In my impression, typhoons and heavy rains are the "patent" of the southeastern coastal cities, and they are not surprising. However, this year, these northern cities in the northeast that are not coastal have a lot of heavy rains, and even caused floods. Why are there so many typhoons and heavy rains this year in places other than the coastal areas of Northeast China? Next, let’s find out today.
1. First of all, what are typhoons and heavy rains
Typhoons are a type of tropical cyclones. Tropical cyclones are low-pressure vortices that occur on tropical or subtropical oceans. According to the definition of the World Meteorological Organization, a tropical cyclone center with sustained wind speed above level 12 (ie, 32.7 meters to 41.4 meters per second) is called a typhoon or hurricane. Different regions have different names. Generally speaking, tropical cyclones generated in the Pacific are called "typhoons"; while tropical cyclones generated in the Atlantic are called "hurricanes".
Heavy rain (English name torrential rain; rainstorm; storm) refers to rain with high precipitation intensity, often forming in cumulonimbus clouds. China's meteorological regulations stipulate that heavy rainfall with a precipitation of more than 50 mm in 24 hours is called "heavy rain". It is divided into three levels according to its precipitation intensity, that is, a 24-hour precipitation of 50-99.9 mm is called a "heavy rainstorm", a precipitation of 100-249.9 mm is called a "heavy rainstorm", and a precipitation of 250 mm or more is called a "heavy rainstorm." However, due to different precipitation and terrain characteristics in different places, the standards for heavy rain and floods are also different in different places.
2. Why are there so many typhoons and heavy rains this year in areas other than the coastal areas of Northeast China?
A typhoon is a "tropical cyclone" generated on tropical or subtropical oceans with sustained central wind speeds of magnitude 12 to 13 (ie, 32.7 to 41.4 meters per second).
As one of the countries most severely affected by typhoons in the world, China has about 10 typhoons every year, which basically land on the southeastern coast all the way to the west, affecting mainly Fujian, Zhejiang, Guangdong, and Jiangxi. Wait for the southern region. Such path movements originate from the "twitching" of the subtropical high pressure belt.
In July and August, the subtropical high pressure is in a strong period. After extending westward and strengthening, it controls the middle and lower reaches of the Yangtze River in my country. Its main subsidence movement within the control area is not conducive to the development of typhoons. It is like building a barrier for the area north of the Yangtze River, making it difficult for typhoons to "break through" and reach further north.
1. The intensity of typhoons this year is stronger than in previous years
Although so far, only 7 typhoons have been generated in the Pacific Ocean, which is significantly less than in previous years, but there are 6, all of which are Typhoon level, 4 of which are super typhoons. Since the circulation of Typhoon "Dusuri" itself carries a large amount of water vapor, and the subtropical high pressure is on its east side, the pressure gradient between the two will cause the easterly and southeasterly winds in the Beijing-Tianjin-Hebei region to significantly strengthen, pushing the typhoon "up to the western Pacific" over a long distance. The water vapor near "Kanu" is transported to the North China Plain. At the same time, it is blocked by the Taihang Mountains to the west and the Yanshan Mountains to the north. The water vapor is forced to rise, which is conducive to the condensation of water vapor into rain. The combination of the above factors has caused heavy rainfall in the Beijing-Tianjin-Hebei region.
2. Most of this year’s typhoons made landfall in the north.
Whether it was Dusuri in the front or Typhoon Kanu in the future, the main landing areas were in the northern region. After the invasion of Dusuri, water vapor was added by Kanu, and the two typhoons were superimposed, resulting in heavy rain. This is related to this year's subtropical high. This year's subtropical high is distributed in blocks, forming a strong high-pressure dam in the eastern coastal areas of my country, making it difficult for typhoons to land.
3. This year’s typhoon has a large impact area
Because the intensity of this year’s typhoon is relatively large, the impact area is relatively large. For example, the reason why "Dusuri" was able to go all the way north is, on the one hand, its super power when it landed, and on the other hand, because of the special atmospheric situation formed after repeated back and forth with the "subtropical high".
That is to say, this high-pressure dam that used to lie across the middle and lower reaches of the Yangtze River was pushed to North China and the Huanghuai area by the strong residual circulation of "Dusuri". In addition, the mountainous geographical environment in the western part of North China and the " Kanu's continuous water delivery and continuous heavy rains induced flash floods and mudslides, causing river water levels in the region to skyrocket and flooding and waterlogging to occur.
Rain, floods, and disasters are superimposed. Judging from the intensity of the disaster, the direct damage and secondary disasters caused by this round of "typhoon rain" to the northern region are both "unprecedented in a century."
3. What should you do if you encounter a typhoon or rain?
① At home:
1. Properly dispose and clean up flower pots and debris on the windowsill that are easily blown off by strong winds.
2. Close the doors and windows tightly. To prevent the window glass from being shattered by strong winds and injuring people, you can stick a film on the window glass or use tape or paper strips to make a "rice" shape.
3. Check whether the circuit, stove, gas and other facilities are safe, and cut off the power supply and gas.
4. Prepare flashlights, candles and other lighting tools in advance, and stock up on drinking water, food, medicine and related daily necessities to avoid panic buying after water and power outages.
②Outdoors:
If you are outdoors, be more careful when walking and go to a safe building as soon as possible.
1. Stay away from dangerous buildings, telephone poles, billboards, scaffolding, trees, towers and other places that are prone to collapse.
2. When you have to walk outdoors, bend down and walk slowly in an open area so that you can see the road; when you are on a narrow bridge or a high place, crawl forward; stop at corners.
3. Do not forcefully pass through flooded areas, as there may be a risk of falling into a pit. If there are electric wires hanging down near standing water, the person falling into the water may be electrified.
4. Stay away from the water bank. You cannot go to the beach to swim or watch the tide. At this time, it is even more unsafe to sail out to sea.
③While driving:
1. Remember to slow down, keep a distance between vehicles, pay attention to water accumulation on the road, and avoid low-lying roads with water accumulation.
2. When you must wade through water, you should open the skylight in advance and roll down the windows to drive in the waterlogged area. Use low gear, don't stop, don't change gears.
3. The engine cannot be restarted after the vehicle suddenly stalls, and you should get off the vehicle immediately.
4. If you find that the water is below the height of the car door and continues to rise, you must abandon the car decisively.
5. During a typhoon, pay attention to the electronic signs on the road in real time to remind you of the road conditions ahead.
6. If you encounter temporary traffic control, please obey the instructions.
Personal experience: I live in the south and have encountered quite a few typhoons, but they have not reached the point of causing floods. Floods in the north this year are also unexpected, but I can clearly feel the impact of this year’s typhoons. There are indeed more, and they are still connected, but because of the typhoon, I feel that this summer is not very hot, otherwise it would be over 35 degrees at all times, and the bright sun would be unbearable. It feels like there are more and more extreme weather nowadays. Everyone should pay more attention to the prevention of typhoons. In addition, relevant areas should also pay attention to preventing flash floods and geological disasters that may be caused by heavy precipitation.