What is a typhoon? What areas of China do typhoons generally affect?

Typhoon is a kind of tropical cyclone. In meteorology, according to the definition of the World Meteorological Organization, a tropical cyclone with a sustained wind speed of 12 (that is, more than 32.7 meters per second) is called a hurricane or a local synonym, and the name of a hurricane is used in the North Atlantic and the East Pacific; Typhoon is a synonym for the western North Pacific (north of the equator, west of international date line, east of east longitude 100).

Due to the influence of the shape, position and intensity of subtropical high, the moving path of typhoon is not uniform, but diverse. Take the typhoon moving path in the western North Pacific as an example. Generally, 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 type of 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.

(3) Parabolic type: The typhoon first moves to the northwest. 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 generally 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. In the peripheral areas, the wind speed increases from the outside to the inside, with spiral clouds and staged 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, with a diameter of about 10km-70km and an average of about 45km. The weather in typhoon eye is calm, partly cloudy, dry and warm.