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1. How much do you know about thunder and lightning? 1. How is thunder and lightning formed? answer: Lightning is a discharge phenomenon in the atmosphere, which occurs in cumulonimbus clouds. During the formation of cumulonimbus clouds, some clouds are positively charged and some are negatively charged. Their electrostatic induction to the earth causes heterogeneous charges to be generated on the ground or on the surface of buildings (structures). When the charges accumulate to a certain extent, the electric field intensity between clouds of different charges or between clouds and the earth can penetrate the air (generally 25-30kv/cm) and start free discharge, which we call "pioneer discharge". The cloud-to-ground leader discharge develops gradually from the cloud to the ground. When it reaches the ground (buildings on the ground, overhead transmission lines, etc.), a reverse main discharge from the ground to the cloud will occur. In the main discharge stage, due to the violent neutralization of opposite charges, a large lightning current (generally tens to hundreds of kiloamps) will appear, followed by strong lightning and loud noises, forming lightning. 2. What are the harmful forms of lightning? answer: Lightning strikes are extremely destructive, and their destructive effects are comprehensive, including damage to electrical, thermal and mechanical properties. According to the different characteristics of lightning generation and hazards, lightning can be divided into the following four types:: 1. Direct lightning strikes are caused by discharges between clouds and protrusions on the ground. Direct-hit lightning can injure and kill humans and animals in an instant. Huge lightning current flows into the ground, causing extremely high voltage to ground at the lightning strike point and the connected metal parts, which may directly lead to electric shock accidents due to contact voltage or step voltage. 2. Spherical thunder Spherical thunder is a spherical fireball that emits red light or extremely bright white light. Spherical mines can invade indoors through doors, windows, chimneys and other channels, which is extremely dangerous. 3. Lightning induction Lightning induction is divided into two types: electrostatic induction and electromagnetic induction. Electrostatic induction is caused by thunderclouds approaching the ground, which induces a large amount of opposite charges on the top of protrusions on the ground. After the thundercloud and other parts are discharged, the charge on the top of the protrusion loses its restraint and propagates extremely quickly along the protrusion in the form of lightning waves. Electromagnetic induction is caused by the huge lightning current producing a rapidly changing strong magnetic field in the surrounding space after a lightning strike. This magnetic field can induce a very high voltage on nearby metal conductors, causing secondary discharge to the human body and damaging electrical equipment. 4. Lightning intrusion wave Lightning shock wave is a lightning wave that rapidly propagates along the line or pipeline due to the impact voltage generated on overhead lines or aerial metal pipelines due to lightning strikes. Lightning intrusion waves can destroy the insulation of electrical equipment, causing high voltage to flow into low voltage, causing serious electric shock accidents. 3. How to protect the human body after being struck by lightning? answer: When the human body is struck by lightning, people often think that the person who was struck by lightning still has electricity, and they dare not rescue and delay the rescue time. In fact, this concept is wrong. If you are in a state of "suspended death" due to fainting due to lightning strikes, you can take the following rescue methods:: 1. Perform mouth-to-mouth artificial respiration. The earlier artificial respiration is performed after a lightning strike, the better the recovery of the injured person's body, because the human brain's lack of oxygen for more than ten minutes will be fatal. If cardiopulmonary resuscitation can be performed within 4 minutes and the heart can resume beating, there may still be time to save the patient. 2. Perform cardiac massage on the injured person and quickly notify the hospital for rescue treatment. If you encounter a group of people who are struck by lightning, it doesn't matter those who groan. You should first rescue those who can no longer make a sound. 3. If the injured person's clothes catch fire after being struck by lightning, you should immediately let the injured person lie down so that the flames will not burn the face, and pour water on the injured person, or wrap the injured person with a thick coat, blanket, etc. to isolate the air to extinguish the flames. 4. Where should you hide during thunder? answer: general principles: First, the position of the human body should be kept as low as possible to reduce the risk of direct lightning strikes. ； Second, the contact parts of the human body and the ground, such as the feet, should be as close as possible, and the smaller the contact with the ground, the better, in order to reduce the "step voltage". 1. During thunder and lightning, if you feel your skin tingling or your hair standing on end, it is a sign that thunder and lightning is coming and you should avoid it immediately. 