How did the thunder and lightning come from?

Lightning is a discharge phenomenon in the atmosphere, which is mostly formed in cumulonimbus clouds. Cumulonimbus clouds will move with the change of temperature and airflow. When triboelectricity moves, it will form charged clouds, some of which are positively charged and some are negatively charged. In addition, buildings and trees under clouds often have opposite charges due to electrostatic induction. With the accumulation of charge, the voltage of Lei Yun gradually rises. When the Lei Yun with different charges and the earth bulge are close to each other to a certain extent, the electric field between them will exceed 25 ~ 30 kV/cm, resulting in strong discharge and strong flash. Because the temperature is as high as 2000℃ when discharging, the air expands rapidly when heated, and then there is the roar of explosion, which is lightning and thunder. The size, quantity and activity of lightning are related to the topography, meteorological conditions and latitude of each area. Generally, the number of lightning strikes in mountainous areas is more than that in plains. The higher a building is, the more chances it will be struck by lightning. The types of lightning and its hazards are very destructive, and their destructive effects are comprehensive, including the damage to electrical, thermal and mechanical properties. According to the different characteristics of lightning generation and harm, lightning can be divided into the following four types: 1. Direct lightning is formed by the discharge between clouds and ground protrusions. Direct lightning can instantly hurt and kill people and animals. Huge lightning current flows into the ground, which produces extremely high voltage to the ground at the lightning strike point and its connected metal parts, which may directly lead to electric shock accidents of contact voltage or step voltage. 2. Spherical Thunder Spherical Thunder is a spherical fireball that emits red light or extremely bright white light. Spherical lightning can invade the room from doors, windows and chimneys, which is extremely dangerous. 3. Lightning induction Lightning induction can be divided into electrostatic induction and electromagnetic induction. Electrostatic induction is due to the fact that Lei Yun is close to the ground, and a large number of opposite charges are induced at the top of the ground protrusion. After the discharge in Lei Yun and other parts, the charge at the top of the bump loses its bondage and propagates along the bump very quickly in the form of lightning wave. Electromagnetic induction is caused by the rapid change of strong magnetic field in the surrounding space caused by huge lightning current after lightning strike. This magnetic field can induce high voltage on nearby metal conductors, causing secondary discharge to human body, thus damaging electrical equipment. 4. Lightning invasion wave Lightning shock wave is a lightning wave that is generated on overhead lines or overhead metal pipelines due to lightning strikes and spreads rapidly along the pipelines. Lightning intrusion wave will destroy the insulation of electrical equipment, make high voltage jump into low voltage, and cause serious electric shock accidents. Lightning protection measures for buildings 1. The main measures to prevent direct lightning are to install lightning rods, lightning protection nets and lightning protection belts on buildings. Install lightning protection wires above high voltage transmission lines. A complete lightning protection device includes lightning receptor, down conductor and grounding device. The lightning receptor uses its protruding position above the protected object to guide the lightning to itself, and then leaks the lightning current into the earth through the down conductor and grounding device, thus protecting the protected object from lightning strike. The requirements of lightning protection grounding devices are basically the same as those of general grounding devices, and the resistance of grounding devices for preventing direct lightning in buildings in use shall not be greater than10 ~ 30Ω. 2. Anti-lightning induction In order to prevent the high voltage generated by electrostatic induction, the metal equipment, metal pipes and structural steel bars of the building should be grounded. 3. Lightning invasion wave In order to prevent the lightning invasion wave from entering the room along the low-voltage line, it is best to use underground cable for power supply and ground the metal sheath of the cable. How to prevent people from being struck by lightning is an inevitable natural disaster. However, the consequences of taking or not taking measures and whether the measures are scientific are very different. For example, a farmer in a certain place in Guangxi was harvesting peanuts in the field when a thunderstorm suddenly started. Several gay men ran to a nearby cave to shelter from the rain, and seven women set up tents with plastic film to shelter from the rain. They were all struck by lightning, and six of them died instantly. The lightning protection measures are as follows: 1. Indoor lightning protection (1) The outdoor wireless of the TV should be separated from the TV, and the grounding wire should be used in thunderstorm weather. (2) Doors and windows should be closed in thunderstorm weather to prevent spherical lightning from entering the room and causing damage. (3) During a thunderstorm, it is best for the human body to stay away from the lines and equipment that may conduct lightning intrusion waves 1.5m or more, in other words, try not to use electrical appliances for the time being, and it is best to unplug the power supply; Don't call; Stay away from indoor metal equipment such as radiators, water pipes and sewer pipes; Try to stay away from power lines, telephone lines and broadcast lines to prevent the secondary discharge of these lines and equipment to the human body. In addition, don't wear wet clothes and stay away from wet walls. 2. How to avoid lightning strike outdoors (1) In order to prevent counterattack accidents and injuries caused by step voltage, stay away from the lightning rod and its grounding down lead of buildings. (2) Stay away from all kinds of antennas, telephone poles and iron towers. Chimneys and flagpoles, if possible, should enter cars and ships with wide metal frames and lightning protection facilities or metal shells, but canvas wagons, tractors and motorcycles are more dangerous when struck by lightning and should leave as soon as possible. (3) Try to stay away from hills, coasts, rivers and pools; Leave the barbed wire and metal clothesline as soon as possible. Isolated trees and small buildings without lightning protection devices. (4) Try not to walk in the wild in thunderstorm weather. In case of emergency, you can wear waterproof raincoats such as plastic; Walk slowly, with smaller steps; Don't ride livestock or walk by bike; Don't use umbrellas with metal poles, and don't carry tools with metal poles such as shovels and hoes on your shoulders. Before being struck by lightning, people will suddenly feel their hair stand on end or their skin tremble. At this time, they should lie flat on the ground immediately, or choose to squat down in a low-lying place, with their feet together, their arms crossed and their heads down to minimize exposure. How to rescue a person injured by lightning? People who are burned by lightning or severely electrocuted will not be prosecuted. Let him lie down at once, put out the fire on him and save him. If the injured person is unconscious, but still breathing and heartbeat, there is a great possibility of self-healing. The injured person should be allowed to lie on his back comfortably. After a quiet rest, he should be sent to the hospital for treatment. If the injured person has stopped breathing or his heart is beating, he should be given mouth-to-mouth artificial respiration and heart massage quickly, and be careful not to stop the first aid of cardiopulmonary resuscitation on the way to the hospital.