Life cycle and structure of typhoon?

Typhoon is caused by high ground temperature and rising airflow. Because of the high ratio of wind to water vapor on the sea surface, the ground air is replenished along the ground, and the low sea surface temperature absorbs the rising air and water vapor to replenish the space. The following is about how typhoons are formed. I hope you like it!

Causes of typhoon formation

Typhoon originated in tropical ocean, where the temperature is high and a large amount of seawater is evaporated into the air, forming a low pressure center. With the change of air pressure and the movement of the earth itself, the inflow of air also rotates, forming a counterclockwise air vortex, which is a tropical cyclone. As long as the temperature does not drop, this tropical cyclone will get stronger and stronger, and finally a typhoon will form.

The source of typhoon

Typhoon source refers to the sea areas where typhoons often occur, and global typhoons mainly occur in 8 sea areas. In the northern hemisphere, there are five sea areas: western and eastern North Pacific, western North Atlantic, Bay of Bengal and * * *, while in the southern hemisphere, there are three sea areas: western South Pacific, western and eastern South Indian Ocean. From the regional distribution map of the number of typhoons and their percentage in the total number of typhoons in the world, it can be seen that there are 62 typhoons on average every year in the world, and there are many more typhoons in the western ocean than in the eastern ocean. Among them, * * * accounts for 36% * * in the northwest Pacific, while no typhoon has been found in the South Atlantic and Southeast Pacific. Typhoon sources in the northwest Pacific are divided into three relatively concentrated areas: the ocean east of the Philippines, the ocean near Guam and the central South China Sea. The typhoon formed in the South China Sea has a great influence on the south of China.

Most typhoons occur at 5 ~ 20 latitudes, especially at 10 ~ 20, accounting for 65% of the total. However, only 65,438+03% typhoons occur at higher latitudes outside 20, and there are few typhoons within 5 near the equator, but there are occasional typhoons. For example, Fujian Meteorological Observatory found that there were three typhoons in the northwest Pacific Ocean south of 5° n in recent two years. According to the analysis of satellite data in recent ten years, the disturbed clouds that developed into typhoons can be found a few days ago, so the initial position of the disturbance is actually eastward than the previously found position. For example, in the North Atlantic, it used to be thought that most of the initial disturbances that developed into typhoons originated in the middle of the ocean, while some people thought that two-thirds of typhoon disturbances originated from the African continent every year according to cloud image analysis. These disturbances usually appear in the form of inverted V-shaped or vortex clouds. They moved westward along the easterly airflow and developed into typhoons when they reached the central North Atlantic and the Caribbean. The initial disturbance position of typhoons in the northwest Pacific and South China Sea is also eastward than that previously found.

Structure of typhoon

Typhoon is a powerful destructive cyclone vortex. It is a mature typhoon, and its bottom layer is divided into three areas according to the speed of convergent airflow: ① outer ring, also called windy area. From the edge of typhoon to the outer edge of vortex area, the radius is about 200 ~ 300 km, and its main feature is that the wind speed to the center increases sharply, and the wind power can reach more than 6 levels; ② The middle circle, also called vortex area. From the edge of the windy area to the eye wall of the typhoon, the radius is about 100km, which is the area with the strongest convection, wind and rain and the most destructive force in the typhoon. ③ Inner ring, also called eye area of typhoon. The radius is about 5 ~ 30km. Most of them are round, and the wind speed decreases rapidly or the wind is calm.

The horizontal distribution of various meteorological elements and weather phenomena in typhoons can be divided into three areas: the outer area * * includes the inner and outer cloud areas * * *, the cloud wall area and the typhoon eye area; The vertical direction can be divided into three levels: low-altitude inflow layer * * * below 1km * *, high-altitude outflow layer * * * above 10km * *, and middle-level updraft layer * * * about 1km * * Figure 65438. In the lower layer around the typhoon, several spiral air currents with isobars in the typhoon area are involved in the typhoon area and converge to rise, which promotes the development of the convective cloud system and forms the outer and inner cloud areas of the typhoon. There are several spiral rain belts in the corresponding cloud system. The more spiral airflow involved in a typhoon, the faster the tangential wind speed becomes. At a certain distance from the typhoon center, the airflow no longer hovers, so a lot of wet air is forced to rise strongly, forming a towering cloud wall around the center. The top of the cumulonimbus cloud wall can be as high as 19 km, which is the cloud wall area.

In typhoon, the maximum wind speed occurs inside the cloud wall, and the maximum rainstorm occurs in the cloud wall area, so the cloud wall area is the storm area most prone to disasters. When the updraft in the cloud wall reaches high altitude, due to the weakening of the pressure gradient, a large amount of air is forcibly thrown out, forming an outer layer, while a small amount of air flows inward into the typhoon center and sinks, resulting in a clear typhoon center, namely the typhoon eye area. The radius of typhoon eye is about 10 ~ 70km, with an average of about 25km. The release and warming of latent heat in the cloud wall area and the sinking and warming of the typhoon eye area make the typhoon a warm-hearted low-pressure system.

At the lower level, typhoons mainly flow into low-pressure inflow. Because of the angular momentum balance, the inner region can produce strong wind speed, and the outflow airflow of anticyclone is in the upper layer. Strong upward movement connects the upper and lower circulation, which is the main feature of typhoon circulation. The hottest temperature in a typhoon is caused by the sinking movement, which occurs at the inner edge of the eye wall, where there is the strongest sinking movement. The convergence is strongest at the maximum wind speed radius in the lower layer of typhoon, and the maximum wind speed radius does not change much with height, and it is in the eye wall.

Life cycle of typhoon

Incubation stage

After a day of sun exposure, strong cumulonimbus clouds will form on the sea surface. The hot air in these cumulonimbus clouds rises, and the surrounding cold air is constantly replenished, and then rises when it is hot. In this way, the air above is hot and the air below is cold. The evaporation of water vapor in the hot air above expands the range of cloud belt, and the expansion of cloud belt makes this movement more intense. Affected by the geostrophic bias, the expanding cloud rotates counterclockwise and clockwise in the southern hemisphere, forming a tropical cyclone. The centrifugal force generated by the rotating air in the tropical cyclone throws the air outward, and the air in the center becomes thinner and thinner, and the pressure becomes smaller and smaller, forming the initial stage of tropical depression-typhoon.

Development * * * enhancement * * stage

Because the air pressure in the tropical depression center is lower than that outside, the surrounding air rushes into the tropical depression and rises when it encounters heat, which provides more energy to the tropical depression, exceeding the output energy. At this time, the air in the tropical depression rotates more violently, the maximum wind force in the center increases, and the central air pressure further decreases. When the maximum wind force near the center reaches a certain standard, it will rise to a higher level, tropical depression will rise to tropical storm, then strong tropical storm and typhoon, and sometimes it will rise to strong typhoon or even super typhoon, depending on the ratio of energy input and output. If the input energy is greater than the output energy, the typhoon will strengthen, and vice versa.

Mature stage

After a long road of development, typhoons have become powerful and capable of causing disasters. If we land at this time, it will cause great losses.

Extinction stage

A typhoon has two dead ends. The first one is that after the typhoon lands on land, it will weaken and die quickly due to the joint influence of ground friction and insufficient energy supply, and the residual cloud system after its death can bring heavy rainfall to a certain place for a long time. The second is that the typhoon turns in the northern part of the East China Sea, lands in South Korea or crosses the Korean Strait, then degenerates into an extratropical cyclone in the Sea of Japan, and then slowly dies out.