2. If you are in trees, buildings or other tall objects, you should leave immediately. If it is too late to leave the tall object, you should find some dry insulation and place it underground, sit on it, and adopt a squatting lightning protection posture, keeping your feet together. Never place your hands together on the ground. Never lie down. Although the height is reduced at this time, the risk of "step voltage" increases. Water conducts electricity, so wet objects are not insulating. 3. Do not take shelter from thunderstorms at the entrance of caves, under large rocks or overhanging rocks, because these places will become spark gaps, and arcs will be generated when current passes through them, which can injure people. But deep caves are very safe, so you should try to go inside. 4. Stay away from iron bars and other metal objects. It's not just a direct electric shock that's fatal. After lightning strikes a conductor, electrical energy is released instantly, and arcs are emitted to both sides for several meters. In addition, the hot electric light causes the surrounding air to expand rapidly, creating a shock wave. The sound produced by these shock waves is thunder. If heard at close range, the powerful sound waves may damage the lungs, and in severe cases can kill people. 5. If you are in an open place during a thunderstorm, you should squat on the ground immediately. This can reduce the risk of being struck by lightning. Do not support the ground with your hands, as this will expand the contact range between your body and the ground and increase the risk of being struck by lightning. Hold your knees with your hands, keep your chest close to your knees, and lower your head as much as possible, because the head is the most vulnerable to lightning strikes. 6. Lone trees and isolated huts in open areas and on mountain tops should be avoided because they are vulnerable to lightning strikes. It is very dangerous to take shelter from the rain at this time, especially when standing under low branches that stretch far to both sides. However, things are divided into two. If there is a dense forest in the wild and no other lightning protection place can be found for a while, you can also use the dense forest to protect yourself from lightning, because the chances of being struck by lightning are similar everywhere in the dense forest. At this time, as long as you do not stand at the edge of the forest, it is best to choose a clearing in the forest, put your feet together, and keep a similar distance from the surrounding trees. 7. In principle, during thunder and lightning, you should try to avoid tall objects that are not equipped with lightning protection equipment, such as tall towers, large cranes, haystacks and tents in open areas, and do not go to commanding heights such as mountain tops or ridges. Do not approach any part of the lightning protection equipment. Railways, long stretches of metal railings, and other bulky metal objects should also be avoided. 8. If you are swimming in a river, river, lake or swimming pool and encounter a thunderstorm, you should go ashore and leave as soon as possible. Because the water surface is susceptible to lightning strikes, and if you are injured by lightning strikes in the water, it also increases the risk of drowning. In addition, try not to stay on ships without lightning protection equipment, especially wooden sailboats with high masts. 9. If you are driving, you should stay in the car. The car shell is made of metal. Due to 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, or drive tractors during thunder and lightning. 10. If you are at home, unplug the outdoor antenna plug and power plug of the TV. Do not get close to windows, and stay as far away from lights, wires, telephone lines and other incoming wires as possible. 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 indoors, they should be several meters apart. If you are outdoors, wearing rubber-soled shoes or boots can provide protection, but it is not completely safe. 11. According to the ancient saying, when there is thunder and lightning, you should close the windows and doors and leave the fireplace. In fact, this does not have much effect. Keeping windows and doors closed is only suitable for dealing with ball lightning, but this type of lightning is extremely rare and there is still a lack of reliable information on it. Ordinary lightning will not enter a house through an open window. 5. Will installing a lightning rod make it “foolproof”? answer: Many people think that everything will be fine after installing a lightning rod on a building, but this is not the case. Lightning rods can only reduce the risk of a building being struck by direct lightning, but it cannot protect the electronic and electrical equipment inside the building. Why is this? Powerful lightning will produce changes in electrostatic fields, changes in magnetic fields and electromagnetic radiation. Especially when lightning enters the lightning rod system on a building and discharges lightning current underground, a powerful electromagnetic field will be generated, which is commonly known as induction lightning. Due to electromagnetic induction, induced current can be generated in nearby closed metal loops, and induced electromotive force can also be generated in nearby non-closed metal objects. Its rapid change time is extremely short, and the induced voltage is very high, even generating sparks. The withstand voltage of electronic and electrical equipment, especially microelectronic equipment, is very low. The electromagnetic field generated by lightning will cause damage to many electronic and electrical equipment within a certain range, and even cause fires. At the same time, lightning also interferes with the normal operation of radio communications and various electronic equipment. Therefore, lightning protection experts propose that electronic equipment must be protected against lightning in all aspects and comprehensively. Not only must we protect against direct lightning, but we must also protect against induction lightning. 