How did the typhoon come into being, how did it end, why did it move, change its course and turn?

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 and Japan.

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 lowest and the temperature is the highest.

Formation of typhoon

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. The typhoon occurred on the ocean surface about 5 latitudes from the equator.

Classification of typhoons

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

Strong typhoon (STY): The maximum average wind speed near the bottom center is 41.5-50.9m/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.

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.

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. The two typhoons "90 15" and "97 1 1" which have had the greatest impact on Jiangsu in recent years belong to this type, and basically follow this path from July to August.

(3) Parabolic type: the typhoon first moves to the northwest, turns to the northeast when approaching the eastern coast of China, and turns to the vicinity of Japan. The path is parabolic, mostly occurring in May-June and 9-165438+1October.

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 5 OOKM ~ 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.

Number of typhoons

China numbered the tropical depressions that entered the west of l50 degrees east longitude and the north of l0 degrees north latitude, and the maximum wind force near the center was 8, according to the sequence 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 the tropical cyclones (tropical storms and above) that occur or enter the Pacific Ocean and South China Sea north of the equator and west of 180 degrees east longitude every year according to the sequence of their 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.

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 are all called Manyi in English and Manyi 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.

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.