Discussion on typhoon degeneration and other problems

Typhoons and hurricanes are both strong tropical cyclones generated on the surface of tropical oceans, but they are called differently. Tropical cyclones that occur in the western part of the North Pacific Ocean and west of the international international date line, including the South China Sea, are called typhoons. Tropical cyclones in the Atlantic Ocean or the eastern North Pacific Ocean are called hurricanes, which means hurricanes in the United States and typhoons in the Philippines, China, Japan and East Asia. It is called a whirlwind in the southern hemisphere.

Typhoons are often accompanied by strong winds and heavy rains. The wind rotates counterclockwise. Isobars and isotherms are approximately a set of concentric circles. The central air pressure is the highest and the temperature is the lowest.

(1) refers to the cyclone in the Asia-Pacific sea area. Example: the typhoon described in Joseph Conrad's novels;

(2) Tropical cyclones in Philippine or China waters;

Typhoon is formed because the tropical sea surface is directly exposed to the sun, which makes the sea water temperature rise, the sea water evaporates into steam, and the surrounding cold air flows in to replenish it, and then rises again. This cycle will eventually expand the whole airflow and form a "wind". Due to the vastness of the ocean, the diameter of air circulation is increasing, even several kilometers. Due to the high-speed rotation of the earth from west to east, there is friction between the air column and the surface. The closer to the equator, the greater the friction, which makes the steering column rotate counterclockwise. (The southern hemisphere rotates clockwise. ) Because the earth rotates fast, the air column can't keep up with the speed of the earth's rotation, so it forms a westward sense, which also forms the typhoon and typhoon path we are talking about now. The center of the typhoon is in the position where the wind direction is T-shaped. It is not difficult to judge the distance and direction of the wind center according to the wind direction and wind speed. Based on my 40-year observation of the trend of clouds before typhoon Lei, it is basically accurate to judge whether the typhoon passes through the local area. The accuracy has been predicted to local areas many times. When the maximum wind speed near the ground reaches or exceeds17.2m per second, we call it a typhoon. (The following does not represent my own editing)

Judging from the typhoon structure, such a behemoth must have unique conditions.

First of all, there must be a vast atmosphere with high temperature and high humidity. The temperature and humidity of the bottom atmosphere on the tropical ocean surface are mainly determined by the sea surface temperature, and typhoons can only form on the warm ocean surface where the sea surface temperature is higher than 26℃-27℃ and the sea surface temperature is higher than 26℃-27℃ within 60 meters.

Second, there should be an initial disturbance in which the lower atmosphere converges to the center and the upper atmosphere spreads outward. Moreover, the divergence of the upper layer must exceed the convergence of the lower layer in order to maintain enough updraft and continuously strengthen the disturbance of the lower layer;

3. The difference of vertical wind speed should not be too big, and the relative motion of the upper and lower air is very small, so that the latent heat released by water vapor condensation in the initial disturbance can be stored in the air column in the typhoon eye area, forming and strengthening the typhoon warm center structure;

Fourth, there must be enough geostrophic deflection, and the earth's rotation is conducive to the formation of cyclonic vortices. The geostrophic deflection force is close to zero near the equator and increases at the north and south poles. Typhoons basically occur on the ocean surface about 5 latitudes from the equator.

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The birthplace of typhoon

The source of typhoon is distributed in the vast low latitude ocean surface of the northwest Pacific Ocean. The tropical disturbance in the northwest Pacific intensified and developed to the initial position of typhoon, with a relatively concentrated zone in latitude and longitude. East-west, tropical disturbances developed into typhoons, which were relatively concentrated in four sea areas.

(1) Sea surface in the north-central South China Sea

(2) The waters east of the Philippine Islands and near the Ryukyu Islands.

(3) Sea surface near Mariana Islands

(4) Sea surface near Marshall Islands

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Classification of typhoons

I. Strong typhoon

Super typhoon: the maximum average wind speed near the center of the ground layer is ≥ 5 1.0m/s, that is, 16 or more.

Strong typhoon (STY): The maximum average wind speed near the bottom center is 4 1.5-50.9 m/s, which is 14- 15.

