How is lightning produced?

The cause of lightning is generally thought to be that various particles in the cloud accumulate charges due to collision and friction. When the amount of charge reaches a certain level, which is equivalent to the voltage between clouds or between clouds and ground reaching or exceeding a certain value, the local electric field strength will reach or exceed the electrical breakdown strength of air at that time, thus causing discharge.

Electricity in the air rapidly heats and expands the air through discharge, and is compressed into plasma due to the expansion, thus generating a special component of lightning (sound of shock wave).

The current of lightning is very large, the peak value can generally reach tens of thousands of amperes, but the duration is very short, generally only a few tens of microseconds. Therefore, the energy of lightning current is not as great as expected. However, the power of lightning current is very large, which does great damage to buildings and other equipment, especially electrical equipment. Therefore, it is necessary to install lightning rods or lightning arresters to protect the safety of these buildings and equipment to some extent.

Extended data

General conditions of lightning activity

(1) Geological conditions: When the relative value of soil resistivity is small, it is beneficial to the rapid accumulation of charges. Places with small local resistivity are vulnerable to lightning; Resistivity mutation and underground conductive mineral deposits are vulnerable to lightning; In fact, the resistivity of grounding grid will increase the probability of lightning strike.

(2) Topographic conditions: the direction of the valley is consistent with the wind direction, and the tuyere or downwind valley is easily struck by lightning; Hillsides near lakes and oceans are more vulnerable to lightning.

(3) Ground conditions: It is beneficial to establish a good discharge channel between thunderstorm clouds and the earth. Isolated buildings in the open space, towering buildings in the complex are vulnerable to lightning; Trees, receiving antennas and transmission lines in mountainous areas are vulnerable to lightning strikes; In line with the characteristics of tip discharge, the probability of lightning stroke will also increase after the base station tower is built.

Lightning can be divided into direct lightning, electromagnetic pulse, spherical lightning and cloud flash. Among them, direct lightning and spherical lightning will do harm to people and buildings, while electromagnetic pulse mainly affects electronic equipment, mainly induction; Cloud flash occurs between two clouds or on both sides of a cloud, so it does the least harm to human beings.

Baidu encyclopedia-thunder and lightning