Actually, thunderbolts are giant electrical sparks. This is evident when lightning rushes from the ground to the clouds or from the clouds to the ground, although it can also be transmitted in or between clouds. The airflow that makes up the storm clouds can separate strong electrical energy within the clouds.
The positive current gathers in the lower part of the cloud layer, and the negative current gathers in the upper part of the cloud layer or on the ground, just like electromagnetism, the positive and negative electricity attract each other. After continuous transmission, the positive and negative currents collide to form huge electric sparks, thus forming lightning.
Because the speed of light is about a million times faster than the speed of sound, there is a certain time lag between lightning and the accompanying thunder. The distance between you and the storm can be calculated by counting the number of seconds between the lightning and thunder, and dividing by 5 meters. The number is the distance between you and the storm in miles, that is:
You and The distance of the storm (miles) = the time difference between lightning and thunder (seconds) / 5 (meters).
Thunder is caused by the thermal expansion and explosion of air caused by the impact of millions of volts of lightning current. The sound of thunder itself is not harmful. The possibility of being struck by lightning during a thunderstorm is very small, but the phenomenon of lightning strikes cannot be completely accurately predicted, so precautions should be taken to reduce the danger.
Lightning always zigzags along the path of least resistance. Its path in the air depends entirely on the electric field and charge distribution in the air, and it is usually only affected by ground conditions when it is ten meters to a hundred meters above the ground. Generally speaking, the ground has good electrical conductivity, and there are tall and prominent objects, which are all vulnerable to lightning strikes. For example, the geological conditions of metal minerals with good electrical conductivity are more likely to be struck by lightning than the general geological conditions. The chances of lightning strikes in wet soil are more than those in dry soil, sandy land and rocky ground. It is easier to be struck by lightning than the flat land, and the mountains are more susceptible to lightning strikes than the valleys.
There is no doubt that direct lightning strikes can cause injury, but sometimes, even if not directly struck by lightning, accidents can occur due to the proximity of lightning strikes. This is because when the strong lightning current is discharged to the ground, due to the existence of ground resistance, the voltage value near the lightning strike point is much larger than that far from the lightning strike point. Therefore, if a person stands with two feet apart, one foot is close to the lightning strike point and the other foot is far away from the lightning strike point, a certain potential difference will be generated, which is often referred to as “stepping voltage”. Part of the lightning current flows through the human body due to the “stepping voltage”, which can also cause damage. The worse the conductivity of the ground surface, the greater the “step voltage”.
Safety measures in thunderstorms
General principles: First, the position of the human body should be kept as low as possible to reduce the risk of direct lightning strikes; The contact parts such as the feet should be as close as possible, and the smaller the contact with the ground, the better to reduce the “stepping voltage”.
· When lightning strikes, if you feel skin tingling or your hair stands up, it is a sign that lightning is coming, and you should avoid it immediately.
· If you are in a tall object such as a tree or a building, you should leave immediately. If it is too late to leave the tall object, you should find some dry insulation and put it on the ground, sit on it, adopt a squatting lightning protection position, and pay attention to keeping your feet together. Do not put your hands together on the ground. Never lie down, although the height is reduced at this time, it increases the risk of “stepping voltage”. Water conducts electricity, so wet objects are not insulating.
·Do not avoid thunderstorms at the entrance of caves, under big rocks or under overhanging rocks, because these places will become spark gaps, and arcs can be hurt when electric current passes through them. But the deep cave is very safe, you should try to go inside.
·Stay away from iron bars and other metal objects. Not a direct electric shock is enough to kill. After the lightning strikes the conductor, the electric energy is released in an instant, and the arcs are shot to both sides for several meters. In addition, the hot electric light causes the surrounding air to expand rapidly, creating shock waves. The sound of these shock waves is the sound of thunder. If heard at close range, the powerful sound waves can shock the lungs and, in severe cases, can kill a person.
·If you are in an open place during a thunderstorm, you should squat on the ground immediately to reduce the risk of being struck by lightning. Do not support the ground with your hands, as this will expand the range of contact between your body and the ground and increase the risk of being struck by lightning. Tuck your knees with your hands, keep your chest close to your knees, and lower your head as much as possible, because your head is the most vulnerable to lightning strikes.
