How do typhoons form?
Since mid-July 2006, typhoons such as "Bilis", "Gemei", "Paibian" and "Sangmei" have come one after another, causing serious damage to the lives and property of the people of our country. Huge loss. According to incomplete statistics in Guangdong and Guangxi provinces alone, more than 200 people died due to the disaster, more than 10 million people were affected, and direct economic losses were tens of billions of yuan. Many readers wrote to ask, what happened to the typhoon? Why do typhoons have so many names? Why are typhoons so powerful? To answer these questions, we combine authoritative information to answer them.
There are many theories about the origin of the name "Typhoon". It is generally believed that it evolved from the Cantonese word for "big wind", and some say that it evolved from the Hokkien word for "wind sieve". Some people think that the ancients were not clear about the origin of the typhoon and thought it blew from Taiwan, so it has " Typhoon" said.
Actually, a typhoon is a type of tropical cyclone. The so-called tropical cyclone refers to a strong atmospheric vortex that occurs in the tropical ocean. Its intensity is based on the maximum average wind speed near the center of the bottom layer. According to international regulations, the maximum wind force near the center is called a typhoon with a force of 12 or above (called a hurricane in the West Indies and the Atlantic area); a wind force of 10 to 11 is called a severe tropical storm; a wind force of 8 to 9 Those with winds of magnitude 6 to 7 are called tropical depressions.
As the "big brother" in the tropical cyclone family, typhoons have a horizontal range of about hundreds to thousands of kilometers, and a vertical range from the ground to the lower stratosphere. The maximum average wind speed near the bottom center of the typhoon is about 30 to 50 meters/second, and sometimes it can even exceed 80 meters/second. As it advances, typhoons rotate violently while moving forward at sea or onto land, causing disastrous weather such as strong winds, heavy rain, huge waves, and storm surges, causing great damage to marine ships and coastal towns.
The tropical ocean is the "home" of typhoons. Typhoons usually occur on the vast tropical warm ocean with a water temperature of 26°C to 27°C. There, the sea surface temperature is high, the water vapor content in the air is large, and heat is continuously released during the rising air convection. Under the action of the deflection force of the earth's rotation, a rotating warm-core air column is gradually formed, and eventually develops into a typhoon.
On average, about 45 typhoons occur in the global ocean every year. How are these typhoons named? Previously, the international community had been using the tropical cyclone numbering system. For example, Tropical Storm No. 9608 was the eighth tropical storm generated in 1996. When it continued to develop into a typhoon, it was called Typhoon No. 9608. However, naming tropical cyclones by numbers is not easy to remember and is not convenient for meteorological departments to provide early warning. Therefore, in 1998, the 31st Typhoon Committee of the International Meteorological Organization decided that from January 1, 2000, tropical cyclones appearing in the northwest Pacific and South China Sea will adopt a new naming method.
The Typhoon Committee has currently named 140 names, provided by 14 members from the Asia-Pacific region, including China, Vietnam, Japan, the United States, and Hong Kong, China. Each member contributed 10 names. The 140 names are divided into 10 groups of 14 in each group and used in sequence. The names contributed by each member have their own characteristics. The 10 typhoon names named by China are: Dragon King, Poseidon, Dianmu, Jade Rabbit, Wukong, Fengshen, Haima, Haiyan, Dujuan and Haitang.
The actual naming of typhoons is left to the Japan Meteorological Agency in the region. Whenever the Japan Meteorological Agency determines a tropical cyclone in the northwest Pacific or the South China Sea to have tropical storm intensity, it gives it a name based on the list and a 4-digit number. The first two digits in the number are the year, and the last two digits are the order in which tropical storms were generated in that year. For example, Tropical Storm No. 8 this year has a 4-digit number of 0608, which should be "Sangmei" according to the typhoon naming table. When "Sangmei" reaches typhoon intensity, it is called Typhoon No. 0608 "Sangmei".
Experts from the Central Meteorological Observatory believe that there are two main reasons why typhoons frequently "visit" the southeastern coast of my country this year: First, rising global temperatures can easily form cyclones, leading to an increase in extreme weather phenomena; second, this year's western Pacific Ocean The temperature is high and the air pressure is strong, causing typhoons to move westward and frequently land in coastal areas of my country.