Typhoon (TY): the maximum average wind speed near the center of the ground floor is 32.7-4 1.4m/s, which is 12- 13.

Second, a weak typhoon

Severe tropical storm (STS): the maximum average wind speed near the bottom center is 24.5-32.6m/s, that is, wind10-1.

Tropical storm (TS): the maximum average wind speed near the bottom center 17.2-24.4m/s, that is, the wind force is 8-9.

Tropical depression (TD): the maximum average wind speed near the bottom center 10.8- 17. 1 m/s, that is, the wind force is 6-7.

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The path of typhoon

The direction and speed of typhoon movement depend on the force acting on the typhoon. Power is divided into internal force and external force. The internal force is the resultant force from north to west caused by the different geostrophic skewness caused by the latitude difference between north and south within the typhoon range. The larger the typhoon range, the stronger the wind speed and the greater the internal force. The external force is the force of the external environment flow field on the typhoon vortex, that is, the guiding force of the easterly belt of the basic airflow on the south side of the subtropical high in the northern hemisphere. Internal force mainly plays a role in the initial generation of typhoon, while external force is the leading force to manipulate the movement of typhoon, so typhoon basically moves from east to west. Due to the influence of the shape, position and intensity of subtropical high, the typhoon's moving path is not uniform and becomes diverse. Taking the typhoon moving path in the northwest Pacific as an example, there are three moving paths:

(1) The westward typhoon moved from the east of the Philippines to the west, crossed the South China Sea, and finally landed on Hainan Island in China or northern Vietnam. This route mostly occurs in 10- 1 1, and 2006 is a typical example;

(2) Landing type: The typhoon moved to the northwest, crossed the Taiwan Province Strait, landed in the coastal areas of Guangdong, Fujian and Zhejiang, and gradually weakened into a low pressure. This typhoon has the greatest impact on China. In recent years, the two typhoons "90 15" and "97 1 1" which have the greatest impact on Jiangsu belong to this type, and the paths from July to August are basically the same;

(3) Parabolic type: the typhoon moves to the northwest first. When approaching the eastern coast of China, turn to the northeast without landing and bypass Japan. The path is parabolic, mostly occurring in May-June and 9- 165438+ 10.

After the typhoon is formed, it will generally move out of the source and experience the evolution process of development, weakening and extinction. A mature typhoon has a circular vortex radius of 500 km ~ 1000 km and a height of 15 km ~ 20 km. Typhoon consists of three parts: peripheral area, maximum wind speed area and typhoon eye. The wind speed in the peripheral area increases from outside to inside, with spiral clouds and precipitation; The strongest precipitation occurs in the maximum wind speed area, with an average width of 8 km ~ 19 km, and there is a circular cloud wall between it and the typhoon eye; The typhoon eye is located in the center of the typhoon. The most common typhoon eye is round or oval, ranging in diameter from 10 km to 70 km, with an average of about 45km. The weather in typhoon eye is calm, partly cloudy, dry and warm.

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Several common abnormal paths in the northwest Pacific Ocean

According to the impact of abnormal typhoon paths on China, abnormal paths are usually divided into eight types:

(1) Typhoon in the Yellow Sea turned west: Its main feature is that the typhoon suddenly turned west when going north to the Yellow Sea near 125E, attacking the coasts of Liaoning, Shandong and Hebei provinces, and the normal path turned northeast in this area.

(2) The typhoon in the South China Sea turned northward: The main feature of this kind of typhoon is that it turned sharply to the northern part of the South China Sea, went northward along the meridian and attacked Guangdong head-on. The normal path is to move westward in the northern part of the South China Sea and land in western Guangdong, Hainan Island or Vietnam.

(3) Inverted parabola path: Inverted parabola is opposite to parabola path, turning to the west or southwest, and a few will land in East China. The normal path is that the parabola moves northwest or turns northeast.

(4) Cyclone path: When two typhoons are close enough, it is common to rotate counterclockwise in the Pacific Ocean, which tends to attract each other. Fujiwara experimented with this and pointed out their mutual attraction.

