Typhoon "Niger" will bring heavy rains as it approaches Guangdong. Why do typhoons come so frequently this year?

Because this year the subtropical high is stronger in the west and stronger, which inhibits the formation and northward development of typhoons. Under the influence of the guiding airflow from its south side, typhoons tend to move towards South China. In addition, Guangdong has a long coastline. Therefore, there is a high probability that typhoons will go straight to Guangdong; in addition, cold air activity increases in autumn. When typhoons encounter cold air, it will usually trigger more intense precipitation, so autumn typhoons are more likely to appear "ruthless".

Causes of the formation of typhoons:

Typhoons originate from the tropical sea surface, where the temperature is high and a large amount of sea water is evaporated into the air, forming a low pressure center. With changes in air pressure and the movement of the earth itself, the inflowing air also rotates, forming a counterclockwise rotating air vortex, which is a tropical cyclone. As long as the temperature does not drop, this tropical cyclone will become stronger and stronger, and finally form a typhoon.

Classification of typhoons:

In the past, our country used to call tropical cyclones (Tropical cyclones) formed on tropical oceans above 26°C as typhoons. They were divided into six levels according to their intensity. : Tropical depression, tropical storm, severe tropical storm, typhoon, severe typhoon and super typhoon.

International practice is divided into the following categories based on the maximum wind speed near its center:

Tropical depression (Tropicaldepression), maximum wind speed of level 6~7, (10.8-17.1 m/s);?

Tropical storm (Tropicalstorm), maximum wind speed of level 8 to 9, (17.2 to 24.4m/s);

Severe tropical storm (Severe tropical storm), maximum wind speed of level 10 to 11, (24.5~32.6m/s);

Typhoon (Ty-phoon), maximum wind speed of level 12~13, (32.7m/s~41.4m/s);

Strong Typhoon (severe typhoon), the maximum wind speed is 14~15 levels (41.5m/s~50.9m/s);

Super typhoon (Super Typhoon), the maximum wind speed is ≥16 levels (≥51.0m/s) ).

Benefits of typhoons:

Typhoons have the following benefits to humans:

First, typhoons bring abundant fresh water to people. Typhoons bring large amounts of rain to the coast of China, the Sea of ​​Japan, India, Southeast Asia, and the southeastern United States.

Secondly, tropical and subtropical areas close to the equator receive the longest sunshine hours and are unbearably dry and hot. If there are no typhoons to dissipate the heat in these areas, it will be even hotter and the surface desertification will be more serious. At the same time, the frigid zone will become colder and the temperate zone will disappear. Our country will no longer have a spring city like Kunming, nor will there be Guangzhou, which is evergreen all year round, and the "Beidacang" and Inner Mongolia grasslands will no longer exist.

Thirdly, the maximum speed of a typhoon can reach more than 200 kilometers per hour, causing destruction wherever it goes. This huge energy can directly cause disasters to human beings, but it is also due to this huge energy flow that the earth maintains a thermal balance, allowing human beings to live and work in peace and contentment, and continue to prosper.

Fourth, typhoons can also increase fishing output. Whenever a typhoon hits, the rivers and seas are turned upside down, and the nutrients at the bottom of the rivers and seas are swept up. The bait increases, attracting fish to gather near the water surface, and the catch naturally increases.

Typhoon disaster:

Typhoon is a very destructive and disastrous weather system, but sometimes it can also play a beneficial role in eliminating drought. There are three main aspects of its hazards:

① Strong wind. The maximum wind force near the center of a tropical cyclone reaching typhoon level is level 12 or above.

②Heavy rain. Typhoons are one of the weather systems that bring heavy rains. In the areas where typhoons pass, they may produce 150mm to 300mm of rainfall. A few typhoons can directly or indirectly produce heavy rains of more than 1000mm, such as (indirectly) after the landing of Tropical Cyclone No. 3 in 1975. The extremely heavy rain caused by the inversion channel in southern Henan broke the rainfall record in some areas (Henan 75.8 incident).

③Storm surge. Generally, typhoons can increase the water content of coastal seawater, and the maximum water increase along the coast of Jiangsu Province can reach 3m. Typhoons "9608" and "9711" increased water levels, causing unprecedented high tide levels along the rivers and coasts of Jiangsu Province.

When typhoons pass through, they often bring violent storms and cause huge waves on the sea surface, seriously threatening navigation safety. The increased storm water brought by a typhoon after its landfall may destroy crops, various construction facilities, etc., causing huge losses to people's lives and property.

Typhoon prevention:

Residents

1. Listen, watch or check the typhoon warning information online in time to understand the government's typhoon prevention action countermeasures.

2. Close doors and windows and secure structures that are easily blown by wind.

3. Move from dilapidated houses to a safe place.

4. People in low-lying areas that may be flooded should relocate in time.

5. Check whether circuits, stoves, gas and other facilities are safe.

6. Kindergartens, primary and secondary schools should take temporary evacuation measures and suspend classes when necessary.

7. Open-air group activities or large indoor gatherings should be canceled promptly, and personnel evacuation should be done well.

At sea

1. Before a typhoon approaches, ships should obey orders and immediately seek shelter from the wind.

2. If you cannot escape or encounter a typhoon, you should contact the relevant departments on the shore in time for rescue.

3. When waiting for rescue, emergency measures should be taken proactively, and measures to leave the typhoon should be taken quickly and decisively, such as stopping (delaying), circling (detouring), and crossing (quickly passing through).

4. The calm winds and waves shortly after a strong typhoon may be the calmness when the eye of the typhoon passes by. At this time, ship owners in the port must not go back to reinforce their ships in order to protect their property.

5. If possible, equip the ship with modern equipment such as beacons, radio communication machines, and satellite phones.

6. When there is no radio communication equipment, when a passing ship or aircraft is found, or when it is close to the land, objects can be used to send out an easily detectable distress signal in time, such as stacking the words "SOS". Set off fireworks, send out light and sound signals, shake brightly colored objects, etc.