What is a tropical cyclone? What are the causes 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. Tropical cyclones usually form in tropical areas (such as the northwest Pacific Ocean, the North Atlantic Ocean and the Indian Ocean) 3-5 latitudes away from the equator. Their movements are mainly influenced by Coriolis force and other large-scale weather systems, and eventually dissipate at sea, or degenerate into extratropical cyclones, or dissipate after landing. Tropical cyclones landing on land will bring serious property and casualties, which is a natural disaster. However, tropical cyclones are also part of the atmospheric circulation, which can bring the heat energy and angular momentum of the earth's rotation from the equatorial region to a higher latitude; In addition, it can bring abundant rain to the coastal areas that have been dry for a long time.

The sea is very hot by the sun, and a lot of water vapor evaporates, rises and gathers in the air, and condenses and releases a lot of heat in the air. As energy, under the action of geostrophic bias, it drives the whole water vapor cloud to rotate, and then more water vapor evaporates, condenses and dissipates heat, rotating faster and faster, and heat continues to promote rotation and movement. In the process of rotation, the air flow in the central area is thrown around, the air flow is less and less, and the air pressure is lower and lower. Finally, a tropical cyclone forms and starts to move, which is a typhoon.