Physics of the atmosphere: how, why and where lightning comes from. Lightning (phenomenon) The optical phenomenon of lightning

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Lightning as a natural phenomenon

Lightning is a giant electrical spark between clouds or between clouds and earth's surface several kilometers long, tens of centimeters in diameter, and tenths of a second long. Lightning is accompanied by thunder. In addition to linear lightning, ball lightning is occasionally observed.

The nature and causes of lightning

A thunderstorm is a complex atmospheric process, and its occurrence is due to the formation of cumulonimbus clouds. Strong cloudiness is a consequence of the significant instability of the atmosphere. Thunderstorms are characterized strong wind, often heavy rain (snow), sometimes with hail. Before a thunderstorm (an hour or two before a thunderstorm) Atmosphere pressure begins to fall rapidly until the wind suddenly increases, and then begins to rise.

Thunderstorms can be divided into local, frontal, night, in the mountains. Most often, a person encounters local or thermal thunderstorms. These thunderstorms only occur during hot weather with high humidity. atmospheric air. As a rule, they occur in the summer at noon or afternoon (12-16 hours). The water vapor in the ascending stream of warm air condenses at a height, while a lot of heat is released and the ascending air streams are heated. The rising air is warmer than the surrounding air and expands until it becomes a thundercloud. Large storm clouds are constantly filled with ice crystals and water droplets. As a result of their crushing and friction between themselves and against the air, positive and negative charges are formed, under the influence of which a strong electrostatic field arises (tension electrostatic field can reach 100,000 V/m). And the potential difference between the individual parts of the cloud, the clouds or the cloud and the earth reaches enormous values. When the critical tension of the electric air is reached, an avalanche-like air ionization occurs - a spark discharge of lightning.

A frontal thunderstorm occurs when cold air masses enter an area dominated by warm weather. Cold air displaces warm air, while the latter rises to a height of 5-7 km. Warm layers of air invade the vortices different orientation, a squall is formed, strong friction between the layers of air, which contributes to the accumulation electric charges. The length of a frontal thunderstorm can reach 100 km. Unlike local thunderstorms, it usually gets colder after frontal thunderstorms. A night thunderstorm is associated with the cooling of the earth at night and the formation of eddy currents of the ascending air. The thunderstorm in the mountains is explained by the difference in solar radiation, which are exposed to the southern and northern slopes of the mountains. Night and mountain thunderstorms are not strong and short.

Thunderstorm activity in different regions of our planet is different. World hotspots of thunderstorms: Java island - 220, Equatorial Africa-150, Southern Mexico - 142, Panama - 132, Central Brazil - 106 thunderstorm days a year. Russia: Murmansk - 5, Arkhangelsk - 10, St. Petersburg - 15, Moscow - 20 thunderstorm days a year.

By type of lightning are divided into linear, pearl and ball. Pearl and ball lightning is quite rare.

The lightning discharge develops in a few thousandths of a second; at such high currents, the air in the zone of the lightning channel almost instantly heats up to a temperature of 30,000-33,000 ° C. As a result, the pressure rises sharply, the air expands - a shock wave occurs, accompanied by a sound impulse - thunder. Due to the fact that on high pointed objects the electric field strength created by the static electric charge of the cloud is especially high, a glow occurs; as a result, air ionization begins, a glow discharge occurs and reddish glow tongues appear, sometimes shortening and again lengthening. Do not attempt to extinguish these fires, as there is no combustion. At a high electric field strength, a beam of luminous filaments may appear - a corona discharge, which is accompanied by a hiss. Linear lightning can also occasionally occur in the absence of thunderclouds. It is no coincidence that the saying arose - "thunder from a clear sky."

The discovery of ball lightning

lightning discharge ball electric

As often happens, the systematic study of ball lightning began with a denial of their existence: in early XIX century, all isolated observations known by that time were recognized as either mysticism or, at best, an optical illusion.

But already in 1838, a survey compiled by the famous astronomer and physicist Dominique Francois Arago was published in the Yearbook of the French Bureau of Geographic Longitudes. Subsequently, he initiated the experiments of Fizeau and Foucault to measure the speed of light, as well as the work that led Le Verrier to the discovery of Neptune. Based on the then known descriptions of ball lightning, Arago came to the conclusion that many of these observations cannot be considered an illusion. In the 137 years that have passed since the publication of Arago's review, new eyewitness accounts and photographs have appeared. Dozens of theories were created, extravagant, witty, such that explained some known properties ball lightning, and those that could not withstand elementary criticism. Faraday, Kelvin, Arrhenius, Soviet physicists Ya.I. Frenkel and P.L. Kapitsa, many well-known chemists, and finally, specialists from the American National Commission for Astronautics and Aeronautics, NASA tried to investigate and explain this interesting and formidable phenomenon. And ball lightning still continues to be largely a mystery.

