How do typhoons form and disappear?

How do typhoons come into being and disappear? Everyone should be familiar with it. Like an earthquake, typhoons are endangering people's homes. Typhoons are natural disasters, not random. So how did typhoons come into being and disappear?

How do typhoons form and disappear? The specific process of Typhoon 1 is as follows:

1, tropical or subtropical ocean surface temperature above 26 degrees Celsius;

2. Due to the high temperature near the ocean surface, a large amount of air expands and rises, which reduces the pressure near the ocean surface, and the peripheral air continuously supplements and flows into the rising area;

3. Affected by the geostrophic force, the inflowing air rotates and the rising air expands and cools;

4. When the water vapor cools and condenses into water droplets, the heat will be released and the low-altitude air will continue to rise;

5. The air pressure near the ocean surface drops lower, and the air rotates more violently, which eventually constitutes a typhoon.

To sum up, a typhoon needs the following conditions: the sea surface water temperature is above 26.5℃; Necessary positive vorticity initial disturbance; The shear of ambient wind in the vertical direction is very small; Low pressure or cloud disturbance is at least several latitudes from the equator.

These four conditions are described in detail as follows:

1, warm ocean surface, seawater temperature higher than 26℃

The temperature and humidity of the upper and lower atmosphere in tropical oceans are mainly determined by the sea surface water temperature. The higher the SST, the higher the temperature and humidity of the lower atmosphere, and the more obvious the potential instability. Typhoons are formed on the warm ocean surface with SST ≥ 26 ~ 27℃. Generally speaking, the global tropical ocean surface meets this condition all year round, and only the tropical southeast Pacific Ocean has an annual SST of ≤ 26℃, which is the main reason why there is no typhoon there.

2. There is a pre-existing interference.

Typhoons are all developed from the pre-existing tropical depression disturbance. According to China's statistics, the tropical cyclones in the western Pacific-South China Sea region come from four initial disturbances in intertropical convergence zone, accounting for 80% ~ 85%; East wind wave, accounting for about10%; The cut-off low pressure in the long wave trough at middle and high latitudes, or the cold vortex at high altitude, accounts for about 5%; Baroclinic disturbance accounts for less than 5%.

3. The location of generation is generally 5 latitudes from the equator.

All typhoons are generated in the tropical ocean at five latitudes from the equator, and only a few typhoons in the northwest Pacific are generated near 3° n, but few typhoons are found within three latitudes near the equator.

4. The vertical shear of the whole troposphere wind should be very small.

The vertical shear of tropospheric wind speed determines whether the latent heat released by convection dispersed in an initial tropical disturbance can be concentrated in a limited space. If the vertical shear is small, the relative motion of the upper and lower air is small, and the latent heat released by condensation always heats the same column in a limited range, so that it quickly heats up to form a warm center structure, and the initial disturbance develops rapidly to form a typhoon. On the other hand, if the upper and lower shear becomes larger, the latent heat will be quickly transported out of the disturbance area, and it will not constitute a warm structure or a typhoon.

Because so far, people have not fully understood the composition of typhoons, and the above list is only the necessary conditions for the composition of typhoons. The initial stage of typhoon is tropical depression, and it usually takes about 2 days from the initial low-pressure circulation to the maximum average wind force near the center, only three or four days for the slow one and only a few hours for the fast one. In the development stage, the typhoon continuously absorbs energy until the central air pressure reaches the lowest value and the wind speed reaches the maximum value. After the typhoon landed, under the joint influence of ground friction and insufficient energy supply, it will quickly weaken the death.

Does the typhoon rotate clockwise or counterclockwise?

The typhoon in the northern hemisphere rotates counterclockwise and the typhoon in the southern hemisphere rotates clockwise.

If the earth does not rotate, then the wind will only blow from the high pressure area to the low pressure area. Because the earth is rotating, when the warm air rises, it will be affected by the "geostrophic deflection force" (strictly speaking, it is also called "Coriolis force").

For example, when you try to draw a straight line on a rotating disk, you actually get a curve. Because the direction of "geostrophic deflection force" is just the opposite in the northern hemisphere, the wind will move counterclockwise around the low pressure area in the northern hemisphere and clockwise around the low pressure area in the southern hemisphere.

In addition to the influence of geostrophic deflection force on the direction of typhoon rotation, people also found a phenomenon: the wear degree of the right rail of trains in northern hemisphere countries is always worse than that of the left rail. The reason is that when the train is running, it will be affected by the geostrophic force to the right, so the pressure on the right rail is greater than that on the left rail.

