China Weather Network News Affected by the ground cyclone, yesterday (July 20) intense and strong convective weather occurred in many places in Jiangsu. Among them, Suqian Shuyang, Lianyungang Guannan and other places were even hit by tornadoes.

As a small-scale weather system, tornadoes are short-lived but extremely destructive.

Do tornadoes happen regularly?

China Weather Network analyzes meteorological big data to reveal when my country's tornadoes are the most common and which areas are more likely to occur.

Tornadoes are the most destructive and can blow up cars and destroy houses

　　Tornadoes, as a kind of highly destructive severe convective weather, are a small-scale air vortex generated under strong unstable weather conditions. between meters.

　　Tornadoes form and disappear quickly, often accompanied by strong convective weather systems such as thunderstorms, hail and heavy rain, and are extremely destructive.

According to the Fujita scale, the tornado strength is divided into 6 levels from EF0 to EF5, with EF0 being the lowest and EF5 being the highest.

　　Tornadoes of EF2 and above are generally referred to as strong tornadoes, and EF2 tornadoes can cause considerable damage, which may cause trees to be uprooted; EF3 tornadoes tend to cause severe damage, and trains may be scraped down; EF4 tornadoes may cause destructive damage, good brick and wood structures and frame structures may be destroyed, and some houses will be shoveled and flattened by Qigan; the damage caused by EF5 tornadoes is devastating. Framed houses can be thrown along with their foundations, reinforced concrete buildings can be severely damaged, and cars can be blown away.

Most of my country has experienced tornadoes, most of which are in Jiangsu and Guangdong.

　　The global tornado mainly occurs in the middle latitudes, North America, Europe, Russia, China, Japan and Australia and other places have tornadoes every year. Among them, the United States is the country with the most tornadoes, with an average of 1141 recorded tornadoes per year (from 2000 to 2020). average), called the "tornado kingdom".

　　my country's tornadoes mainly occur in the eastern plains, and the middle and lower reaches of the Yangtze River are frequent areas.

According to the statistics of the National Climate Center from 1991 to 2020, there are 38 tornadoes per year in my country on average. Jiangsu, Guangdong, Hubei, Anhui and other provinces have more tornadoes, among which Jiangsu and Guangdong have the most, with an average annual tornado of 4.8 and 4.3 respectively. 1, followed by Hubei and Anhui, both with 2.

my country's strong tornadoes occur frequently in spring and summer, with the most frequent occurrence in July

　　Spring and summer are the seasons of frequent tornadoes in my country. From April to August, the number of tornadoes accounts for 92% of the whole year, of which July accounts for the highest proportion, accounting for about 30%.

Judging from the occurrence time of strong tornadoes of EF2 and above, it is also the most in July.

　　According to the statistics of "Spatiotemporal Distribution of Tornadoes in China", from 1961 to 2010, there were 165 strong tornadoes of EF2 level and above in my country, and the occurrence time was mainly concentrated in April to August. , the most in July, accounting for about 28% of the total, followed by April.

　　In addition, the months of tornadoes appear slightly different in different regions.

The most common months in South China are from April to May, in the middle and lower reaches of the Yangtze River from April and July, in North China from June to July, in Northeast China from June to August, and in Southwest China from July to August In July, there were many tornadoes in the northwest region in July.

Strong tornadoes prefer the afternoon around the evening

　　In addition to seasonal differences, there are certain rules in the time of the strong tornadoes appearing in a day, and the tornadoes prefer to "haunt" in the afternoon.

　　According to the statistics of "Spatio-temporal Distribution of Tornadoes in China", from 1961 to 2010, the strong tornadoes that occurred between 12:00 and 20:00 accounted for 70% of the total number of strong tornadoes that can be checked. After the solar radiation during the day, the atmospheric structure is unstable, and the period when strong convective weather is most likely to occur is easy to promote the formation and strengthening of the tornado weather system.

　　In addition to the high incidence period in the afternoon, strong tornadoes often appear in the early morning.

According to statistics, there are 10 strong tornadoes generated from 0:00 to 2:00.

Strong tornadoes occurred less frequently in the morning, with the least occurring from 10:00 to 12:00, only once.

An average of 38 tornadoes occur every year in my country, and the maximum number in 2005 reached 75

　　From the perspective of interannual changes, the periodicity of tornadoes is also more obvious.

According to the statistics of tornadoes recorded from 1991 to 2020, there are an average of 38 tornadoes in my country every year.

Relatively high numbers of tornadoes occurred in the mid-1990s to early 2000s; relatively few tornadoes occurred in the early 1990s and from 2006 to 2020.

Among them, the number of tornadoes was the largest in 2005, reaching 75, and the number of tornadoes in 2020 was the least, only 13.

What to do in the event of a tornado?

　　A tornado is a relatively violent strong convective weather. After a tornado is formed, it generally lasts for ten minutes to several hours. Its attack range is small, but its destructive power is large.

Once encountered, how should we defend against it?

　　First, if you are at home, be sure to stay away from doors, windows, and the outer walls of the house, and hide in the wall or small room opposite to the direction of the tornado. The basement or semi-basement is the safest place to avoid the tornado;

　　Second, in the event of an electric pole falling or a house collapsing, the power supply should be cut off in time to prevent electric shock to the human body or cause a fire;

　　Third, when encountering a tornado in the wild, you should look for low-lying places to lie down on the ground, but keep away from big trees, telephone poles, billboards, fences, etc., so as to avoid being smashed, crushed or electric shock accidents;

　　Fourth, when you go out in a car and encounter a tornado, you should drive in the opposite direction to avoid it, or leave the car immediately and go to a low-lying area to avoid it.

　　Reference article:

　　[1] Da Bing Said Climate · "Tornado Activity and Climate Characteristics in China and the United States"

　　[2] Fan Wenjie, Yu Xiaoding. 2015. "Spatio-temporal distribution characteristics of Chinese tornadoes". Meteorology, 41(7): 793-805.

　　[3] National Climate Center · "Why are there frequent severe convective weather recently?

The authoritative climate cause analysis is here!

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　　[4] Huang Dapeng, Zhao Shanshan, Gao Ge, et al. "Research on the characteristics of tornado disasters in China in the past 30 years" [J]. Rainstorm Disaster, 2016, 35(2): 97-101