The nature of ball lightning

What facts should scientists connect unified theory to explain the nature of the occurrence of ball lightning? What are the limitations of observation on our imagination?

In 1966, NASA circulated a questionnaire to 2,000 people, the first part of which asked two questions: "Have you seen ball lightning?" and “Have you seen a linear lightning strike in the immediate vicinity?” The answers made it possible to compare the frequency of observation of ball lightning with the frequency of observation of ordinary lightning. The result turned out to be stunning: 409 out of 2,000 people saw a linear lightning strike near, and two times less than a ball lightning. There was even a lucky person who met ball lightning 8 times - one more circumstantial evidence that this is not at all as rare as it is commonly thought.

Analysis of the second part of the questionnaire confirmed many previously known facts: ball lightning has an average diameter of about 20 cm; does not glow very brightly; the color is most often red, orange, white. Interestingly, even observers who saw ball lightning up close often did not feel its thermal radiation, although it burns when touched directly.

There is such lightning from a few seconds to a minute; can penetrate into the premises through small holes, then restoring its shape. Many observers report that it throws out some kind of sparks and rotates. It usually hovers a short distance from the ground, although it has also been seen in the clouds. Sometimes ball lightning quietly disappears, but sometimes it explodes, causing noticeable destruction.

Ball lightning carries a lot of energy. True, deliberately overestimated estimates are often found in the literature, but even a modest realistic figure - 105 joules - is very impressive for a lightning bolt with a diameter of 20 cm. If such energy were spent only on light radiation, it could glow for many hours. Some scientists believe that lightning is constantly receiving energy from outside. For example, P.L. Kapitsa suggested that it occurs when a powerful beam of decimeter radio waves is absorbed, which can be emitted during a thunderstorm. In reality, for the formation of an ionized bunch, which is ball lightning in this hypothesis, the existence of standing wave electromagnetic radiation with a very high field strength at the antinodes. During the explosion of ball lightning, a power of a million kilowatts can develop, since this explosion proceeds very quickly. Explosions, however, a person can arrange even more powerful ones, but if compared with “calm” energy sources, then the comparison will not be in their favor.

Why ball lightning glows

Let us dwell on one more riddle of ball lightning: if its temperature is low (in the cluster theory it is considered that the temperature of ball lightning is about 1000°K), then why does it glow? It turns out that this can be explained.

During the recombination of clusters, the released heat is rapidly distributed among colder molecules. But at some point, the temperature of the “volume” near the recombined particles can exceed average temperature matter lightning more than 10 times. This "volume" glows like a gas heated to 10,000-15,000 degrees. There are relatively few such "hot spots", so the substance of ball lightning remains translucent. The color of ball lightning is determined not only by the energy of the solvate shells and the temperature of the hot "volumes", but also by the chemical composition of its substance. It is known that if ball lightning appears when linear lightning strikes copper wires, it is often colored blue or green - the usual "colors" of copper ions. Residual electric charge can explain such interesting properties ball lightning, as its ability to move against the wind, be attracted to objects and hang over high places.

Cause of ball lightning

To explain the conditions for the occurrence and properties of ball lightning, researchers have proposed many different hypotheses. One of the extraordinary hypotheses is the alien theory, which proceeds from the assumption that ball lightning is nothing but a type of UFO. This assumption has a basis, since many eyewitnesses claim that ball lightning behaved like a living thing. sentient being. Most often, it looks like a ball, which is why in the old days it was called fireball. However, this is not always the case: variants of ball lightning also occur. It can be the shape of a mushroom, a jellyfish, a donut, a drop, a flat disk, an ellipsoid. The color of lightning is most often yellow, orange or red, white, blue, green, black is less common. The appearance of ball lightning does not depend on the weather. They may occur in different weather and completely independent of power lines. A meeting with a person or animal can also take place in different ways: mysterious balls either hover peacefully at some distance, or attack with fury, causing burns or even killing. After that, they may quietly disappear or explode loudly. It should be noted that the number of people killed and injured from fiery objects is approximately 9% of total number witnesses. In the case of a person being struck by ball lightning, in many cases there are no traces left on the body, and the body of the person killed by lightning for an inexplicable reason for a long time does not decompose. In connection with this circumstance, a theory appeared that lightning is able to influence the course of the individual time of the organism.

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What is lightning?

What is lightning? This is an amazing and very mysterious phenomenon of nature. It almost always happens during a thunderstorm. Some people are amazed, some people are scared. Poets write about lightning, scientists study this phenomenon. But much remains unsolved.

One thing is known for sure - it's a giant spark. Like a billion light bulbs exploded! Its length is huge - several hundred kilometers! And it is very far from us. That is why we first see it, and only then we hear it. Thunder is the "voice" of lightning. After all, light reaches us faster than sound.