According to international practice, the maximum wind force near its center is divided into:

Tropical depression, the maximum wind speed is 6 ~ 7, (10.8 ~ 17. 1 ms);

Tropical storm with maximum wind speed of 8-9 (17.2-24.4 milliseconds);

Strong tropical storm with maximum wind speed 10 ~ 1 1, (24.5 ~ 32.6 milliseconds);

Typhoon (ty-typhoon), maximum wind speed 12 ~ 13, (32.7 ~ 41.4 ms);

Strong tropical storm with maximum wind speed14 ~15 (41.5 ~ 50.9 ms);

Super typhoon with maximum wind speed ≥ 16 (≥5 1.0ms).

How did the typhoon finally disappear?

The life span of a typhoon is usually around 3- 10 days, but there are some special ones. For example, Typhoon Rita, which lasted 19 days, will gradually weaken and eventually disappear after entering the land. It is difficult to predict the moving path of typhoon. Many typhoons near Chinese mainland suddenly turn to other places, and they may become stronger after entering the ocean again.

The formation of a typhoon requires a lot of energy and enough water vapor to maintain it. When the typhoon enters the land, the water vapor condition on the land can't maintain the typhoon to continue to develop, and the constant friction between the typhoon and the uneven land consumes a lot of energy, which eventually makes the typhoon disappear. Every year, there are dozens of typhoons in the Pacific Ocean, but usually only a few affect our country.

1956 Typhoon Dai Wen went deep into the mainland. It once entered Anhui, Shanxi, Henan, Hunan and other places, and finally disappeared at the junction of Inner Mongolia and Shaanxi. The typhoon brought us great losses. Many crops were soaked in water and houses were destroyed. Even many people were killed in this typhoon, which caused great losses to the economy.

Therefore, in typhoon weather, you should stay at home honestly, close the doors and windows, and don't run around to prevent some items from falling and hurting yourself. If you live in a low-lying area, you must evacuate to a safe area in advance and pay attention to the weather forecast.

How do typhoons form and disappear? 2 How is the typhoon formed?

In tropical or subtropical oceans where the sea surface temperature exceeds 26℃, due to the high temperature near the ocean surface, a large amount of air expands and rises, which reduces the air pressure near the ocean surface and continuously supplements the inflow and rise of peripheral air.

Affected by the geostrophic force, the inflowing air rotates. The rising air expands and cools, and when the water vapor in it cools and condenses into water droplets, it will release heat and promote the rising of the lower air. In this way, the air pressure near the ocean surface drops lower, and the air rotates more violently, eventually forming a typhoon.

There are two paths for typhoon extinction.

The first one is that after the typhoon lands, 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 long-term heavy rainfall to a certain place. 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.

Typhoon has at least the following benefits for human beings:

First of all, typhoons bring people abundant fresh water. Typhoon brought a lot of rainfall to the coast of China, the coast of the Sea of Japan, India, Southeast Asia and the southeastern United States.

Secondly, the tropical and subtropical areas near the equator have the longest sunshine time, and the dry heat is unbearable. If there is no typhoon to dissipate heat in these areas, it will be hotter there and the surface sand shortage will be more serious. At the same time, the cold zone will be colder and the temperate zone will disappear. China will not have a spring city like Kunming, nor will it have an evergreen Guangzhou, and "Beidacang" and Inner Mongolia grassland will also cease to exist.

Third, the typhoon can reach a top speed of more than 200 kilometers per hour, and it is invincible wherever it goes. This huge energy can directly cause disasters to mankind, but it also keeps the earth in thermal balance and makes mankind live and work in peace and contentment.

Fourth, typhoons can also increase fishing output. Every time a typhoon blows, it turns over the river, rolling up the nutrients in the river bottom and the sea, increasing the bait, attracting fish to gather near the water surface, and naturally increasing the catch.

How do typhoons form and disappear? How did the typhoon disappear?

First of all, we should know that there are two main situations of typhoon death: one is to weaken and disappear; The other is to become an extratropical cyclone.

The typhoon weakened and disappeared.

After the typhoon landed, the water vapor supply decreased, and the energy driving force for the typhoon was gone. At the same time, because the friction on land is much greater than that on the sea, the typhoon structure gradually becomes loose. In addition, the bottom airflow enters the center of the typhoon, and the convergence at the bottom is much greater than the divergence at the top, which destroys the overall structure of the typhoon and will naturally disappear gradually.

Typhoon degenerated into an extratropical cyclone.

When a typhoon moves to a high latitude area, cold air will generally invade, and when it interacts with the typhoon, it is easy to form a cold and warm front, which becomes a temperate frontal cyclone, making the typhoon stop numbering.