(5) Snake path: When the typhoon is advancing, it swings back and forth from left to right at the same time, showing a snake path. When forecasting, every swing may cause confusion in the prediction conclusion, or change the prediction conclusion with the actual situation.

(6) clockwise rotation: typhoon rotation is a way of its mutation. After rotation, it often chooses a new path to move, which makes the initial prediction fail. Clockwise rotation generally occurs in an environment where the basic flow field is weak.

(7) Counter-clockwise rotation: Some counter-clockwise rotation occurs in an environment where several basic air flows interact, which is different from the environment where the basic air flow is weak when rotating clockwise.

(8) High latitude frontal landing: This typhoon has been moving to the northwest since its formation, and landed in Korea and Liaoning, Shandong and other provinces in China. This path is stable, but the probability is very small. At the same longitude, this path is farther north 10- 15 latitude than the path that landed in East China.

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Number of typhoons

In China, the tropical depression with the maximum wind force of 8 near the center, which enters the west of east longitude 150 degrees and the north latitude 10 degrees, is numbered according to the order of occurrence every year. This is the "Typhoon X this year (tropical storm, strong tropical storm)" that we heard or saw on radio and television.

The number of typhoons is also the number of tropical cyclones. People want to number tropical cyclones, on the one hand, because a tropical cyclone often lasts for more than a week, and several tropical cyclones may appear in the ocean at the same time. With the serial number, there will be no confusion; On the other hand, the naming, definition, classification method and determination of the center position of tropical cyclones are different in different countries and methods, even in the same country, they are not exactly the same among different meteorological stations, which often leads to various misunderstandings and confusion in use.

Starting from 1959, China began to number tropical cyclones (tropical storms and above) that occur or enter the Pacific Ocean and the South China Sea north of the equator and west of the 180 meridian every year in order of occurrence. Offshore tropical cyclone. In the case of clear cloud structure and circulation, as long as the maximum average wind force near the center is above 7, it is also numbered. The serial number consists of four digits. The first two digits represent the year. The last two digits are the serial numbers of tropical cyclones above storm level in that year. For example, in 2003, Typhoon Du Fu 13, its serial number was O3 13. , representing the tropical cyclone with storm level 13 or above that occurred in 2003. Tropical depression and tropical disturbance are not numbered.

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Naming of typhoon

At the beginning of the 20th century, people began to name typhoons. It is said that the first person to name a typhoon was an Australian forecaster in the early 20th century. He named tropical cyclones as political figures he didn't like, so that meteorologists could call them publicly. In the northwest Pacific, the official naming of typhoons began with 1945. At first, only female names were used. Later, it is said that due to the opposition of feminists, starting from 1979, men's names and women's names were used alternately. Until 1997, 1 65438+1October 25th to 65438+February1,the 30th meeting of the Typhoon Committee of the World Meteorological Organization (WMO) held in Hong Kong decided that tropical cyclones in the northwest Pacific Ocean and the South China Sea should be named in Asian style, and it was decided that tropical cyclones in the year of 2000 should be named in the Asian style. The new naming method is to make a naming table in advance and then reuse it year after year in sequence. The naming table * * * has 140 names and is provided by 14 member countries and regions in the Asia-Pacific region to which WMO belongs, such as Cambodia, China, North Korea, Hong Kong, Japan, Laos, Macau, Malaysia, Micronesia, the Philippines, South Korea, Thailand, the United States and Vietnam. Each country or region provides 65,438+00 names. The 140 names are divided into 10 groups, and each group has 14 names. According to the alphabetical order of the English names of the member countries, it is recycled in turn, that is, the nomenclature table of tropical cyclones in the northwest Pacific Ocean and the South China Sea. At the same time, keep the original tropical cyclone number. Specifically, each name does not exceed 9 letters; Easy to pronounce; There is no bad meaning in each member's language; Will not bring any difficulties to members; Not the name of a commercial organization; All members should endorse the selected name. If any member objects, this name cannot be used as a typhoon name.

