What is a typhoon eye

Structure of typhoon: Typhoon is a kind of strong tropical cyclone which is approximately circular. A mature typhoon can be divided into typhoon eye area, strong wind area and rainstorm area near the center, strong wind area and precipitation area outside. On the satellite image, there is a black typhoon eye, a deep convective cloud area near the center, and a spiral cloud and rain belt around it. According to the aircraft detection data, the typhoon has a funnel-shaped typhoon eye area from the inside out, extending downward from the sky to the sea level, with wide cloud walls on both sides of the center and convective cloud columns with different intensities on the periphery. In the temperature field structure and typhoon circulation structure, there is a warm core in the central area. In the structure of pressure field, the height of typhoon circulation can generally reach 12 km, which is a high-altitude counterclockwise vortex in the northern hemisphere, which is called anticyclone in meteorology and clockwise in the southern hemisphere. Sometimes, its circulation height can reach 16 km.

1. Typhoon eye: The typhoon eye is an important symbol of maturity and an area surrounded by the typhoon eye arm. On the satellite cloud image and radar echo image, we can see a black area similar to eyes, which is mostly round or oval with a few concentric circles, and some typhoons are oval, polygonal and horseshoe-shaped.

The diameter of typhoon eye is generally 5 ~ 50km, and the maximum diameter exceeds 100km. In the typhoon eye, there is neither strong wind nor heavy rain, and there are only thin clouds in the sky. You can see the sun during the day and the stars at night. When the typhoon eye passes by, the place will suddenly become calm, and the rainstorm will suddenly stop, which may only take about 30~70 minutes. At this time, it is often mistaken for the typhoon has passed. In many places, major disasters caused by typhoons often occur behind the typhoon eye area.

2. Typhoon Eye Arm: There is an annular cloud belt with strong convection around the typhoon eye, which is called typhoon eye arm or typhoon cloud wall. This is the most important part of the typhoon structure. The strongest wind of 12 and the wild wave of 10 meter high formed by typhoon mainly appear in the eye arm area. At the same time, the eye arm of typhoon is also one of the main areas that cause typhoon rainstorm. There will be tornadoes, lightning, thunderstorms and sometimes hail in the eye arm area. Because typhoons often form strong winds, heavy rains and rough waves, causing great damage, the damage caused by tornadoes, lightning and thunderstorms is often ignored. When investigating the losses caused by typhoons, it was found that some heavy objects can be lifted to more than ten meters or even higher, which may be caused by tornadoes; It is difficult to hear thunder because of the wind and rain in the eye of the typhoon, but lightning is often observed. According to common sense, strong lightning is bound to be accompanied by thunder.

3. Spiral cloud rain belt: The typhoon spiral cloud rain belt is close to the eye arm of the typhoon, with a wide range and various forms. It is a very important feature of typhoon structure, an important sign to judge whether the intensity of tropical cyclones can develop and strengthen, and can also be used to judge the distribution and arrangement characteristics of cloud and rain belts around typhoons. In a typhoon, there are often many symmetrical or asymmetrical spiral clouds with a certain interval of rain bands in the middle. The distribution and intensity of spiral cloud and rain belt are ever-changing. In many rain belts, not only the intensity of each belt is different, but also the intensity of the same rain belt is different. The places affected by spiral cloud and rain belt are often accompanied by showers and gusts. The rainfall intensity and time vary with the development range and intensity of cloud belt, and have similar characteristics in radar echo.

4. Typhoon wind field: Because the pressure in the center of the typhoon is very low, the gradient is very large, and it increases with the approach to the center, so the typhoon wind field is basically strengthened with the increase of the pressure gradient. Near the center, the eye arm of a typhoon is usually the largest. In the typhoon eye area, the wind power decreases rapidly, and some even approach the static wind. Within the radius of 600 kilometers affected by typhoon circulation, the distribution of wind field can be roughly divided into three circles: the outer circle, where the wind power gradually increases inward from 5-6 to 6-8 and 8-9; the middle circle, where the wind power is 10- 12; and the inner circle, which is the eye area of the typhoon, where the wind power is 4-5 or 3.