How many kinds of typhoon warning signals are there?

Typhoon warning signals are divided into four types, namely typhoon blue warning signal, typhoon yellow warning signal, typhoon orange warning signal and typhoon red warning signal. On August 16, 2004, China Meteorological Bureau issued "Trial Measures for Issuing Early Warning Signals of Sudden Meteorological Disasters", in which typhoon early warning signals are divided into four levels: blue, yellow, orange and red, but some provinces and cities classify them according to their own characteristics.

Typhoon is a kind of tropical cyclone. 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. In China, tropical cyclones in the South China Sea and the Northwest Pacific are classified into six grades according to the maximum average wind force near the center of the bottom layer, and the wind force near the center reaches 12 or above, which is collectively called typhoon.

Typhoons and hurricanes are tropical cyclones, but they happen in different places and have different names. In the western North Pacific, west of the international international date line, including the South China Sea and the East China Sea, it is called a typhoon, while in the Atlantic Ocean or the eastern North Pacific, it is called a hurricane, that is, it is called a hurricane in the United States, a typhoon in the Philippines, China and Japan, and a cyclone in the southern hemisphere. Different places, times and names.