Doctor biological sciences, Candidate of Physical and Mathematical Sciences K. BOGDANOV.

At every moment in different points The earth sparkles with lightning more than 2000 thunderstorms. Every second, about 50 lightning strikes the earth's surface, and on average each square kilometer of it is struck by lightning six times a year. B. Franklin also showed that lightning striking the earth from thunderclouds is electrical discharges that transfer to it negative charge several tens of pendants, and the amplitude of the current during a lightning strike is from 20 to 100 kA. High-speed photography showed that the lightning discharge lasts a few tenths of a second and consists of several even shorter discharges. Lightning has long been of interest to scientists, but in our time we know only a little more about their nature than 250 years ago, although they were able to detect them even on other planets.

Science and life // Illustrations

The ability to electrify by friction of various materials. The material from the rubbing pair, which is higher in the table, is positively charged, and below it is negatively charged.

The negatively charged bottom of the cloud polarizes the surface of the Earth below it so that it is positively charged, and when the conditions for electrical breakdown appear, a lightning discharge occurs.

Distribution of the frequency of thunderstorms over the surface of land and oceans. The darkest places on the map correspond to frequencies of no more than 0.1 thunderstorms per year per square kilometer, and the brightest - more than 50.

Umbrella with lightning rod. The model was sold in the 19th century and was in demand.

Shooting a liquid or laser at a thundercloud hanging over the stadium diverts the lightning bolt to the side.

Several lightning strikes caused by the launch of a rocket into a thundercloud. The left vertical line is the trace of the rocket.

A large "branchy" fulgurite weighing 7.3 kg, found by the author on the outskirts of Moscow.

Hollow cylindrical fragments of fulgurite formed from melted sand.

White fulgurite from Texas.

Lightning - eternal source recharging electric field Earth. At the beginning of the 20th century, atmospheric probes measured the electric field of the Earth. Its strength at the surface turned out to be about 100 V/m, which corresponds to the total charge of the planet about 400,000 C. Ions serve as charge carriers in the Earth's atmosphere, the concentration of which increases with height and reaches a maximum at an altitude of 50 km, where, under the action of cosmic radiation an electrically conductive layer formed - the ionosphere. Therefore, the electric field of the Earth is the field of a spherical capacitor with an applied voltage of about 400 kV. Under the action of this voltage, a current of 2-4 kA flows from the upper layers to the lower ones, the density of which is 1-2. 10 -12 A/m 2 , and energy up to 1.5 GW is released. And this electric field would disappear if there were no lightning! Therefore, in good weather, the electric capacitor - Earth - is discharged, and during a thunderstorm it is charged.

A person does not feel the electric field of the Earth, since his body is a good conductor. Therefore, the charge of the Earth is also on the surface of the human body, locally distorting the electric field. Under a thundercloud, the density of positive charges induced on the ground can increase significantly, and the electric field strength can exceed 100 kV / m, 1000 times its value in good weather. As a result, the positive charge of each hair on the head of a person standing under a thundercloud increases by the same amount, and they, repelling from each other, stand on end.

Electrification - removal of "charged" dust. To understand how a cloud separates electrical charges, let's remember what electrization is. The easiest way to charge a body is by rubbing it against something else. Electrification by friction is the most old way receiving electrical charges. The very word "electron" in translation from Greek into Russian means amber, since amber has always been negatively charged when rubbed against wool or silk. The magnitude of the charge and its sign depend on the materials of the rubbing bodies.

It is believed that the body, before it was rubbed against another, is electrically neutral. Indeed, if a charged body is left in the air, then oppositely charged dust particles and ions will begin to stick to it. Thus, on the surface of any body there is a layer of "charged" dust, which neutralizes the charge of the body. Therefore, electrification by friction is the process of partial removal of "charged" dust from both bodies. In this case, the result will depend on how much better or worse the "charged" dust is removed from the rubbing bodies.

The cloud is a factory for the production of electric charges. It is hard to imagine that there are a couple of materials listed in the table in the cloud. However, different "charged" dust can appear on the bodies, even if they are made of the same material - it is enough that the surface microstructure differs. For example, when a smooth body rubs against a rough one, both will be electrified.

