What is the mystery of the cause of tornado?

Tornado is a funnel-shaped (trunk-shaped) cloud column hanging from the bottom of cumulonimbus cloud and its accompanying very strong cyclone, also known as tornado. The phenomena recorded in the literature, such as silver coin rain, frog rain, soybean rain, iron rain, shrimp rain, bloody bull's head falling from the sky, are all phenomena that tornadoes suck objects on the ground or in water into the sky, take them far away and fall with the rain. Tornadoes are about several meters to hundreds of meters in diameter, and the moving distance is usually several hundred meters to several kilometers, and some can reach dozens of kilometers. The pressure in the center of the tornado is extremely low, and the pressure gradient near the center is extremely high, so the wind speed and rising speed are very high. The wind speed near the tornado center is generally tens to hundreds of meters per second, and in some cases it reaches more than 150 meters per second, and the maximum rising speed is tens to hundreds of meters per second. Because the air pressure in the funnel-shaped cloud column is very low, it has a strong suction effect. When the funnel reaches the land surface, it sucks a lot of dust and other substances into the air, forming a dust column called a tornado. When the funnel reaches the sea surface, it will suck up a very high water column, which is called tornado or tornado. The powerful airflow of a tornado can drag tens of thousands of tons of whole carriages into the air and throw thousands of tons of ships from the sea to the shore. On March 1925, a tornado occurred in the United States, killing 680 people and injuring 1980 people. 1On March 26th, 1967, a tornado occurred in Shanghai, destroying more than 0/0000 houses, pulling up or twisting off 22 high-voltage towers, and its wind resistance was twice that of 12 gale. Tornadoes kill tens of thousands of people on average every year. Although people have long known that tornadoes are formed in a very unstable atmosphere, the physical mechanism of their formation is still unknown. Some scholars put forward a new theory of internal gravity-thermal process, but it can't explain the winter night tornado without strong convection or Thundurus. Tornadoes sometimes sweep everything, and sometimes the things in its center are intact; Sometimes a good horse can be blown several kilometers away, but sometimes only one oak trunk can be blown off; Sometimes the feathers on one side of a chicken are pulled out, but the feathers on the other side are intact, and the reasons for these strange phenomena are even more elusive. In order to subdue and predict tornadoes, people try to explore the law of tornado formation and solve this natural mystery.