6. Why are lightning disaster losses becoming more and more serious in rural areas? answer: In recent years, losses from lightning strikes in rural areas have been increasing year by year. The reason is that with the increase in farmers' income, many rural families have used household appliances such as televisions and telephones. However, they do not know that these household appliances are the main culprits of "drawing lightning into the house." This is mainly because: First, most of the houses in rural areas are built by farmers themselves. Since there is no corresponding lightning protection knowledge during construction, their houses do not have any lightning protection devices at all. Secondly, in order to increase the reception effect of TV programs, TV receiving antennas in rural areas are generally erected more than 10 meters above the roof, and bamboo poles are often used as supports. Once a thunderstorm occurs, the lightning is easy to catch with the metal receiving antenna, and then introduced into the room by the antenna feeder, causing damage to the TV and other indoor facilities or casualties. Third, most of the power lines and telephone lines in rural areas are supported by relatively empty overhead poles. After thunderstorms strike in open farmland, these overhead power lines and telephone lines will be introduced indoors, causing damage to indoor equipment and casualties. 2. How to protect against lightning 1. How to protect against lightning in rural areas? answer: Because people live in scattered rural areas, the cost of taking lightning protection measures will be higher. First of all, your house's water tower and TV receiving antenna (self-mounted antenna), as well as tall trees close to the house and pedestrian walkways, are all recipients of direct lightning strikes. This requires the installation of lightning rods or belts to prevent direct lightning strikes according to the site conditions. Otherwise, it will directly cause personal casualties and damage to family property during lightning strikes. At present, rural households generally have power lines (generally without protective ground wires), telephone lines, shared TV signal receiving lines (generally not optical cables), rural cable broadcast lines and self-installed TV receiving antennas, etc., which will direct lightning waves into the room. For the safety of you and your property, it is recommended that you install lightning protection devices in time. If limited by economic conditions, it can be completed in stages. When you have no time to install lightning protection equipment, you can take the following temporary measures:: 1. When planting tall trees, be sure to keep a certain distance from houses and pedestrian passages. 2. When going out, pull down the main power switch at home (the general switch can be regarded as a path when struck by lightning because the gap is too small), unplug the TV receiving antenna, and remove the telephone incoming plug. 3. When someone is at home, complete the process in item 2 above before confirming that a thunderstorm is coming. (If a thunderstorm has already arrived, you must not close the gate or dial the line.) People should try to keep their distance from them. 4. Children feel a sense of excitement during thunderstorms, so they must not be allowed to run outside the house. 5. When you are facing a thunderstorm in the wild, you should not get close to high (low) voltage lines, electric poles, flagpoles, or iron towers, nor should you take shelter under big trees. Instead, you should go to low-lying areas as early as possible. If you are in an open area, you should squat on the spot. Thunderstorms come and go quickly, persistence means safety. 2. How to protect schools from lightning? answer: Schools should conscientiously implement regular testing of lightning protection devices, review of lightning protection project design, and completion acceptance management. The site selection and planning of each new school must be reviewed by the local meteorological authority and a lightning strike risk assessment can be conducted before construction. ； The user of each lightning protection device must apply to the local lightning protection technical service agency before the thunderstorm season and accept the safety inspection of the lightning protection device. The lightning protection devices of various school buildings (structures), computer information systems, network classrooms and other facilities must be tested once a year. The lightning protection engineering design of each school must be submitted to the local meteorological authority for review. Only after passing the review can it be delivered for construction. After the project is completed, the lightning protection device completion acceptance permit document issued by the local meteorological authority