The weather in Alabama

There are five tornadoes every day in the United States. What about every year? 1000 to 2000 tornadoes. Tornadoes in the United States are not only numerous, but also strong. America is called "the land of tornadoes". So what is the reason? This is mainly related to the geographical location, climatic conditions and atmospheric circulation characteristics of the United States. ?

The United States faces the Atlantic Ocean in the east, the Pacific Ocean in the west and the Gulf of Mexico in the south. A large number of water vapor continuously flows from the east, west and south to the United States. With more water vapor, thunderstorm clouds are easy to develop. When the thunderstorm cloud develops to a certain intensity, it will produce a tornado.

The United States is mainly located in the middle latitude. Spring and summer are often controlled by subtropical high, and even autumn and winter are often affected by its edge. The western edge of the subtropical high is the place where the airflow convergence rises most strongly, and the eastern and southeastern airflow is the most active place in the southern and western parts of the subtropical high. It continuously transports a large amount of warm and humid air from the Atlantic Ocean and the Gulf of Mexico to the United States, which is a sufficient condition for the formation of thunderstorm clouds. Thunderstorm clouds continue to develop strongly, and tornadoes follow.

The most tornadoes in the United States are in the midwest, and about 54% occur in spring. ? In May, the subtropical high controlled the United States, and its western edge just stayed in the midwest. At this time, the southeast airflow transported a lot of warm and humid air from south to north in the Gulf of Mexico. With sufficient water vapor in the air and strong vertical upward movement, thunderstorm clouds will develop strongly, often developing into a tornado, resulting in tornadoes. ? In June, a lot of warm and humid air moved northward to Kansas, Nebraska and Iowa. Moved to Canada in July, since then, the number of tornadoes in the United States has been greatly reduced. According to the statistics of the past 50 years, the number of tornadoes over the United States has increased by at least 35 times. Sometimes there is no tornado, but there will be a tornado. This special tornado is called "Yunlong-free tornado", which accounts for about half of tornadoes in the United States. This is indeed a strange phenomenon. How did it come into being?

Scientists believe that this is closely related to the increase in the number of Mercedes-Benz cars on the road. At present, there are no fewer than 2 million cars and more than 600,000 trucks on major highways in the United States. Traffic in America is on the right. Whenever two high-speed cars pass through the bus, an air vortex in the counterclockwise direction will be formed. The air vortex generated by millions of cars will be superimposed to form a powerful vortex. Once this powerful vortex encounters favorable weather system and high temperature and humidity conditions, it will also induce tornadoes.