Is the direction of typhoon activity clockwise or counterclockwise in the northern hemisphere? What about the southern hemisphere? What about the equator?

Because of the geostrophic force, that is, Coriolis force, typhoons in the northern hemisphere rotate counterclockwise and typhoons in the southern hemisphere rotate clockwise. There is no typhoon at the equator, because it is impossible for a typhoon to form near the equator.

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 divided into six grades according to the maximum average wind speed near the center of the bottom layer, and those whose wind reaches 12 or above are collectively called typhoons. ?

Broadly speaking, the word "typhoon" is not the intensity of tropical cyclones. Tropical cyclones (including tropical storms, severe tropical storms and typhoons defined by the World Meteorological Organization) with sustained wind speeds of17.2m per second are called typhoons. On informal occasions, "typhoon" even directly refers to the tropical cyclone itself. When the tropical cyclone in the northwest Pacific reaches the intensity of tropical storm, the name is provided by the Typhoon Committee of the World Meteorological Organization 14 countries and regions. ?

According to the statistics of the United States Navy Joint Typhoon Warning Center, the number of typhoons in the Northwest Pacific and South China Sea in 1959-2004 is related to the month, with an average of 26.5 typhoons generated each year. The month with the most typhoons is August in Gregorian calendar, followed by July and September.

In July 2020, there was no typhoon in the Pacific Northwest and South China Sea, which was the first "empty station" in July since China 1949.

Extended data

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 bottom center, in which the wind force is 12 or above, which is collectively called "typhoon". Typhoon can be divided into general typhoon (maximum wind 12 ~ 13), strong typhoon (maximum wind 14 ~ 15) and super typhoon (maximum wind ≥ 16).

Typhoon is a deep low-pressure system, and its central air pressure is very low. There is an air flow converging towards the center at the lower level, and the air flow at the upper level mainly diverges outward. The structure of typhoon is divided into typhoon eye area, cloud wall area and spiral rain belt area from center to outside.