Browse the typhoon naming table. Names are rarely used, mostly animals, plants, food and so on. There are also some names that are adjectives or beautiful legends, such as Yutu and Wukong. The name "Rhododendron" was provided by China, which is the familiar Rhododendron: "Korowang" that landed in China a while ago was provided by Cambodia, which is the name of a tree: "Morak" was provided by Thailand, which means jade; "Ibudu" is a name provided by the Philippines, which means chimney or water pipe to discharge rainwater from the roof into the ditch.

The actual naming and use of typhoons is the responsibility of Tokyo Regional Professional Meteorological Center of Japan Meteorological Agency. When a tropical cyclone in the northwest Pacific or the South China Sea is determined by the Japan Meteorological Agency as a tropical storm intensity, it will be named according to the list and given a four-digit number. The first two digits of the number are the year, and the last two digits are the order of tropical storms in that year. For example, Tropical Storm No.4 in 0704 and 07.

According to the regulations, a tropical cyclone's name will remain unchanged throughout its life cycle, whether it is strengthened or weakened. For example, tropical storm 0704, severe tropical storm and typhoon were named "Wanyi" in English and "Iman" in Chinese. In order to avoid unnecessary confusion caused by multiple translators, the Central Meteorological Observatory in China, the Hong Kong Observatory and the Geophysical and Meteorological Observatory in Macau, China decided on a unified set of Chinese translations.

Under normal circumstances, the pre-made naming table is recycled year after year in sequence, but under special circumstances, the naming table will also be adjusted. For example, when a typhoon is notorious for causing particularly serious disasters or casualties, it becomes a well-known typhoon. In order to prevent it from having the same name as other typhoons, members of the Typhoon Committee may apply to delete its name from the naming list, that is, the name will be given to the tropical cyclone forever, and other tropical cyclones will no longer use it. When the name of a typhoon is deleted from the name list, the Typhoon Committee will supplement the name of a tropical cyclone according to the suggestions of relevant members.

From June 5438+1 October1in 2000, when the Central Meteorological Observatory issued the tropical cyclone warning, it used not only the tropical cyclone number, but also the tropical cyclone name. Previously, China has been using tropical cyclone numbering method.

Typhoons that have been removed from the list at present.

In 2006/KOOC-0/Strong typhoon "Canzhu" caused a total of/KOOC-0/04 deaths and lost/KOOC-0/200 million US dollars.

In 2006, the No.4 tropical storm "Billis" caused 672 deaths and 4.4 billion US dollars in losses in the Philippines, Taiwan Province Province and southeastern China.

In 2006, the No.8 super typhoon "Sang Mei" killed 458 people in the Mariana Islands, the Philippines, the southeast coast of China and Taiwan Province Province, resulting in economic losses of 2.5 billion US dollars.

In 2006, the 16 strong typhoon "Sang Na" killed 279 people in the Philippines, Hainan, Vietnam, Cambodia, Thailand and other countries, with economic losses of 747 million US dollars.

In 2006, the No.22 super typhoon "Durian" caused 8 19 deaths in the Philippines, Vietnam and Thailand, and the economic losses were incalculable.

In 2005, the No.9 strong typhoon "Mai Sha" (Metsa) caused great losses in East China.

In 2005, the super typhoon "Navi" (14) killed 2 1 person in Japan.

In 2005, the super typhoon "Wang Long" (19) caused heavy storms in Taiwan Province, Fujian, Guangdong and Jiangxi provinces, and caused some casualties.

Typhoon Tingting on August 8, 2004 killed three people, injured many others and caused some natural disasters in Nanniao Island, Japan.

In 2004, 14 strong typhoon "Rennes" caused heavy casualties along the eastern coast of China.

In 2003, the No.7 super typhoon Imoto caused heavy casualties in the Philippines and South China.

In 2003 13, the strong typhoon "Du Fu" caused huge disasters and property losses in South China.

In 2003, super typhoon Ma Mei (14) caused more than 150 deaths in South Korea.

In 2002, the No.6 strong typhoon "Chatan" landed in the Kanto Plain of Japan, causing many deaths and serious property losses.

Typhoon Pongsona in 2002 caused a lot of casualties and property losses in Guam.