Thundercloud is great amount steam, part of which condenses into tiny droplets or ice floes. The top of a thundercloud can be at a height of 6-7 km, and the bottom hangs above the ground at a height of 0.5-1 km. Above 3-4 km clouds consist of ice floes different size because the temperature is always below zero. These ice cubes are in constant motion caused by rising currents of warm air from the heated surface of the earth. Small pieces of ice are easier than large ones to be carried away by ascending air currents. Therefore, "nimble" small pieces of ice, moving in upper part clouds, all the time collide with large ones. With each such collision, electrification occurs, in which large pieces of ice are charged negatively, and small ones are positively charged. Over time, positively charged small pieces of ice are at the top of the cloud, and negatively charged large ones at the bottom. In other words, the top of a thunderstorm is positively charged, while the bottom is negatively charged. Everything is ready for a lightning discharge, in which a breakdown of air occurs and a negative charge from the bottom of the thundercloud flows to the Earth.

Lightning - hello from space and source x-ray radiation. However, the cloud itself is not able to electrify itself so as to cause a discharge between its bottom and earth. Electric field strength in thunder cloud never exceeds 400 kV/m, and electrical breakdown in air occurs at a voltage greater than 2500 kV/m. Therefore, for lightning to occur, something else is needed besides an electric field. In 1992, the Russian scientist A. Gurevich from Institute of Physics them. P. N. Lebedev of the Russian Academy of Sciences (FIAN) suggested that cosmic rays, high-energy particles that fall on the Earth from space at near-light speeds, can be a kind of ignition for lightning. Thousands of such particles every second bombard each square meter earth's atmosphere.

According to Gurevich's theory, a particle of cosmic radiation, colliding with an air molecule, ionizes it, resulting in the formation of a huge number of high-energy electrons. Once in the electric field between the cloud and the earth, the electrons are accelerated to near-light speeds, ionizing the path of their movement and, thus, causing an avalanche of electrons moving with them to the earth. The ionized channel created by this avalanche of electrons is used by lightning to discharge (see "Science and Life" No. 7, 1993).

Everyone who has seen lightning has noticed that it is not a brightly glowing straight line connecting the cloud and the earth, but a broken line. Therefore, the process of formation of a conductive channel for a lightning discharge is called its "step leader". Each of these "steps" is the place where the electrons accelerated to near-light speeds stopped due to collisions with air molecules and changed the direction of movement. Evidence for such an interpretation of the stepped character of lightning is the X-ray flashes coinciding with the moments when the lightning, as if stumbling, changes its trajectory. Recent studies have shown that lightning is a fairly powerful source of x-rays, the intensity of which can be up to 250,000 electron volts, which is about twice that used in chest x-rays.

How to trigger a lightning bolt? It is very difficult to study what will happen in an incomprehensible place and when. Namely, during years worked scientists investigating the nature of lightning. It is believed that the storm in the sky is led by Elijah the prophet and we are not given to know his plans. However, scientists have been trying to replace Elijah the prophet for a very long time, creating a conductive channel between a thundercloud and the earth. For this, B. Franklin launched a kite during a thunderstorm, ending in a wire and a bunch of metal keys. By doing this, he caused weak discharges flowing down the wire, and was the first to prove that lightning is a negative electrical discharge flowing from clouds to the ground. Franklin's experiments were extremely dangerous, and one of those who tried to repeat them - Russian academician G. V. Richman - in 1753 he died from a lightning strike.

In the 1990s, researchers learned how to summon lightning without endangering their lives. One way to cause lightning is to launch a small rocket from the ground directly into a thundercloud. Along the entire trajectory, the rocket ionizes the air and thus creates a conductive channel between the cloud and the ground. And if the negative charge of the bottom of the cloud is large enough, then a lightning discharge occurs along the created channel, all parameters of which are recorded by devices located near the rocket launch pad. To create more Better conditions for a lightning discharge, a metal wire is attached to the rocket, connecting it to the ground.

Lightning: the giver of life and the engine of evolution. In 1953, biochemists S. Miller (Stanley Miller) and G. Urey (Harold Urey) showed that one of the "building blocks" of life - amino acids can be obtained by passing an electric discharge through water, in which the gases of the "primitive" atmosphere of the Earth are dissolved ( methane, ammonia and hydrogen). Fifty years later, other researchers repeated these experiments and got the same results. Thus, scientific theory the origin of life on Earth assigns a fundamental role to the lightning strike.

When short current pulses are passed through bacteria, pores appear in their shell (membrane), through which DNA fragments of other bacteria can pass inside, triggering one of the mechanisms of evolution.

