface tilted above the ground. The line that is formed when this surface crosses the earth is marked on weather maps.

Typhoon

I wonder if there is anything in nature more beautiful than such a phenomenon as a typhoon? A clear calm sky over a well of walls created by a crazy whirlwind, pierced by zigzags of lightning, walls two Everests high? However, big trouble threatens anyone who ends up at the bottom of this well...

Originating in the equatorial latitudes, typhoons head west, and then (in the Northern Hemisphere) turn to the northwest, north, or northeast. Although each of them does not exactly follow the path of the other, most of them follow a curve that has the shape of a parabola. The speed of typhoons increases as they move northward. If near the equator and towards the west they move at a speed of only 17-20 km / h, then after turning to the northeast their speed can reach 100 km / h. However, there are times when, unexpectedly deceiving all forecasts and calculations, typhoons either stop completely or rush insanely forward.

eye of the hurricane

The eye is a bowl with convex walls of clouds, in which there is a relatively weak wind or complete calm. The sky is clear or partly cloudy. The pressure is 0.9 of the normal value. The eye of a typhoon can range in size from 5 to 200 km in diameter, depending on the stage of its development. In a young hurricane, the size of the eye is 35-55 km, while in a developed one it decreases to 18-30 km. As the typhoon fades, the eye grows again. The more clearly it is outlined, the more powerful the typhoon. In such hurricanes, the winds are stronger near the center. Closing all streams around the eye, the winds swirl at speeds up to 425 km/h, gradually slowing down as they move away from the center.

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 solar heat stored by it and the condensation of the vapors contained in it. 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 medium-strength cyclone releases approximately the same amount of energy as 500,000 atomic bombs with power dropped over Hiroshima. Atmospheric pressure in the center of the nascent 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 cause of 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, generating heavy 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.

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

Every year at least 70 tropical cyclones arise and fully develop on the globe.

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. The sea wave reached a height of 10 m. About 400,000 people died.

Today, there are modern methods for predicting 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 in order 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 of the 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.

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 claim many 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 caused to material values ​​can be conditionally divided into direct and indirect. Direct is the damage that manifests itself directly during 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, the 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.

biological significance 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 its maximum intensity. 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, having brought the ship on the crest of one of its giant waves, threw it on the sea 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 a large number of ships that were in the path of the cyclone were sunk.

On the night of November 13, 1970, an incredible typhoon hit the coastal regions of East Pakistan (since 1971 People's Republic Bangladesh). A powerful wave up to 8 m high, raised by the wind, passed over a chain of densely populated islands. It was a colossal wall of water, seething and churning, a huge billow of water that the ocean threw up. 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 44,000 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. The business center of Darwin has been turned into mountains of rubble and debris. 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 on September 11-12 and South Korea causing significant damage and flooding. 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 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 in Japanese island 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 Florida peninsular coast turned out 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, the Associated Press reported. As of September 23, almost 1,100 victims are already known, and another 1,250 people are missing. The largest number of victims is 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 the international community for help. In May 2004, the island had already suffered one of the worst floods in history, which killed about 2.5 thousand people.

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. According to information agencies, over the past few days this cyclone has 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, destructive floods, 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.