Tropical Storm Wami on 26/200 1 was not very strong, but it was the typhoon closest to the equator, so it was removed from the list.

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Advantages and disadvantages of typhoon

In addition to bringing serious disasters such as storms to the landing areas, typhoons also have certain benefits.

According to statistics, the typhoon rainfall in Southeast Asian countries, including China and the United States, accounts for more than 1/4 of the total rainfall in these areas, so without typhoons, the agricultural difficulties in these countries would be unimaginable; In addition, typhoons play an important role in regulating the earth's heat and maintaining the heat balance. As we all know, tropical areas receive the most solar radiation heat, so the climate is also the hottest, while cold areas are just the opposite. Due to the activity of typhoon, the heat in tropical areas is dispersed to high latitudes, which compensates the heat in cold areas. If there is no typhoon, the climate in tropical areas will get hotter and hotter, while in cold areas it will get colder and colder, and the temperate zone on the natural earth will no longer exist, and many animals and plants will become extinct because it is difficult to adapt. This will be a very terrible scene.

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The disaster of typhoon

Typhoon is a very destructive and disastrous weather system, but sometimes it can also play a beneficial role in eliminating drought. Its harmfulness mainly includes three aspects:

(1) Strong wind. The maximum wind force near the typhoon center is generally above 8.

② Heavy rain. Typhoon is one of the strongest rainstorm weather systems. Generally, it can produce rainfall of 150 mm ~ 300 mm in the area it passes through, and a few typhoons can produce torrential rain above1000 mm. The rainstorm caused by typhoon 1975 in the upper reaches of Huaihe River created the extreme value of rainstorm in Chinese mainland and caused the "75.8" flood in Henan.

③ Storm surge. Generally, typhoons will increase water in coastal waters, and the maximum water increase in coastal areas of Jiangsu Province can reach 3m. Typhoon "9608" and "97 1 1" increased water, which made Jiangsu's coastal areas along the Yangtze River have a super-historical climax.

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Prevention and control of typhoon

Strengthening the monitoring and forecasting of typhoons is an important measure to reduce typhoon disasters. Meteorological satellites are mainly used to detect typhoons. The existence and size of the typhoon can be clearly seen on the satellite cloud picture. Using meteorological satellite data, we can determine the location of typhoon center, estimate the intensity of typhoon, monitor the direction and speed of typhoon movement, and the area where severe storms occur, which plays a key role in preventing and mitigating typhoon disasters. When the typhoon reaches the offshore, the radar can also detect it. There are also forecasters of meteorological stations, who, based on all kinds of information obtained, analyze the trend of typhoons, the place and time of landing, issue typhoon forecasts, typhoon emergency reports or emergency warnings in time, serve the public through television, radio and other media, and provide decision-making basis for governments at all levels. Issuing typhoon forecast or emergency report is an important measure to reduce typhoon disaster.

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Structure and energy of typhoon

At the lower level, typhoons mainly flow into low-pressure inflow. Because of the angular momentum balance, the inner region can produce strong wind speed, and the outflow airflow of anticyclone is in the upper layer. Strong upward movement connects the upper and lower circulation, which is the main feature of typhoon circulation. The hottest temperature in a typhoon is caused by the sinking movement, which occurs at the inner edge of the eye wall, where there is the strongest sinking movement. Convergence is strongest at the maximum wind speed radius in the lower layer of typhoon, and the maximum wind speed radius does not change much with height, which is located in the eye wall. In addition, the asymmetry of typhoon structure is also a feature that people pay attention to this year. The analysis shows that there is obvious asymmetry in the inner and outer areas of the typhoon, which plays an important role in the development of the typhoon and the transportation of momentum and kinetic energy. Weather-scale typhoon is a powerful dynamic energy source in the atmosphere, so it should have an important impact on the change and maintenance of atmospheric circulation in terms of energy, which has attracted people's attention. On the issue of energy, it was also pointed out this year that the horizontal vortex transport of angular momentum is very important outside typhoons; In addition, the generation and transport of momentum in the outer region is also very important, which should not be ignored in the typhoon energy budget. These are all related to the asymmetry of the typhoon.