Why are thunderstorms so rare in winter? F. I. Tyutchev, having written “I love a thunderstorm in early May, when the first thunder in spring ...”, knew that there are almost no thunderstorms in winter. To form a thundercloud, ascending currents of moist air are needed. Concentration saturated vapors increases with temperature and reaches its maximum in summer. The temperature difference on which ascending air currents depend is the greater, the higher its temperature near the earth's surface, since at an altitude of several kilometers its temperature does not depend on the season. This means that the intensity of the ascending currents is also maximum in summer. Therefore, we have thunderstorms most often in summer, and in the north, where it is cold in summer, thunderstorms are quite rare.

Why are thunderstorms more common over land than over sea? In order for the cloud to discharge, there must be a sufficient number of ions in the air below it. Air, consisting only of nitrogen and oxygen molecules, does not contain ions, and it is very difficult to ionize it even in an electric field. But if there are a lot of foreign particles in the air, such as dust, then there are also a lot of ions. Ions are formed by the movement of particles in the air in the same way as they are electrified by rubbing against each other. various materials. Obviously, there is much more dust in the air over land than over oceans. That is why thunderstorms rumble over land more often. It has also been noted that, first of all, lightning strikes those places where the concentration of aerosols in the air is especially high - smoke and emissions from the oil refining industry.

How Franklin deflected lightning. Fortunately, most lightning strikes occur between clouds and therefore do not pose a threat. However, lightning is believed to kill more than a thousand people worldwide every year. By at least, in the United States, where such statistics are kept, about 1000 people are affected by lightning every year and more than a hundred of them die. Scientists have long tried to protect people from this "punishment of God." For example, the inventor of the first electric capacitor (Leiden jar), Pieter van Muschenbroek (1692-1761), in an article on electricity written for the famous French Encyclopedia, defended the traditional methods of preventing lightning - ringing bells and firing cannons, which, he believed, turned out to be quite efficient.

Benjamin Franklin, trying to protect the Capitol of the capital of Maryland, in 1775 attached a thick iron rod to the building, which towered several meters above the dome and was connected to the ground. The scientist refused to patent his invention, wishing that it would serve people as soon as possible.

The news of Franklin's lightning rod quickly spread throughout Europe, and he was elected to all academies, including the Russian one. However, in some countries, the devout population met this invention with indignation. The very idea that a person could so easily and simply tame the main weapon of "God's wrath" seemed blasphemous. Therefore, in different places, people broke lightning rods for pious reasons. A curious incident occurred in 1780 in the small town of Saint-Omer in northern France, where the townspeople demanded the removal of an iron lightning rod mast, and the case went to trial. The young lawyer who defended the lightning rod from the attacks of obscurantists built his defense on the fact that both the human mind and its ability to conquer the forces of nature have divine origin. Everything that helps to save a life is for the good - the young lawyer argued. He won the process and gained great fame. The lawyer's name was Maximilian Robespierre. Well, now the portrait of the inventor of the lightning rod is the most coveted reproduction in the world, because it adorns the well-known hundred-dollar bill.

How you can protect yourself from lightning with a water jet and a laser. Recently it has been proposed new way fight against lightning. A lightning rod will be created from ... a jet of liquid, which will be shot from the ground directly into thunderclouds. Lightning liquid is a saline solution to which are added liquid polymers: salt is designed to increase electrical conductivity, and the polymer prevents the jet from "breaking up" into separate droplets. The jet diameter will be about a centimeter, and maximum height- 300 meters. When the liquid lightning rod is finalized, it will be equipped with sports and playgrounds, where the fountain will turn on automatically when the electric field strength becomes high enough and the probability of a lightning strike is maximum. A charge will flow down a stream of liquid from a thundercloud, making lightning safe for others. A similar protection against a lightning discharge can be done with the help of a laser, the beam of which, by ionizing the air, will create a channel for an electric discharge away from crowds of people.

Can lightning lead us astray? Yes, if you use a compass. AT famous novel G. Melvila "Moby Dick" described just such a case when a lightning discharge, which created a strong magnetic field, remagnetized the compass needle. However, the ship's captain took a sewing needle, struck it to magnetize it, and replaced it with a broken compass needle.

Can you be struck by lightning inside a house or plane? Unfortunately yes! Lightning current can enter a house through a telephone wire from a nearby pole. Therefore, during a thunderstorm, try not to use a regular phone. It is believed that talking on a radiotelephone or on a mobile phone is safer. Do not touch pipes during thunderstorms central heating and plumbing that connects the house to the ground. For the same reasons, experts advise turning off everything during a thunderstorm. electrical devices including computers and televisions.