must be obtained before it can be put into use. Lightning protection technical service agencies at all levels should promptly organize testing of lightning protection devices declared for testing by schools and issue testing reports. ； If the test fails, the user must make timely corrections according to relevant requirements. For schools in remote mountainous areas that are temporarily unable to implement lightning protection project rectification, it is necessary to strengthen the education and publicity of lightning protection safety knowledge for teachers and students, and education on emergency rescue measures for lightning strikes. At the same time, the flagpoles, antennas and other metal facilities protruding from the roof of classrooms with incomplete lightning protection facilities and metal protective railings should be removed. When thunderstorms come, school teachers should immediately organize students to stay away from windows and walls to minimize the risk of lightning disasters. 3. How to protect household appliances from lightning during thunderstorm season? answer: The main thing that affects the safety of household appliances is electromagnetic pulse caused by lightning strikes. There are four main ways of intrusion:: Electricity lines, telephone lines, cable or wireless television feeders, exterior walls or pillars of houses. Among them, the first three ways are all directly connected to external circuits of household appliances. When these circuits are overhead and enter the room, the harm is more serious. So, how can we ensure the safety of household appliances and the people who use them? First, close doors and windows and stay at least 1 meter away from wires, lamp holders, sockets, and TVs. Do not pull the wire for drying clothes to the window or door to keep the room dry. Do not make phone calls, watch TV or listen to stereos, and unplug all household appliances. It is best to install lightning arresters on power lines and telephone lines at home. 4. How do we identify whether a house has effective lightning protection function? answer: When people look at a building, they often pay attention to whether the building's orientation, lighting, ventilation, etc. are satisfactory, but ignore whether the building is safe and has the function of protecting against lightning attacks. In 2004, there were 19 building fires and explosions caused by lightning strikes in our province, resulting in 156 deaths and injuries. Here, lightning protection experts remind you that the lightning protection safety of buildings cannot be ignored, and lightning protection safety cannot be careless. Regarding the lightning protection function of a building, self-examination and judgment can be made through the following aspects:: First, there must be a lightning protection facility certificate issued by a professional department (lightning protection center). If there is no lightning protection facility inspection certificate, that is, the building's lightning protection device has not been inspected and accepted by a professional lightning protection department, there is no safety guarantee. The second is to check whether there are safe lightning protection facilities on the roof of your residential building, that is, lightning rods or lightning protection strips. ； Check whether the distribution box has lightning protection grounding terminals, whether the power sockets in the residence have safety grounding wires, and whether large metal doors, windows and other metal structures on the exterior walls of high-rise residences have safety grounding measures. If you are unsure whether your home is safe, you can consult a lightning protection expert. With the continuous improvement of people's living standards, at present, power distribution rooms (boxes) of new generation residential buildings should be installed with power surge arresters, which can play a very good role in protecting the household appliances of residential residents. If you want to buy a beautiful and safe building, you must check whether it has a lightning protection facility certificate when purchasing a new home, and be careful not to be deceived. 5. How to judge your own safety during thunder? answer: According to statistics, most of the casualties suffered from lightning strikes are people who take shelter under big trees and are active in open environments. How do you know if you are safe when there is lightning and thunder? Lightning is actually an electrical discharge phenomenon. The reason why thunder and lightning occur is that a strong electric field is formed at the bottom of the cloud and between the cloud and the ground. When it reaches or exceeds 300-500 kilovolts per meter, a discharge phenomenon occurs, which is lightning. What usually causes harm to people is cloud and ground flashes. The process of lightning is very fast. The lightning that people see is only a brief flash, but at this moment, several or dozens of discharge processes have already occurred, which can be described as "fast as lightning." The easiest way to determine whether you are in a distant thunderstorm or a near thunderstorm is: When you hear thunder and see lightning, you can determine the distance between your location and lightning. Because lightning and thunder occur at the same time, but the propagation speed of light is fast, 300,000 kilometers per second, while the propagation speed of thunder is only 340 meters per