What are the hazards of lightning?

Lightning is usually produced in cumulonimbus clouds with strong convection, so it is often accompanied by strong gusts and heavy rains, and sometimes accompanied by hail and tornadoes. The top of cumulonimbus clouds is generally very high, up to 20 kilometers, and there are often ice crystals on the top of the clouds. The attachment of ice crystals, the breaking of water droplets and air convection make clouds generate charges. The distribution of charge in the cloud is complicated, but generally speaking, the upper part of the cloud is dominated by positive charges and the lower part is dominated by negative charges. Therefore, a potential difference is formed between the upper and lower parts of the cloud. When the potential difference reaches a certain level, discharge will occur, which is our common lightning phenomenon.

Second, the harm of lightning

The hazards of lightning are generally divided into two categories: first, the direct impact of lightning on buildings has thermal effect and electrodynamics effect; The second is the secondary action of lightning, that is, electrostatic induction and electromagnetic induction caused by lightning current. The specific hazards of lightning are as follows:

1. The high voltage effect of lightning current will produce impulse voltage as high as tens of thousands of volts or even hundreds of thousands of volts. Such a huge voltage will instantly impact electrical equipment, which is enough to break through insulation, short-circuit the equipment and lead to direct disasters such as combustion and explosion.

2. The high heat effect of lightning current will release tens to thousands of amperes of powerful current and generate a lot of heat energy. The heat at the lightning point will be very high, which will lead to metal melting and fire explosion.

3. The mechanical effect of lightning current is mainly manifested in the explosion, distortion, collapse and tear of the struck object, resulting in property losses and casualties.

4. The electrostatic induction of lightning current can induce a large amount of charge on the conductor of the struck object, which is contrary to the nature of lightning. When lightning disappears before it can disperse, high voltage discharge will occur, which will lead to fire.

5. The electromagnetic induction of lightning current will produce a strong alternating electromagnetic field around the lightning strike point, and the induced current can overheat the transformer locally, leading to a fire.

6. The invasion of lightning waves and the high-voltage counterattack of lightning protection devices on buildings will also cause open-circuit combustion of power distribution devices or electrical lines, leading to fires.

Third, the methods to prevent lightning strikes

1. Lightning protection device is installed on the building. That is, lightning protection devices are used to introduce lightning current into the earth and then disappear.

2. During a thunderstorm, people should not go near high-voltage distribution rooms, high-voltage wires and isolated tall buildings, chimneys, poles, trees, flagpoles, etc. Not to mention standing in an empty highland or under a big tree to shelter from the rain.

3. You can't use umbrellas with metal columns. Do not use metal tools, such as crowbars, when working in the suburbs or in the open air.

4. Don't wear wet clothes near or stand on metal objects in the open air.

Don't turn on your mobile phone at the top of the mountain in thunderstorm weather, let alone use it.

6. Don't touch and approach the grounding conductor of lightning protection device in thunderstorm days.

7. In a thunderstorm, leave lighting lines, telephone lines, TV lines and other lines indoors to prevent lightning from infringing on people and being hurt.

8. When it thunders and rains, it is forbidden to stay at the top of the mountain or in hilly areas. More importantly, it is forbidden to continue to push up the rain scene. Don't hide under big trees or near telephone poles, and don't walk or stand in open fields. You should hide in a low-lying place as soon as possible, or try to find a room floor or a dry cave to escape.

9. In thunderstorm weather, don't use an umbrella with a metal handle, and take off glasses, watches and belts with metal frames. If you travel by bike, you should leave the bike as soon as possible and stay away from other metal objects to avoid being struck by lightning.

10. Don't go swimming, boating or fishing in rivers and lakes in thunderstorm weather.

1 1. In case of lightning, thunder and rainstorm, visitors should immediately turn off the indoor TV, tape recorder, stereo, air conditioner and other electrical appliances to avoid using electricity. It's safer in the middle of the room when it thunders. Don't stay under the electric light, and don't lean against posts, walls, doors and windows, so as to avoid accidents caused by induced electricity when it thunders.

When lightning strikes, the traveling companion should take the patient to the hospital immediately. If breathing and heartbeat have stopped at that time, mouth-to-mouth resuscitation and chest massage should be carried out at the scene immediately, and on-site rescue should be actively carried out. Don't rush to the hospital without rescue, otherwise it will delay the onset and lead to death. Sometimes, on the way to the hospital, we have to continue artificial respiration and chest massage. In addition, we should pay attention to keep patients warm. If you have mania, convulsions, convulsions and other mental symptoms, you should also do a cold compress on your head. For the part of electric burn, in the case of first aid, it is only necessary to keep it dry or bandage it.

During a thunderstorm, even if a lightning rod is installed, it is necessary to quickly unplug the indoor TV, refrigerator and antenna power supply to prevent unnecessary losses caused by space electromagnetic interference. In addition, judging from the formation and occurrence process of lightning, lightning accidents mostly occur in open fields, the tops of buildings, tall trees, rivers, lakes, ponds and wet areas.

Wang Hongmin, member of the National Technical Committee for Standardization of Building Electrical Devices: Outside, we should consider the lightning activity area and see the distance of lightning activity. Generally, we can judge the distance by listening to thunder. Don't hide under lightning rods and trees. Don't open an umbrella in an open place, because the umbrella has a needle tip and the electric field intensity should be concentrated. Don't use your mobile phone in an open place. Squat down and put your feet together.

Experts finally stressed that in case of thunderstorm, citizens had better hide in buildings with metal doors and windows or lightning rods. The car with metal body is also the best "lightning protection place". Once these buildings or cars are struck by lightning, their metal frames or lightning protection devices or the metal itself will lead lightning current into the ground.