As for airplanes, generally speaking, they try to fly around areas with thunderstorm activity. And yet, on average, one of the planes is struck by lightning once a year. Its current cannot hit passengers, it flows down the outer surface of the aircraft, but it can disable radio communications, navigation equipment and electronics.

Fulgurite is petrified lightning. During a lightning discharge, 10 9 -10 10 joules of energy are released. Most of it is spent on creating shock wave(thunder), air heating, light flash and others electromagnetic waves, and only a small part stands out at the point where the lightning enters the ground. However, even this "small" part is quite enough to cause a fire, kill a person and destroy a building. Lightning can heat up the channel through which it travels up to 30,000 ° C, five times the temperature on the surface of the Sun. The temperature inside the lightning is much higher than the melting temperature of sand (1600-2000°C), but whether the sand melts or not also depends on the duration of the lightning, which can range from tens of microseconds to tenths of a second. The amplitude of the lightning current pulse is usually equal to several tens of kiloamperes, but sometimes it can exceed 100 kA. The most powerful lightning and cause the birth of fulgurites - hollow cylinders of melted sand.

The word "fulgurite" comes from the Latin fulgur, which means lightning. The longest of the excavated fulgurites went underground to a depth of more than five meters. Fulgurites are also called reflow solid rocks, formed by a lightning strike; they are sometimes in large numbers found on rocky mountaintops. Fulgurites, composed of remelted silica, are usually cone-shaped tubes as thick as a pencil or a finger. Them inner surface smooth and melted, and the outer one is formed by grains of sand adhering to the melted mass. The color of fulgurites depends on the mineral impurities in the sandy soil. Most of them are reddish brown, gray or black, but greenish, white or even translucent fulgurites are also found.

Apparently, the first description of fulgurites and their association with lightning strikes was made in 1706 by Pastor D. Hermann. Subsequently, many found fulgurites near people struck by lightning. Charles Darwin during world travel on the ship "Beagle", found on sandy shore near Maldonado (Uruguay) there are several glass tubes that go vertically down more than a meter into the sand. He described their size and connected their formation with lightning discharges. Famous American physicist Robert Wood got an "autograph" of the lightning bolt that nearly killed him:

“A strong thunderstorm passed, and the sky above us had already cleared up. I went through the field that separates our house from the house of my sister-in-law. I walked about ten yards along the path, when suddenly my daughter Margaret called me. I stopped for about ten seconds and barely moved farther on, when suddenly a bright blue line cut through the sky, with the roar of a twelve-inch gun, striking the path twenty paces in front of me and raising a huge column of steam. I went on to see what trace the lightning had left. burnt clover five inches in diameter, with a hole half an inch in the middle.... I went back to the laboratory, melted eight pounds of tin and poured into the hole... as it should be, in the handle and gradually converging towards the end. It was a little longer than three feet "(quoted by W. Seabrook. Robert Wood. - M .: Nauka, 1985, p. 285).

The appearance of a glass tube in the sand during a lightning discharge is due to the fact that there is always air and moisture between the grains of sand. The electric current of lightning in a split second heats up the air and water vapor to enormous temperatures, causing an explosive increase in air pressure between the grains of sand and its expansion, which Wood, who miraculously did not become a victim of lightning, heard and saw. The expanding air forms a cylindrical cavity inside the molten sand. Subsequent rapid cooling fixes fulgurite - a glass tube in the sand.

Often carefully excavated from the sand, fulgurite is shaped like a tree root or a branch with numerous processes. Such branched fulgurites are formed when a lightning discharge hits wet sand, which, as you know, has a higher electrical conductivity than dry sand. In these cases, the lightning current, entering the soil, immediately begins to spread to the sides, forming a structure similar to the root of a tree and the resulting fulgurite only repeats this shape.Fulgurite is very fragile, and attempts to remove adhering sand often lead to its destruction.This is especially true for branched fulgurites formed in wet sand.

Lightning

We often think that electricity is something that is generated only in power plants, and certainly not in the fibrous masses of water clouds, which are so rarefied that you can easily stick your hand into them. However, there is electricity in the clouds, as there is even in the human body.

Nature of electricity

All bodies are made up of atoms, from clouds and trees to human body. Every atom has a nucleus containing positively charged protons and neutral neutrons. The exception is simplest atom Hydrogen has no neutron in its nucleus, but only one proton.

