What is a tropical cyclone?

Tropical cyclones include tropical depression, tropical storm, strong tropical storm, typhoon, strong typhoon and super typhoon.

Brief introduction of tropical cyclones:

Tropical cyclone is a low-pressure vortex that occurs on the surface of tropical or subtropical ocean, and it is a powerful and profound tropical weather system. That is, a mesoscale or synoptic warm cyclone generated on the tropical ocean surface. Typhoon is a kind of tropical cyclone. In China, tropical cyclones in the northwest Pacific and South China Sea are classified into six grades according to the maximum average wind speed near the bottom center, in which the wind force is 12 or above, which is collectively called typhoon.

Tropical cyclone is a heating cyclone system generated and developed in tropical waters. Tropical cyclones produced in the western Pacific Ocean, the northwest Pacific Ocean and its adjacent waters are called typhoons); ; Tropical cyclones produced in the Atlantic Ocean and the Eastern Pacific Ocean are called hurricanes); ; Tropical cyclones produced in the Indian Ocean and the South Pacific can be referred to as cyclone storms or cyclones for short.

In a broad sense, the definition of tropical cyclone does not require the intensity of cyclone, that is, tropical cyclone can be called tropical cyclone in a broad sense at any stage of its life history; Tropical cyclones in a narrow sense only include strong cyclones in the mature stage, and their intensity must exceed the minimum standard of cyclone classification system according to the maximum wind speed in the center.

For example, in the Atlantic Ocean, only cyclone systems with maximum wind speed exceeding 120km/h 1 min will be classified as strict tropical cyclones, that is, hurricanes, and heating cyclones below this standard will be classified as tropical depressions and tropical storms.

Concepts similar to tropical cyclones include subtropical cyclones and extratropical cyclones. As a difference, extratropical cyclone is a cold air cyclone existing in the middle and high latitudes, which can be generated on the ocean or land. In most cases, it is formed by the unstable development of baroclinic, accompanied by the appearance of front.

Subtropical cyclone is a weather system between tropical cyclone and temperate cyclone. Its mature form is close to tropical cyclone, but it has a cold core structure similar to temperate cyclone in dynamics.

As a connection, tropical cyclones may become temperate cyclones after entering the temperate ocean surface, and temperate cyclones can also become tropical cyclones in a few cases. A subtropical cyclone will be recognized as a tropical cyclone after it enters the tropical ocean surface and transforms into a warm core structure, but when it passes through the subtropical ocean surface, it will not be recognized as a subtropical cyclone as long as its warm core structure remains unchanged.

Tropical cyclones contain a lot of unstable energy and may become meteorological disasters. In the mature landing stage, tropical cyclones bring significant destructive strong winds, a lot of precipitation and secondary disasters such as storm surges and thunderstorms.

Tropical cyclones in the ocean are a great threat to the shipping industry. Modern operational weather forecast can identify and observe tropical cyclones through satellite remote sensing, and predict and warn their development and movement in combination with numerical weather forecast. The main members of the World Meteorological Organization will name tropical cyclones in various sea areas and release information to the public.