What are the hazards 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. It 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.

1995 A tornado occurred in Admore, Oklahoma, USA, and heavy objects such as roofs were blown out dozens of kilometers away. Most of the debris falls on the left side of the tornado passage, and there are often obvious landing areas according to the weight. Lighter debris may fly more than 300 kilometers before landing.

Under the attack of a strong tornado, the roof of the house will fly like a glider. Once the roof is swept away, the rest of the house will collapse. Therefore, if we can strengthen the stability of the roof when building houses, it will help to prevent the tornado from causing huge losses when crossing the border.

The tornado struck suddenly and violently, and the wind force produced was the strongest on the ground. In the United States, the number of deaths caused by tornadoes is second only to lightning every year. Its damage to buildings is also quite serious, often devastating.

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 the town of Jarrell, 40 kilometers north of Austin, more than 50 houses collapsed and more than 30 people were killed in the tornado. The damaged area is 1 km long and 200 yards wide (1 yard ≈ 0.92m). 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 occur and 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.

Tornadoes are usually extremely fast. It is not surprising that the wind speed is 100 m per second, even reaching more than 175 m per second, which is five or six times larger than the typhoon 12. The range of wind is very small, generally the diameter is only 25 ~ 100 meters, and only in rare cases can the diameter reach more than 1 km; It takes only a few minutes from occurrence to disappearance, at most a few hours.

Tornadoes are also very powerful. On September 24th, 1956, a tornado appeared in Shanghai. It easily hoisted a large oil storage barrel weighing 220,000 kg (1 kg = 500g) to an altitude of 15m, and then threw it away from 120m.

1879 at 4 pm on may 30, two dark and thick clouds were merging over northern Kansas. After 15 minutes, a vortex was generated at the lower end of the cloud. The vortex has grown rapidly and become a huge pillar of indomitable spirit. Within three hours, it ran wild all over the state like a dragon, and no one was spared wherever it went. However, the strangest thing happened at the beginning, when the tornado whirled across a small river and met a cliff. Obviously, it is impossible to surpass this obstacle, so the vortex turns to the west, and there happens to be a newly built 75-meter-long railway bridge over there. The tornado vortex actually pulled it down from the stone pier, twisted it a few times, and then threw it into the water.

1626 (6th day of May, Ming Taizu Xi) At 9: 00 am on May 30th, a bizarre disaster suddenly broke out around Beijing Wang Gong factory (now Xuanwu Gate, Beijing). Tianbian Dibao, the official news publication of Ming Dynasty with important historical value, recorded the disaster in detail. Excerpts are as follows: "The east corner of Jizhou collapsed, with hundreds of rotten houses. On the tenth day, two people were dug out of the ground and still alive. Asked, the cloud:' drunk as a dream'. Dig another old man to live. " What force can make three people fly from Beijing to Jizhou 180 miles without dying in the catastrophic disaster of Wang Gong factory? What power can strip people naked and send them hundreds of miles away without hurting people? Why don't naked people know how their clothes are taken off? There must be some inevitable factor at work, but can human beings recognize this inevitable factor in the future? Can this magical power be mastered, controlled and utilized by human beings in the future? These problems are waiting for us to explore.