Negatively charged electrons revolve around the nucleus. Positive and negative charges attract each other, so the electrons revolve around the nucleus of an atom, like bees around a sweet pie. The attraction between protons and electrons is due to electromagnetic forces. Therefore, electricity is present everywhere we look. As we can see, it is also contained in atoms.

AT normal conditions The positive and negative charges of each atom balance each other, so bodies made up of atoms usually carry no net charge, either positive or negative. As a result, contact with other objects does not cause an electrical discharge. But sometimes the balance of electric charges in bodies can be disturbed. You may experience this yourself when you are at home on a cold winter day. The house is very dry and hot. You, shuffling your bare feet, walk around the palace. Unbeknownst to you, some of the electrons from your soles have passed to the atoms of the carpet.

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Now you are carrying electric charge, since the number of protons and electrons in your atoms is no longer balanced. Now try to take hold of the metal door handle. A spark will fly between you and her, and you will feel an electric shock. This is what happened - your body, which does not have enough electrons to achieve electrical equilibrium, seeks to restore balance due to the forces of electromagnetic attraction. And it is being restored. There is a flow of electrons between the hand and the doorknob towards the hand. If the room were dark, you would see sparks. Light is visible because the electrons emit light quanta when they jump. If the room is quiet, you will hear a slight crackle.

Electricity surrounds us everywhere and is contained in all bodies. Clouds in this sense are no exception. On the background blue sky they look very harmless. But just like you are in a room, they can carry an electrical charge. If so, beware! When the cloud restores electrical balance within itself, a whole firework bursts out.

How does lightning appear?

Here's what happens: powerful air currents constantly circulate in a huge dark thundercloud, which push various particles together - grains of ocean salt, dust, and so on. In the same way that your soles are freed from electrons when rubbing against a carpet, and particles in a cloud are freed from electrons when they collide, which jump to other particles. So there is a redistribution of charges. Some particles that have lost their electrons have a positive charge, while others that have taken on extra electrons now have a negative charge.

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How does ball lightning appear?

For reasons that are not entirely clear, heavier particles are negatively charged, while lighter particles are positively charged. Thus, the heavier lower part of the cloud becomes negatively charged. The negatively charged lower part of the cloud repels electrons towards the ground, since like charges repel. Thus, a positively charged part is formed under the cloud earth's surface. Then, exactly according to the same principle, according to which a spark jumps between you and the doorknob, the same spark will jump between the cloud and the earth, only very large and powerful, this is lightning. Electrons fly in a giant zigzag towards the earth, finding their protons there. Instead of a barely audible crackle, swipe thunder.

Every second, approximately 700 lightning, and every year about 3000 people are killed by lightning strikes. physical nature Lightning has not been fully explained, and most people have only a rough idea of ​​what it is. Some discharges collide in the clouds, or something like that. Today we turned to our physics authors to learn more about the nature of lightning. How lightning appears, where lightning strikes, and why thunder rumbles. After reading the article, you will know the answer to these and many other questions.

What is lightning

Lightning- spark electric discharge in the atmosphere.

electrical discharge- this is the process of current flow in the medium, associated with a significant increase in its electrical conductivity relative to normal state. Exist different types electrical discharges in gas: spark, arc, smoldering.

The spark discharge occurs when atmospheric pressure and is accompanied by a characteristic crackle of a spark. A spark discharge is a collection of disappearing and replacing each other filamentous spark channels. Spark channels are also called streamers. The spark channels are filled with ionized gas, i.e. plasma. Lightning is a giant spark, and thunder is a very loud crack. But not everything is so simple.

The physical nature of lightning

How is the origin of lightning explained? System cloud-earth or cloud-cloud is a kind of capacitor. Air plays the role of a dielectric between clouds. The lower part of the cloud has a negative charge. With a sufficient potential difference between the cloud and the ground, conditions arise in which lightning occurs in nature.

Stepped leader

Before the main lightning flash, you can observe a small spot moving from the cloud to the ground. This is the so-called step leader. Electrons under the action of a potential difference begin to move towards the ground. As they move, they collide with air molecules, ionizing them. An ionized channel is being laid from the cloud to the ground. Due to the ionization of air by free electrons, the electrical conductivity in the zone of the leader trajectory increases significantly. The leader, as it were, paves the way for the main discharge, moving from one electrode (cloud) to another (ground). Ionization occurs unevenly, so the leader can branch out.

