What does a typhoon mean?

Typhoon refers to a tropical cyclone that occurs in the western Pacific Ocean and the South China Sea. This is an extremely strong storm. The maximum wind force near the center can reach more than 12, accompanied by heavy rain.

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 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. Typhoons often bring strong winds, heavy rains and storm surges, causing serious disasters in the coastal areas of China.

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. If the typhoon is cut horizontally, we can see that there are three obviously different areas, from the center to the outside: typhoon eye area, cloud wall area and spiral rain belt area.

Introduction of typhoon formation conditions;

First of all, the tropical ocean surface is wide enough, which requires not only the surface temperature of seawater to be higher than 26.5 degrees Celsius, but also a layer of seawater with a depth of 60 meters, and the water temperature should exceed this value. Because the friction between air molecules in typhoon consumes huge energy, which can only be supplied by the latent heat released in the vast tropical ocean.

In addition, there will be strong winds around tropical cyclones, which will cause seawater to churn around the center. In the typhoon center where the air pressure drops very low, it can even cause the sea surface to swell up and then spread around, so the sea water will churn around the typhoon center.

In a typhoon, this sea churning will affect the depth of 60 meters. On the ocean surface where the seawater temperature is lower than 26.5℃, it is difficult to maintain the typhoon due to the lack of thermal energy. Therefore, in order to ensure that the sea surface temperature is always above 26.5℃ during this tumbling process, this warm water layer must have a thickness of about 60 meters.

Secondly, there will be a weak tropical vortex before the typhoon forms. The typhoon's energy comes from the water vapor in the tropical ocean. In this pre-existing tropical vortex, the internal air pressure is lower than the surrounding air pressure, and the surrounding air carries a lot of water vapor to the center of the vortex and moves upward in the vortex area. Wet air rises and water vapor condenses, releasing huge latent heat of condensation, which can make typhoons run.