· Open areas and lone trees and solitary huts on hilltops should be avoided as they are vulnerable to lightning strikes. It is very dangerous to take shelter in it at this time, especially under low branches that stretch far to the sides. However, things are divided into two parts. If there is a dense forest in the wild and no other lightning shelter can be found for a while, then the dense forest can also be used to avoid lightning, because the chances of being struck by lightning are almost the same everywhere in the dense forest. At this time, as long as you don’t stand on the edge of the forest, it is best to choose a clearing in the forest, with your feet together, and keep a similar distance from the surrounding trees.
· In principle, during the lightning period, you should try to avoid tall objects without lightning protection equipment, such as tall towers, cranes, haystacks and tents
in open areas, and do not go to the commanding heights such as the top of the mountain or the mountain beam. go. Do not approach any part of the lightning protection device. Railroads, long metal railings and other bulky metal objects should also be avoided.
·If you are swimming in a river, river, lake or swimming pool and you experience a thunderstorm, get ashore and leave immediately. Because the surface of the water is vulnerable to lightning strikes, and if you are injured by lightning strikes in the water, it also increases the risk of drowning. Also, try not to stay on boats without lightning protection equipment, especially tall wooden sailboats.
· If you are driving, stay in your vehicle. The car shell is made of metal, and because of its shielding effect, even if lightning strikes the car, it will not hurt anyone. Therefore, the car is an ideal place to avoid lightning strikes. However, it is best not to ride horses, bicycles, motorcycles and open tractors during thunderstorms.
· If at home, unplug the TV’s outdoor antenna plug and power plug. Do not go close to the window, keep as far away as possible from the incoming wires such as electric lights, electric wires, telephone lines, etc. In buildings without lightning protection devices, avoid steel columns, water pipes and heating pipes to prevent lightning current from entering the human body through them. In addition, if there are many people in the room, it should be a few meters apart from each other. When outdoors, wearing rubber-soled shoes or boots is protective, but not completely safe.
· According to the old saying, you should close your windows and doors and leave the fireplace during thunderstorms, but it doesn’t really help. Closing windows and doors is only suitable for dealing with ball lightning, but such lightning electrodes are rare and there is still a lack of reliable information about them. Ordinary lightning does not shoot into the house through an open window.
Rescue after a lightning strike
A lightning strike is not necessarily fatal. Many have survived with only electric shocks and minor burns. Lightning strikes can also lead to broken bones (due to muscle spasms caused by electric shock), severe burns, and other trauma.
Lightning injury is a frequent occurrence, if you do not avoid or take improper lightning protection measures, you will suffer a great threat. According to reports, in Switzerland, about 10 people per million people are struck by lightning every year; in the United States, more people are killed by lightning accidents each year than in hurricanes; in Japan, there was a lightning strike in 1968. 11 accident of a child. Therefore, it is necessary for us to understand the specific measures of lightning protection and rescue methods after being struck by lightning.
Lightning injury is mainly due to the effect of strong lightning current. Its main danger to the human body. Often not burns. If lightning strikes the head and travels through the body to the ground, it can paralyze a person’s nerves and heart, and can be fatal. After a person is struck by lightning current, the heart either stops beating, or the beating rate is extremely irregular and vibrates. Both of these conditions stop blood circulation, cause damage to the nerves in the brain, and can kill a person within minutes. After being struck by lightning, it is still possible to revive in time. Sometimes even not feeling the victim’s breath and pulse does not necessarily mean “death”. If rescued in time (such as artificial respiration), it can often restore the heartbeat and breathing of the “dead”. In addition, lightning strikes can set the casualty’s clothing on fire, as well as melt the casualty’s metal accessories and watch straps.
·If the casualty’s clothing catches fire, lie down immediately so that the flames do not burn to the face. Otherwise, the injured may die from hypoxia or burns. You can also splash water on the injured person, or wrap the injured person in a thick coat or blanket to put out the flames. The injured should not run because of panic, which will make the fire burn more and more vigorously. They can roll on the ground to extinguish the flame, or lie down in a depression or pool with water to extinguish the flame. Cool the wound with cold water, then cover with a dressing, such as a folded handkerchief with the clean side over the wound, and wrap it with a clean cloth.
·If the electrocuted person is unconscious, place him in a recumbent position to keep him warm and comfortable. It is very necessary to immediately implement electric shock first aid and artificial respiration.