If two lightning branches seem to reach the ground at the same time, they are called forked lightning.
Fork lightning is like a linear lightning with upside down branches.When the lightning develops from cloud to ground, the cascade leader lightning often goes along the fork road between the irregular distribution of positive space difficulties, thus forming a bowl shaped trunk and developing many branched forked lightning around.
Storm clouds can usually generate electric charges. The bottom layer is negative, and the top layer is positive. In addition, positive charges are induced on the ground, making it move with the clouds like a shadow.Positive and negative charges attract each other, but air is not a good conductor.The positive charges on the ground rush to the top of trees, hills, tall buildings and even the human body, trying to meet the clouds with negative charges;On the other hand, the negatively charged dendritic tentacles on the cloud extend downward, and the more downward they extend, the closer they are to the ground.Finally, the positive and negative charges finally overcome the air barrier and connect.The huge current flows straight from the ground to the clouds along a conducting duct, producing a bright and eye-catching "flash" - this islightning。
When the lightning develops from cloud to ground, the cascade leader lightning often goes along the fork road between the irregular distribution of positive space difficulties, thus forming a bowl shaped trunk and developing many branched forked lightning around.
characteristic
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It is a kind of linear lightning that appears in the form of rather obvious bending and branching branches.
Linear lightning is generally a kind of giant electrical spark with winding branches, 2-3 km long, and 10 km long. It is the strongest lightning and poses the greatest threat to power, telecommunications systems, people, animals and buildings.When the electric field strength between the thundercloud and the earth or between the thunderclouds increases to the strength enough to damage the air insulation (up to 100kV/m) due to the gradual accumulation of free charges, a strong discharge phenomenon will occur. At the moment of discharge, there is great energy. The electric pressure can be accumulated to more than 1000-100000kV, and the discharge current can be up to hundreds of thousands of amperes,The discharge time is only a few thousandths of a second.Linear lightning is mostly the discharge between thunderclouds and the earth, but there are also some discharges between thunderclouds.This kind of lightning can strike at different places at the same time, generally divided into leading discharge and main discharge stages.In most cases (more than 50-70%), the discharge process between the thundercloud and the earth is not single but multiple, that is, it is composed of several single discharges successively developing on the same channel.The number of repeated discharges is generally 1-27, the duration of a single discharge is generally 0.001~0.02 seconds, and the interval between discharges is 0.01~0.05 seconds.
difference
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Fork lightning, super lightning and black lightning
Super lightningCompared with forked lightning, its power is more than 100 times greater.Research shows that forked lightning can generate 1 billion watts of power, while super lightning can generate at least 100 billion watts of power, and some even reach 100 billion watts.The old residents of Newfoundland's Bell Island still remember the scene of a super lightning attack in 1978, which is unforgettable: at that time, many people's doors and windows erupted blue flames, and the houses located about kilometers away were shocked, making a "cluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclucluclu.Fortunately, such lightning is rare.
Black lightningIt is produced by molecular aerosol aggregates, which come from the long-term effects of the sun, cosmic light, cloud electric field, strip lightning and other physical and chemical factors in the atmosphere.They are hot and charged materials, which are easy to explode or turn into spherical lightning.The observation results show that the occurrence of black lightning in the near ground layer is rare.If any, they mostly fall near trees, masts, houses and metals.Black lightning is often ignored because it looks like a lump or mud ball, like dirt.It is small in size and difficult for radar to find, but it carries a lot of energy, especially for metal, which is called "hidden mine in the air".If the flying plane touches the black lightning, the consequences are unimaginable.When it is close to the ground, people may mistake it for a bird or something else. If it is hit with something, it will explode immediately when it is touched.Black lightning is a kind of lightning with greater danger and harm, and general lightning protection facilities such as lightning rod, lightning ball, lightning protection network, etc. do not work on it.[1]
utilize
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For many years, because of the harm of lightning to people, animals and buildings, people always try their best to avoid contact with lightning.In fact, lightning has a great impact on agricultural production and human daily life!With the development of science, today, the problem of using lightning to serve mankind has been paid attention to and studied.Maybe, in a few years' time, we will also try to use some special equipment to guide the lightning in the sky to the ground as much as possible, just like the lightning rod is widely used.At the moment when lightning flashes, its power is about 100 times larger than that of the largest nuclear hydropower plant in the United States in the world.If this electric energy is used for lifting, it will be enough to lift 60000 or 70000 kilograms of goods one or two meters high.Thunderstorm can promote the growth of crops has just been introduced.In addition, because lightning produces ozone in the sky, and this gas has the function of absorbing a large amount of ultraviolet rays, people will not be affected by excessive ultraviolet radiation in the sun.[2]
explore
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Many people want to expose the secret of thunder and lightning.The first person to do experiments and succeed was American Franklin.In July 1725, Franklin made an experiment that shocked the world.Before the thunderstorm was coming, he put a big kite into the sky. The kite flew higher and higher, and it was almost invisible to the naked eye. At this time, the heavy rain poured down, and Franklin's hand holding the kite line suddenly felt numb. Then, the copper bell hanging at the bottom of the kite line touched, and sparks came out with the sound."Success! Success!" Franklin threw down his kite and shouted excitedly.At the risk of his life, he finally solved the mystery of thunder and lightning.