Backfire

The moment the leader approaches the ground, the tension at his end rises. From the ground or from objects protruding above the surface (trees, roofs of buildings), a response streamer (channel) is thrown towards the leader. This property of lightning is used to protect against them by installing a lightning rod. Why does lightning strike a person or a tree? In fact, she doesn't care where to hit. After all, lightning is looking for the shortest path between earth and sky. That is why during a thunderstorm it is dangerous to be on the plain or on the surface of the water.

When the leader reaches the ground, a current begins to flow through the laid channel. It is at this moment that the main lightning flash is observed, accompanied by a sharp increase in current strength and energy release. Here is the question, where does lightning come from? It is interesting that the leader spreads from the cloud to the ground, but the reverse bright flash, which we are used to seeing, spreads from the ground to the cloud. It is more correct to say that lightning does not go from heaven to earth, but occurs between them.

Why does lightning strike?

Thunder is the result of a shock wave generated by the rapid expansion of ionized channels. Why do we see lightning first and then hear thunder? It's all about the difference in the speeds of sound (340.29 m/s) and light (299,792,458 m/s). By counting the seconds between thunder and lightning and multiplying them by the speed of sound, you can find out at what distance the lightning struck from you.

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Types of lightning and facts about lightning

Lightning between heaven and earth is not the most common lightning. Most often, lightning occurs between clouds and does not pose a threat. In addition to terrestrial and intracloud lightning, there are lightnings that form in the upper atmosphere. What are the types of lightning in nature?

• Intra-cloud lightning;
• Ball lightning;
• "Elves";
• Jets;
• Sprites.

The last three types of lightning cannot be observed without special devices, since they are formed at an altitude of 40 kilometers and above.

Here are the facts about lightning:

• The length of the longest recorded lightning on Earth was 321 km. This lightning was seen in Oklahoma, 2007.
• The longest lightning lasted 7,74 seconds and was recorded in the Alps.
• Lightning is formed not only on Earth. Know exactly about lightning on Venus, Jupiter, Saturn and Uranus. Saturn's lightning is millions of times more powerful than Earth's.
• The current in lightning can reach hundreds of thousands of amperes, and the voltage can reach billions of volts.
• The temperature of the lightning channel can reach 30000 degrees Celsius is 6 times the surface temperature of the sun.

Fireball

Fireball - separate view lightning, the nature of which remains a mystery. Such lightning is a moving in the air luminous object in the form of a ball. According to few testimonies fireball it can move along an unpredictable trajectory, split into smaller lightning bolts, it can explode, or it can simply disappear unexpectedly. There are many hypotheses about the origin of ball lightning, but none can be recognized as reliable. The fact is that no one knows how ball lightning appears. Some hypotheses reduce the observation of this phenomenon to hallucinations. Ball lightning has never been observed in the laboratory. All scientists can be content with is eyewitness accounts.

Finally, we invite you to watch the video and remind you: if the course paper or control fell on your head like lightning on a sunny day, do not despair. Student Services Specialists have been helping students since 2000. Seek qualified help at any time. 24 hours a day, 7 days a week we are ready to help you.

Lightning is a delightful and exciting natural phenomenon. At the same time, it is one of the most dangerous and unpredictable natural phenomena. But what do we really know about lightning? Scientists around the world are collecting lightning facts, try to reproduce them in their laboratories, measure their power and temperature, but still are not able to determine the nature of lightning and predict its behavior. But still, let's look at Interesting Facts about lightning, which are already known.

At this moment, about 1800 thunderstorms are raging in the world.

Every year, the Earth experiences an average of 25 million lightning strikes or over a hundred thousand thunderstorms. That's more than 100 lightning strikes per second.

An average lightning strike lasts a quarter of a second.

You can hear thunder 20 kilometers away from lightning.

The lightning discharge propagates at a speed of about 190,000 km/s.

The average length of a lightning discharge is 3-4 kilometers.

Some lightning travels in the air in a twisted path, which may not exceed the thickness of your finger in diameter, and the length of the lightning path will be 10-15 kilometers.

The temperature of a typical lightning can exceed 30,000 degrees Celsius - that's about 5 times the surface temperature of the sun.

"Lightning never strikes the same place twice." Unfortunately, this is a myth. Lightning often strikes the same place multiple times.

