What are the dangers of lightning and how to avoid lightning strikes?

1. The generation of thunder and lightning

Thunder and lightning generally occur in cumulonimbus clouds with strong convection, so they are often accompanied by strong gusts of wind and heavy rain, and sometimes hail and tornadoes. . The tops of cumulonimbus clouds are generally higher, reaching up to 20 kilometers, and there are often ice crystals in the upper parts of the clouds. Processes such as the attachment of ice crystals, the breakup of water droplets, and air convection generate charges in clouds. The distribution of charges in clouds is more complex, 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 develops 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.

2. Hazards of lightning

The hazards of lightning are generally divided into two categories: one is the thermal effect and electrodynamic effect of direct lightning strikes on buildings; the other is the secondary effects of lightning. The secondary effect is the electrostatic induction and electromagnetic induction generated by lightning current. The specific hazards of lightning are as follows:

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

2． The hyperthermic effect of lightning current will release a powerful current of tens to thousands of amperes and generate a large amount of heat energy. The heat at the lightning strike point will be very high, which can cause metal to melt and cause fires and explosions.

3． The main manifestations of lightning electromechanical effects include explosion, distortion, collapse, tearing and other phenomena of objects struck by lightning, resulting in property losses and casualties.

4. The electrostatic induction of lightning current can cause the conductor of the struck object to induce a large amount of charges that are opposite to the properties of lightning. When the lightning disappears and has no time to dissipate, a very high voltage will be generated and a discharge will occur, leading to a fire.

5． The electromagnetic induction of lightning current will generate a strong alternating electromagnetic field around the lightning strike point. The induced current can cause local overheating of the transformer and lead to fire.

6． The intrusion of lightning waves and the counterattack of the high voltage on the lightning protection device to the building can also cause the distribution device or electrical circuit to break, causing burning and fire.

3. Methods to prevent lightning

1. Install lightning protection devices on buildings. That is, the lightning protection device is used to introduce the lightning current into the earth and disappear.

2. During thunderstorms, people should not get close to high-voltage transformer rooms, high-voltage wires, isolated high-rise buildings, chimneys, poles, large trees, flagpoles, etc., and do not stand on open highlands or in large areas. Take shelter from the rain under a tree.

3. Umbrellas with metal posts cannot be used. When operating in the suburbs or in the open air, do not use metal tools, such as crowbars, etc.

4. Do not wear wet clothes near or stand on the stacks of open-air metal products.

5. Do not turn on your mobile phone on the top of a mountain during a thunderstorm, let alone make any phone calls.

6. Do not touch or approach the grounding conductor of the lightning protection device during thunderstorms.

7. During thunderstorms, lighting lines, telephone lines, TV lines and other lines should be kept away indoors to prevent people from being injured by lightning.

8. During thunder and rain, it is strictly forbidden to stay on the top of a mountain or on a high hill, and you must not continue to climb up to watch the rain. You cannot hide under big trees or near telephone poles, and do not walk or walk. If you are standing in an open field, you should hide in a low-lying area as soon as possible, or find shelter on the floor of a house or a dry cave as much as possible.

9. During thunderstorms, do not use metal-handled umbrellas. Take off metal-framed glasses, watches, and trouser belts. If you are traveling by bicycle, leave the bicycle as soon as possible and stay away from other metal objects to avoid conductive electricity. And was struck by lightning.

10. During thunderstorms, do not go swimming, boating, fishing, etc. in rivers, lakes, etc.

11. During lightning, thunder, wind and rain, if tourists are resting in the hotel, they should immediately turn off the TV, radio, stereo, air conditioner and other electrical appliances in the room to avoid electrical conduction. When thunder strikes, it is safer to be in the center of the room. Do not stay directly under the lamp, or lean on pillars, walls, or doors and windows to avoid accidents caused by induced electricity during thunder.

When a lightning strike occurs, traveling companions should take the patient to the hospital immediately. If breathing and heartbeat have stopped at that time, mouth-to-mouth artificial respiration and external chest heart massage should be performed immediately on the spot, and on-site rescue should be actively carried out. Don't rush to the hospital without resuscitation, otherwise it will delay the pathogenesis and lead to death. Sometimes, artificial respiration and extrathoracic cardiac massage should be continued on the way to the hospital. In addition, pay attention to keeping the patient warm. If there are mental symptoms such as mania, convulsions and convulsions, a cold compress should be applied to the head. For electric burns, under first aid conditions, only need to be kept dry or bandaged.

When a thunderstorm occurs, even if a lightning rod is installed, the indoor TV, refrigerator and antenna power supply should be unplugged quickly to prevent unnecessary losses caused by space electromagnetic wave interference. In addition, judging from the formation and occurrence process of lightning and thunder, open fields, on top of buildings, under tall trees, near rivers, lakes, ponds, and humid areas are areas prone to lightning strikes.

Wang Hongmin, a member of the National Technical Committee for Standardization of Electrical Installations in Buildings: When outdoors, consider the lightning activity area and see how far the lightning activity is. Generally, you can tell the distance by listening to the thunder. Don’t hide behind lightning rods and large lights. Under the tree.

Do not hold an umbrella in an open place, because umbrellas have needle points and the electric field intensity is more concentrated. Don't use your cell phone in open areas. Squat down and put your feet together.

Experts finally emphasized that in the event of a thunderstorm, it is best for citizens to take shelter in a building with metal doors and windows or lightning rods. A car with a metal body is also the best "lightning shelter." Once these buildings or cars are struck by lightning, their metal structures or lightning protection devices or the metal itself will conduct lightning current into the ground.