second, which is much slower than the speed of light. If you hear thunder within 1 second after seeing lightning, that is, in the blink of an eye, it means that the location of the lightning strike is 300 meters away. ； If the time interval between seeing lightning and hearing thunder is 5 seconds, it means that the lightning strike occurred about 1.6 kilometers away. If you are in an open area at the time, you should immediately put your feet together, squat down, or take shelter in a nearby building. However, you should not enter low pavilions, straw sheds and other places without lightning protection facilities. Usually people who are struck by lightning cannot hear the sound of thunder. According to survivors of lightning strikes, there is only a "hissing" sound like tearing cloth in their ears. 3. The magical effects of thunder and lightning 1. The wonderful "doctor" of thunder and lightning Research has found that "thunderstorm therapy" is effective. After every thunderstorm, the gas molecules in the air dissociate into negatively charged negative oxygen ions under the action of lightning. Researchers have also calculated that after a thunderstorm, the number of negative oxygen ions per cubic centimeter of air can reach more than 10,000 (while in downtown areas on a sunny day, the number of negative oxygen ions is only a few dozen). Practice has shown that negative oxygen ions, known as "vitamins of the air", are very beneficial to human health. Therefore, medical scientists simulated the magical effect of thunderstorms and introduced negative oxygen ions into the ward. The results showed that when the ratio of negative oxygen ions to positive ions in indoor air is controlled at 9: 1, it can promote the treatment of asthma, burns, ulcers and other trauma. ； It can reduce indoor bacteria and prevent neonatal infections. ； At the same time, it also has a positive therapeutic effect on allergic rhinitis, atrophic gastritis, neurodermatitis, joint pain and other diseases. 4. The contribution of thunder and lightning to human progress When people understand thunder and lightning, the first thing they think of is that it will cause serious losses to people's lives and property. Therefore, people have had a deep fear of lightning phenomena since ancient times. However, you may not know that thunder and lightning also play an important role in human progress. First of all, thunder and lightning played an important role in the origin of life. In the prehistoric period, there were a large amount of gases erupted by volcanoes - methane, ammonia, hydrogen and water vapor - around the earth. Under the action of ultraviolet light, space radiation and strong lightning strikes, these gases produced the "basic components" of living organisms - amino acids, so that primitive life with the ability to self-replicate and reproduce was finally slowly produced. Second, thunder and lightning brought fire to humans. During the evolution from apes to humans, forest fires caused by lightning strikes inspired our ancestors to learn to use fire. The bodies of animals burned to death in forest fires tasted more delicious than animals eaten alive, which made ancient humans * I'm used to eating cooked food. Long-term consumption of nutritious fire food promotes the development of human muscles and brain, making human beings take a big step forward in their evolutionary journey. Third, lightning can purify the environment. When lightning occurs, strong electrochemical and photochemical effects will cause a chemical reaction of part of the oxygen in the air to generate ozone, which has a bactericidal effect. Therefore, after a thunder and lightning, a small amount of ozone is filled in the air. In addition, during thunderstorms, the air is "cleaned" again, making people feel extra fresh and comfortable. Fourth, the invisible contribution of thunder and lightning in agriculture is even greater. Lightning causes oxygen and nitrogen in the air to vaporize into nitrogen dioxide. Nitrogen dioxide is dissolved by rainwater and falls to the ground, becoming a necessary natural nitrogen fertilizer for farmland. Some people estimate that approximately 400 million tons of nitrogen fertilizer are generated due to lightning every year. The lush growth of crops in areas where thunder and lightning often occur is proof of the fertilizer produced by lightning. Scientists have also discovered that lightning can also cause voltage between high altitude and the ground. The greater the voltage, the stronger the plant's photosynthesis and respiration capabilities. Someone has observed and compared that within 1-2 days after lightning, the growth and metabolism of plants are particularly vigorous. If there are 5-6 lightning strikes during the growth period of crops, the maturity period of the crops will be advanced by about a week. Also, there are 8 million lightning strikes every day on the earth. In a lightning strike, the voltage between the cloud and the earth can reach 100 million volts, the current intensity can reach 100,000 amperes, the length of lightning can reach 10,000 meters, the diameter of the spark can be more than ten centimeters, and the power of lightning can reach 10 billion kilowatts, which is thousands of times the power generated by my country's Gezhouba Hydropower Station. At present, people have not figured out how to use lightning to benefit mankind, but lightning is indeed a powerful energy source.