How is lightning formed?

Lightning is an electric spark produced by the breakdown of air by a huge voltage. The turbulent airflow violently heats the adjacent air, making its instantaneous temperature as high as 15000-20000℃, thus making the adjacent air expand rapidly, and the adjacent air pressure can be instantly increased to above 100 atmospheric pressure. Then, it cools rapidly, the air shrinks rapidly and the pressure drops. This sudden expansion and contraction occurred in a short time of a few thousandths of a second, and produced a powerful shock wave that spread in all directions. 0. 1-0.3 seconds after lightning, the air shock wave evolved into sound waves, which is the thunder we heard. Moreover, as the sound waves continue to spread outward, the energy is more and more attenuated and the thunder is more and more dull.

Thunder is a natural phenomenon. When clouds with different charges approach each other in the sky, large-scale discharge will occur. In the scientific definition, lightning refers to the sound wave degenerated from the shock wave generated by the rapid expansion of lightning channel, which is manifested as the rumble accompanied by lightning phenomenon.

Hazards 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 of 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 cause local overheating of the transformer and lead to 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.

Precautions for lightning protection:

1. 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. You shouldn't hide under a big tree or near a telephone pole, or walk or stand in an open field. You should hide in a low-lying place as soon as possible, or try to find a room floor or a dry cave to hide.

2. Don't use an umbrella with a metal handle in thunderstorm weather. 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.

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

4. When it is thunderous and stormy, tourists should immediately turn off the indoor TV, tape recorder, stereo, air conditioner and other electrical appliances to avoid conduction. 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.

5. 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.

6. In a thunderstorm, even if a lightning rod is installed, unplug the indoor TV, refrigerator and antenna power supply quickly to prevent unnecessary losses caused by electromagnetic interference in space. 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.

7. Outside, consider the lightning activity area and see the distance of lightning activity. Generally, you 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.

8. In case of thunderstorm, it is best to 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.