In 1753, in order to verify Franklin's experiment, Lehmann, a famous Russian electrician, was killed by lightning, which was the first victim of the lightning experiment.The price of blood has made many people wary and afraid of lightning tests.But Franklin did not flinch. After many tests, he made a practical lightning rod.He fixed a few meters long iron pole on the roof with insulating materials, and tied a thick wire on the pole until it reached the ground.When lightning strikes the house, it will go straight to the earth through the wire along the metal pole, and the house building is intact.Lightning rods have spread to Britain, Germany, France, and finally all over the world.[3]
Hazard prevention
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Lightning has the characteristics of short discharge time, large impulse current, high impulse voltage, large heat release, and has great destructive power.So far, although it is impossible for human beings to control lightning, people have accumulated a lot of knowledge and experience about lightning protection through long-term exploration and practice.
Lightning protection of buildings
In thunderstorm season, lightning electromagnetic field induction or lightning wave will affect the safety of buildings and household appliances,Lightning wave invasionThe main ways are: wire, telephone line, cable TV or wireless TV feeder, etc.Therefore, lightning protection measures mainly start from the following aspects: ① Buildings should be installed according to lightning protection design specificationsLightning protection device, such as lightning rod, downlead, etc.; ②The power line, telephone line and TV signal line introduced into the house shall be shielded and grounded. For example, when the feeder of outdoor antenna is close to the lightning rod or down lead, the feeder shall be threaded through a metal tube.
Personal lightning protection
1. Indoor lightning protection
When there is strong thunder and lightning, do not stand on the roof or the roof. It is better to stay at home, close the doors and windows of the house, and do not venture out;It is better to unplug all the household appliances at home, do not use the radio with an external antenna, do not watch TV, do not turn on the air conditioner, do not use computers, and do not make phone calls.It should be noted that solar water heaters should not be used for bathing in thunderstorm weather, because solar water heaters are generally installed at high places on the roof, which are vulnerable to lightning attacks. Once lightning strikes, a large amount of high-voltage current will enter the bathroom along the metal pipe and hot water. If someone is bathing at this time, it may cause the water heater to burn,Serious accidents such as explosion, fire or casualties may occur.Try to keep away from metal doors and windows and metal curtain walls;Do not approach or touch any metal pipeline, including water pipe, heating pipe, gas pipe, etc.
2. Outdoor lightning protection
When encountering thunderstorm weather outdoors, do not carry metal farm tools such as iron chisels, hoes, pickaxes, etc. on your shoulders, and do not use umbrellas with metal tips, because metal is the conductor of current, which can easily lead to lightning;Do not answer or call mobile phones outdoors, because the electromagnetic waves emitted by mobile phones can easily lead to lightning.Try to find a place to avoid lightning strike as soon as possible, but do not drive a motorcycle, ride a bicycle or run in the rain, because the greater the step of the body, the greater the voltage, and the easier it is to hurt people.It is necessary to remind farmers that when looking for shelter from rain, they should never go to isolated low buildings, such as melon sheds, pavilions, water pump houses, etc., because they are all protruding objects in the wilderness and easy to attract lightning;In addition, generally tall objects and the tip of objects are also vulnerable to lightning strikes, so it is not allowed to approach tall objects such as iron towers, chimneys, power poles, etc. outdoors, let alone shelter from rain under big trees.Generally speaking, buildings equipped with lightning rods, steel frames or steel plate concrete can be used as lightning protection sites;In addition, the car with a complete metal carriage is also an ideal place to avoid lightning strikes, and its lightning arrester or metal frame will lead lightning current underground.If you are in a mountainous area, you can also take shelter from the rain under the rocks or in caves.If no suitable lightning protection place can be found in a short period of time, the center of gravity should be lowered as far as possible to reduce the contact area between the human body and the ground. At this time, try to squat down and take off the metal objects on the body, such as glasses, watches, keys, necklaces, etc. with metal frames, and put them several meters away, feet together, hands on knees, and body forward, but never lie on the ground or in a pit.If you can put on a raincoat, the lightning protection effect will be better.The crowd in the wild, whether moving or stationary, should be several meters away from each other. Do not crowd together or hold hands together to prevent electric current from conducting each other.In thunderstorm weather, do not go near the river, river, lake, pond and other water surfaces. The water edge is more vulnerable to lightning strikes because of the high conductivity of water. The water land junction is the intersection of soil resistance and water resistance, which forms an interface with large changes in resistivity, and lightning tends to these places.If someone is struck by lightning, burned or shocked, he or she must not be electrified before rescue.[4]
News report
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According to the Daily Mail on October 31, when the storm hit at around 6:00 p.m. on October 30, Gregory, an artist from Queens, New York, USA?Gregory Skolozdra climbed onto the roof of his studio on Long Island and caught an incredible lightning that broke the sky after the purple clouds.
It is reported that the weather during the day was unusually warm, but in the afternoon, dark clouds suddenly shrouded the sky, accompanied by lightning and thunder, and soon it began to hail.
From the video shot by Skorozadra, it can be seen that behind the purple cloud, a lightning burst into the night sky, and his camera was shaken.The lightning lightened the dark sky.Then the lightning disappeared quickly.Soon I heard the deafening thunder.
In the thunderstorm, someCar alarmAre triggered.The citizens all posted the huge hail 0.75 inch (about 1.9 cm) that hit the city on social media and played an apocalyptic joke.[5]
