Mature tropical cyclones, in the middle of the deep cloud area, often have a clear and semi-cloudy area with a diameter of dozens of kilometers, which is called typhoon eye. On the satellite cloud image, the eye area appears as a big black spot near the center of the dense cloud area. The annular cloud area around the eye area is called cloud wall or eye wall.
The eye area is usually round, but it is also oval or irregular. In the early stage of tropical cyclone development, the eye area is generally irregular and has a large range. However, when the tropical cyclone develops strongly, the eye area shrinks into a circle and is axisymmetric.
Reasons for the formation of typhoon eye:
From the photos taken by meteorological satellites, it can be seen that the upper and middle layers of typhoons are generally circular, containing spiral clouds, which rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. Sometimes the cloudless typhoon eye can be clearly seen in the central part, and the rotation of clouds can represent the wind direction.
Inside the typhoon, it can be seen from the observation results of the meteorological reconnaissance plane flying into the typhoon from different heights and directions that the typhoon is generally a cloud column with a very large radius, and its height has been observed to be more than18km. The central part of this huge cloud column, Wan Li, is cloudless or thin, and there is no wind and rain. This is the eye of the typhoon.
Seen from the typhoon, just leaving the eye of typhoon, the clouds are thickest and the wind and rain are heaviest. Gradually outward, the clouds are getting higher and thinner, and the wind and rain are getting weaker.
Refer to the above? Baidu encyclopedia-typhoon eye