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The origin of the word "typhoon"

Research on Technical Terminology published Wang Cunzhong's article The Origin and Naming Principles of Typhoon Terminology in Volume 8, No.2, 2006. This paper discusses the historical evolution of the word "typhoon". The author thinks that in ancient times, typhoons were called hurricanes, and the name "Mao Feng" (1956, simplified as typhoon) didn't begin to be used until the late Ming and early Qing dynasties, and the meaning of hurricanes became a general term for cold wave gale or non-typhoon gale. There are two theories about the origin of typhoon. The first category is "tone sandhi theory", which includes three types: one is the evolution from Cantonese "gale"; Second, it evolved from the "wind screen" in Minnan dialect; Third, during the Dutch occupation of Taiwan Province Province, it was named after Typhoon Taifeng, a character in the Greek theocracy epic. The second category is "origin theory", that is, naming a typhoon according to its origin. Because Taiwan Province Province is located in the Pacific Ocean and the South China Sea, most typhoons enter the mainland through the Taiwan Province Strait. Seen from the mainland, this kind of storm comes from Taiwan Province Province and is naturally called a typhoon. Because of the ideographic nature of Chinese characters, Taiwanese dialect is composed of Taiwan Province dialect and Feng characters.

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How to judge whether the typhoon is far away?

When the typhoon strikes, the wind blows hard and the rain stops suddenly. Does this mean that the typhoon is far away?

When the storm suddenly stops, it should be a phenomenon that the typhoon eye passes by. Generally speaking, after 20 or 30 minutes, the storm will come again, so you must not think that the typhoon is still far away, because when the typhoon leaves, the storm will usually gradually weaken and will not stop suddenly.

When the wind and rain suddenly stop, it may be the phenomenon of entering the eye of the typhoon, rather than the typhoon being far away, and the storm will suddenly strike again in a short time. After that, the wind and rain gradually decreased and became intermittent rainfall. Slowly, the wind died down, the clouds rose, and the rain gradually stopped. This is when the typhoon leaves. If the eye of the typhoon does not pass through the local area, but the wind direction gradually changes from north to south, the wind and rain gradually decrease, the air pressure gradually rises, the clouds gradually dissipate, and the weather turns better, which also means that the typhoon is moving away from China.

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Why can we determine the direction of the wind center according to the wind direction?

The horizontal range of a typhoon is generally elliptical. The diameter of typhoons that affect China's coastal areas in summer and autumn is mostly above 1000 km. In such a large horizontal range, the wind direction distribution in various places is very regular. Because the typhoon has a low pressure, its central pressure is the lowest; When the air is concentrated from all directions to the typhoon center, it will be affected by the rotation of the earth, so the wind direction will deflect at a certain angle. This deflection causes the horizontal wind direction of typhoons in the northern hemisphere, which always blows counterclockwise from all directions to the center. So the wind direction is different in every place in the typhoon area, but there is a certain wind direction somewhere. In addition, in the typhoon area, the closer the typhoon center is, the denser the air is, and the wind direction there is almost moving around the center of the typhoon, so the deviation angle of the wind direction pointing counterclockwise to the center (that is, the angle between the wind direction and the circumferential tangent) is also small; The farther away from the typhoon center, the greater the deflection angle. At the same time, the closer to the typhoon center, the greater the wind; The farther away from the typhoon center, the smaller the wind. So no matter where you stand in the typhoon area, as long as you stand in the lee, the center of the typhoon must be within 45 ~ 90 degrees on your left.

As we know, the wind direction in typhoon area and the direction of typhoon movement are two completely different concepts. Typhoons are mobile, for example, typhoons that affect China's coastal areas mostly move from the southeast; When its center is still in the waters north of Ryukyu Islands, its northwest edge may have reached Shanghai. At this time, Shanghai will not blow southeast wind because the typhoon moves eastward. From the wind direction distribution map of typhoon area, we can know that it is northerly wind. At this time, if you stand in the position facing south, the typhoon center is within 45 degrees on your left, which is the southeast direction of the typhoon moving towards China.