The ancient Greeks believed that when lightning strikes the sea, a new pearl appears.

Trees can sometimes take lightning strikes and still not catch fire. This is because the electricity passes through the wet surface straight into the ground.

When lightning strikes, the sand turns into glass. After a thunderstorm, you can find glass streaks in the sand.

If your clothes are wet, then the lightning will do you less harm.

During a 6-hour thunderstorm across the United States, 15,000 lightning bolts sparkled in the sky. There was a feeling that the lightning was constantly burning.

The tallest building in the world, the CN Tower, is struck by lightning about 78 times a year.

Lightning flashes can also be seen on Venus, Jupiter, Saturn and Uranus.

In the Middle Ages, it was believed that thunder and lightning were the offspring of the devil, and church bells scare away evil spirits. Therefore, during a thunderstorm, the monks constantly tried to ring the bells, and, accordingly, most often became victims of lightning.

The irrational fear of lightning is called keraunophobia. Fear of thunder - brontophobia.

There are between 100 and 1000 instances of ball lightning on Earth at the same time, but the chance that you will see at least one of them is 0.01%.

On average, about 550 people die from lightning strikes in Russia.

Approximately a quarter of all people who have become victims of lightning die.

Men are killed by lightning about 6 times more often than women.

The telephone is one of the most common causes of a person being struck by lightning. Do not talk on the phone during a thunderstorm, even indoors. After a lightning strike, branched stripes remain on the human body - signs of lightning. Disappear when pressed with a finger.

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The long-awaited retreat of the heat is accompanied by severe thunderstorms. Petersburg for last week two powerful thunderstorms swept through. The sight was terrible. The sky seemed to crack and tear apart, lightning flashes like explosions.
Why does such a thunderstorm arise, how does it originate in the atmosphere? Such questions come to mind precisely in this stormy time. Let's try to figure it out, relying on competent sources. As you will see that temperature plays an important role here.

Where do thunderstorms most often occur?

Over the continents in the tropics. There are an order of magnitude fewer thunderstorms over the ocean. One of the reasons for this asymmetry is the intense convection in continental regions, where the land is effectively warmed up. solar radiation. The rapid rise of heated air contributes to the formation of powerful convective vertical clouds, in the upper part of which the temperature is below -40°C. As a result, particles of ice, snow pellets, hail are formed, the interaction of which against the background of a fast upward flow leads to charge separation.

Approximately 78% of all lightning strikes occur between 30°S. and 30°N. Maximum average density the number of outbreaks per unit of the Earth's surface is observed in Africa (Rwanda). The entire basin of the Congo River with an area of ​​about 3 million km 2 regularly demonstrates the highest lightning activity.

How is a thundercloud charged?

This is the most interest Ask in "thunderstorm". Thunderclouds are huge. In order for an electric field comparable in magnitude to a breakdown field (about 30 kV/cm for air under normal conditions) to arise on a scale of several kilometers, it is necessary that the random exchange of charges during collisions of cloudy solid or liquid particles lead to a consistent, collective effect of adding microcurrents into macroscopic current of a very large value (several amperes). As shown by measurements of the electric field on the earth's surface, as well as inside the cloudy medium (on balloons, aircraft and rockets), in a typical thundercloud the "main" negative charge - on average several tens of coulombs - occupies a height interval corresponding to temperatures from 10 to 25 ° C. The "main" positive charge is also several tens of pendants, but is located above the main negative, therefore most of lightning discharges cloud-earth gives the earth a negative charge. However, a smaller (10 C) positive charge is also often found at the bottom of the cloud.

To explain the (tripole) structure of the field and charge in a thundercloud described above, a variety of charge separation mechanisms are considered. They depend primarily on factors such as temperature and phase composition of the medium. Despite the abundance of various microphysical mechanisms of electrification, many authors now consider the main non-inductive charge exchange during collisions of small (with sizes from units to tens of micrometers) ice crystals and snow grain particles. AT laboratory experiments was found to have characteristic value temperature at which the sign of the charge changes, the so-called. reversal point, usually between 15 and 20°C. It was this feature that made this mechanism so popular because, given the typical temperature profile in the cloud, it explains the tripole structure of the charge density distribution.

