Severe tropical storm level

How many levels are there in severe tropical storms?

When the maximum wind force near the center is l0- 1 1, it is called a strong tropical storm. Typhoon and hurricane are both a kind of wind, but they happen in different places and have different names. The typhoon is in the western part of the North Pacific Ocean, west of the international date, including the South China Sea; 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.

Typhoon is a strong tropical cyclone generated on the surface of tropical ocean. 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.

Typhoon paths can be roughly divided into three categories: ① Westward typhoons move from the east to the west of the Philippines, cross the South China Sea, and finally land on Hainan Island in China or northern Vietnam. (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. (3) Parabolic type: The typhoon moves to the northwest first, then turns to the northeast when approaching the eastern coast of China, and turns to the vicinity of Japan, with a parabolic path.

Typhoon disaster

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 of150 mm-1000 mm in its passing area, and a few typhoons can produce heavy rain above1000 mm. The torrential rain caused by Typhoon No.3 in the upper reaches of Huaihe River 1975 created the extreme 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.

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.

China numbered the tropical depressions that entered the west of l50 degrees east longitude and the north of l0 degrees north latitude. The winds near the center were strong and reached magnitude 8, which were arranged in the order of annual occurrence. 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 indicate the year. The last two digits are the serial numbers of tropical cyclones above storm level in that year. For example, last year's typhoon Du Fu (13) numbered O3 13. , indicating the tropical cyclone with storm level 13 or above that occurred in 2003. Tropical depression and tropical disturbance are not numbered.