Tornadoes are small and medium-sized strong cyclones that extend from strong cumulonimbus clouds to the ground. When tornadoes appear, there are often one or several funnel-shaped cloud columns like "noses" extending downward from the bottom of the clouds, accompanied by storms, lightning or hail. When a tornado passes through the water, it can absorb water and rise, forming a water column, which is connected with clouds, commonly known as "dragon with water". After passing through this land, houses are often overturned, telephone poles are blown off, and people, livestock and sundries are even sucked into the air and taken to other places.

1. Characteristics of tornadoes

Tornadoes often occur in thunderstorm weather in summer, especially in the afternoon to evening. The attack range is small, and the diameter of tornadoes is generally between ten meters and several hundred meters. The survival time of tornadoes is generally only a few minutes, and the longest is no more than a few hours. The wind is particularly strong, and the wind speed near the center can reach 100-200m/s, which is extremely destructive. Where tornadoes pass, trees are often pulled up, vehicles are overturned, buildings are destroyed, and sometimes people are sucked away, which is very harmful.

2. Preventive measures for tornadoes

(1) At home, be sure to stay away from doors, windows and external walls of houses and hide in the wall or small room opposite the tornado. The safest place to avoid a tornado is the basement or semi-basement.

(2) In case of emergency such as pole collapse and house collapse, the power supply should be cut off in time to prevent electric shock or fire.

(3) When there is a tornado outside the venue, you should look for low-lying land nearby, but stay away from trees and telephone poles to avoid being smashed, crushed and electrocuted.

(4) When the car encounters a tornado when going out, you must not drive to avoid it, nor do you avoid it in the car, because the car has almost no defense ability against tornadoes. You should leave the car immediately and avoid it in a low-lying place.

1On May 27th, 999, four counties in central Texas, including Austin, the capital, were hit by a huge tornado, killing at least 32 people and injuring dozens. It is reported that in jarrell, 40 miles north of Austin, more than 50 houses collapsed and more than 30 people were killed in the tornado. The damaged area is 1 mile long and 200 yards wide. This is another tornado area in the United States after Miami was hit by a tornado on May 3, 65438.

Generally speaking, a tornado is a whirlwind. When it touches the ground, its diameter ranges from several meters to 1 km, with an average of several hundred meters. Tornadoes range from a few meters to dozens of kilometers, and things are robbed everywhere. The funnel-shaped center of tornado is composed of inhaled dust and condensed water vapor, which is a visible "dragon mouth". On the ocean, especially in the tropics, similar scenes are called sea tornadoes.

Most tornadoes rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere, with some exceptions. The exact mechanism of tornado formation is still under study, and it is generally believed to be related to the violent activities of the atmosphere.

Since19th century, the accuracy of weather forecast has been greatly improved, and various disasters and storms such as tornadoes and hurricanes can be detected by weather radar.