What kind of weather system is a typhoon?

Typhoon is actually a strong tropical cyclone. Tropical cyclone is a strong weather system that occurs in tropical ocean. Like a vortex moving forward in a flowing river, it rotates rapidly around the center and moves forward with the surrounding atmosphere. Like temperate cyclones, the airflow in tropical cyclones in the northern hemisphere rotates counterclockwise around the center, while in the southern hemisphere it is the opposite. The closer to the tropical cyclone center, the lower the air pressure and the stronger the wind. However, tropical cyclones with strong development, such as typhoons, have a calm and clear sky area at their center, that is, the typhoon eye.

The intensity of tropical cyclones occurring in tropical oceans varies greatly. Before 1989, the tropical cyclone with the maximum wind force of 8 or above near the center was called typhoon in China, and the tropical cyclone with the maximum wind force of 12 near the center was called strong typhoon. Since 1989, China has also adopted international classification standards, that is, when the maximum wind force near the center of a tropical cyclone is less than 8, it is called a tropical depression, and the winds of 8 and 9 are called tropical storms, and the winds of 10 and1are strong tropical storms. Only the tropical cyclone with the strongest wind near the center is called a typhoon.

From the above definition, it is not difficult to see that tropical cyclone is a general term for tropical depression, tropical storm, strong tropical storm and typhoon. However, due to the weak destructive power of tropical depression, traditional tropical cyclones generally do not include tropical depression.

The generation and development of tropical cyclones need huge energy, so they are formed on the tropical ocean surface with suitable meteorological conditions such as high temperature and high humidity. According to statistics, tropical cyclones are generated in tropical oceans all over the world except the South Atlantic.

Most tropical depressions cannot develop into tropical storms, and only a certain number of tropical storms can develop into typhoon intensity. The intensity of typhoons also varies greatly. Some typhoons have a maximum wind speed of 35 m/s near the strong wind center, but typhoons with a maximum wind speed of more than 50 m/s near the center are not uncommon. For example, Typhoon 94 17 landed in Ruian, Zhejiang Province, and the maximum wind speed near its center reached 45 m/s when it landed.

The life history of tropical cyclones can be divided into three stages: generation, maturity and extinction. Its life span can generally reach more than one week, and some tropical cyclones can survive for more than two weeks under favorable external environment. When tropical cyclones land or move northward to higher latitudes, they will soon become extinct because they lose the high temperature and high humidity conditions on which they depend.