Recent experiments have shown that many thunderclouds are even more complex structure space charge (up to six layers). Updrafts in such clouds can be weak, but the electric field has a stable multilayer structure. Near the zero isotherm (0 °C), quite narrow (several hundred meters thick) and stable space charge layers are formed here, which are largely responsible for the high lightning activity. The question of the mechanism and patterns of layer formation positive charge in the vicinity of the zero isotherm remains debatable. The model developed at the IAP, based on the mechanism of charge separation during the melting of ice particles, confirms the formation of a positive charge layer during the melting of ice particles near the zero isotherm at a height of about 4 km. Calculations showed that a field structure with a maximum of about 50 kV/m is formed in 10 minutes.

How does lightning strike?

There are several theories. Recently, a new lightning scenario has been proposed and studied, which is associated with the achievement of self-organized criticality by the cloud. In the model of electric cells (with a characteristic size of ~1–30 m) with a potential that randomly grows in space and time, a separate small-scale breakdown between a pair of cells can cause an “epidemic” of intracloud microdischarges - stochastic process fractal "metallization" of the intracloud environment, i.e. a rapid transition of the cloud environment to a state resembling a voluminous web of dynamic conductive threads, against which the visible to the eye lightning channel - a conductive plasma channel through which the main electric charge is transferred

According to some ideas, the discharge is initiated by high-energy cosmic rays, which trigger a process called runaway breakdown. Interestingly, the presence of a cellular structure of the electric field in a thundercloud turns out to be essential for the process of electron acceleration to relativistic energies. Randomly oriented electric cells, along with acceleration, sharply increase the lifetime of relativistic electrons in a cloud due to the diffusion nature of their trajectories. This makes it possible to explain the significant duration of X-ray and gamma-ray bursts and the nature of their relationship with lightning flashes. Role cosmic rays for atmospheric electricity should be clarified by experiments to investigate their correlation with thunderstorms. Such experiments are currently being carried out in the Tien Shan high mountain scientific station Physical Institute of the Russian Academy of Sciences and at the Baksan Neutrino Observatory of the Institute nuclear research RAN.

We also note that the discharge phenomena in the middle atmosphere, which correlate with thunderstorm activity, have received different names depending on the height above the Earth. These are sprites (the glow area extends from heights of 50-55 km to 85-90 km above the ground, and the duration of the flash is from a few to tens of milliseconds), elves (heights - 70-90 km, duration less than 100 μs) and jets (discharges, clouds that start in the upper part and sometimes propagate to mesospheric heights at a speed of about 100 km/s).

Lightning temperature

In the literature, one can find data that the temperature of the lightning channel during the main discharge can exceed 25,000 °C. Clear evidence that the temperature of lightning can reach 1700 ° C is found on the rocky peaks of mountains and in areas with strong thunderstorm activity fulgurites (from Latin fulgur - lightning strike) - quartz tubes sintered from a lightning strike, which can be of various bizarre shapes.

The photo shows a fulgurite found in 2006 in Arizona, USA (details at www.notjustrocks.com). The appearance of a glass tube is due to the fact that there is always air and moisture between the grains of sand. The electric current of lightning in a fraction of a second heats the air and water vapor to enormous temperatures, causing an explosive increase in air pressure between the grains of sand and its expansion. The expanding air forms a cylindrical cavity inside the molten sand. Subsequent rapid cooling fixes fulgurite - a glass tube in the sand. Fulgurites, composed of remelted silica, are usually cone-shaped tubes as thick as a pencil or a finger. Their inner surface is smooth and melted, and the outer surface is formed by grains of sand and foreign inclusions adhering to the melted mass. The color of fulgurites depends on the mineral impurities in the sandy soil. Fulgurite is very brittle, and attempts to remove adhering sand often lead to its destruction. This is especially true for branched fulgurites formed in wet sand. The diameter of the tubular fulgurite is no more than a few centimeters, the length can reach several meters; fulgurite was found 5-6 meters long.

The study of lightning and atmospheric electricity in general is very interesting and important. scientific direction. Numerous publications have been published on this topic. scientific papers and popular articles. A link to one of the most comprehensive review papers is given at the end of our note.

In conclusion, I would like to note that lightning is a serious threat to human life. The defeat of a person or animal by lightning often occurs in open spaces, since electricity goes along the shortest way"storm cloud-earth". Lightning often hits trees and transformer installations on railway causing them to ignite. It is impossible to be struck by ordinary linear lightning inside a building, however, there is an opinion that the so-called ball lightning can penetrate through cracks and open windows. Ordinary lightning is dangerous for television and radio antennas located on rooftops. high-rise buildings, as well as for network equipment.