And there are lightning on other planets. For example, on Mars or Venus. Normal lightning lasts only a fraction of a second. It consists of several categories. Lightning appears sometimes quite unexpectedly.

How is lightning formed?

Lightning is usually born in a thundercloud, high above the ground. Thunderclouds appear when the air starts to get very hot. That's why after a heat wave there are amazing thunderstorms. Billions of charged particles literally flock to the place where it originates. And when there are very, very many of them, they flare up. That's where lightning comes from - from a thundercloud. She can hit the ground. The earth draws her. But it can break in the cloud itself. It all depends on what kind of lightning it is.

What are lightning bolts?

There are different types of lightning. And you need to know about it. This is not only a "ribbon" in the sky. All these "ribbons" are different from each other.

Lightning is always a strike, it is always a discharge between something. There are more than ten of them! For now, we will name only the most basic ones, attaching pictures of lightning to them:

Between thundercloud and earth. These are the very "ribbons" to which we are accustomed.

Between tall tree and cloud. The same "ribbon", but the blow is directed in the other direction.

Tape lightning - when not one "ribbon", but several in parallel.

Between cloud and cloud, or simply “play out” in one cloud. This type of lightning is often seen during thunderstorms. You just need to be careful.

There are also horizontal lightnings that do not touch the ground at all. They are endowed with colossal strength and are considered the most dangerous

Everyone has heard of ball lightning! Few people have seen them. There are even fewer who would like to see them. And there are people who do not believe in their existence. But fireballs do exist! Photographing such lightning is difficult. It explodes quickly, although it can “walk”, but it’s better for a person next to her not to move - it’s dangerous. So - not up to the camera here.

Kind of lightning with a very beautiful name- St. Elmo's Fire. But it's not really lightning. This is the glow that appears at the end of a thunderstorm on pointed buildings, lanterns, ship masts. Also a spark, only not damped and not dangerous. The fires of St. Elmo are very beautiful.

Volcanic lightning occurs when a volcano erupts. The volcano itself already has a charge. This is probably what causes lightning.

Sprite lightning is something you can't see from Earth. They arise above the clouds and so far few people have been studying them. These lightning bolts look like jellyfish.

Dotted lightning is almost not studied. It is extremely rare to see it. Visually, it really looks like a dotted line - as if the lightning-ribbon is melting.

These are the different types of lightning. There is only one law for them - an electric discharge.

Conclusion.

Even in ancient times, lightning was considered both a sign and the fury of the Gods. She was a mystery before and remains so now. No matter how they decompose it into the smallest atoms and molecules! And it's always amazingly beautiful!

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 of atoms - from clouds and trees to the human body. Every atom has a nucleus containing positively charged protons and neutral neutrons. The exception is the simplest hydrogen atom, in the nucleus of which there is no neutron, 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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A little about the weather

Now you are carrying an electrical charge, as 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.

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Why are lightning bolts different colors?

How does lightning appear?

This is 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 by rubbing against a carpet, and particles in a cloud are freed from electrons by collision, 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 are now negative charge.

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 of the earth's surface is formed under the cloud. 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.

Lightning - natural gas discharge

Introduction3

1.Historical views on lightning 4

2. Lightning 6

Types of lightning9

Physics of linear lightning9

Riddle of ball lightning ……………………………………………...13

3. Ranks 26

Types of discharges26

spark discharge2 6

4. Lightning protection 33

Conclusion3 7

List of usesovannoyliterature39

Introduction

The choice of the topic of my essay is due not only to personal interest, but also to relevance. The nature of lightning is fraught with many mysteries. When describing this rare phenomenon, scientists are forced to rely only on scattered eyewitness accounts. These meager stories, and a handful of photographs - that's all that science has. As one scientist stated, we know no more about lightning than the ancient Egyptians knew about the nature of stars.

Lightning is of great interest not only as a peculiar phenomenon of nature. It makes it possible to observe an electric discharge in a gaseous medium at a voltage of several hundred million volts and a distance between the electrodes of several kilometers. The purpose of this essay is to consider the causes of lightning, the study various kinds electric charges. The issue of lightning protection is also considered in the abstract. People have long understood the harm that a lightning strike can bring, and have come up with protection from it.

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 we were able to detect them even on other planets.

2. Historical views on lightning

Lightning and thunder were originally perceived by people as an expression of the will of the gods and, in particular, as a manifestation of God's wrath. At the same time, the inquisitive human mind has long tried to comprehend the nature of lightning and thunder, to understand their natural causes. In ancient times, Aristotle thought about this. Lucretius thought about the nature of lightning. His attempts to explain the thunder as a consequence of the fact that "the clouds collide there under the pressure of the winds" seem very naive.

For many centuries, including the Middle Ages, it was believed that lightning is a fiery vapor trapped in the water vapor of clouds. Expanding, it breaks through them in the weakest place and quickly rushes down to the surface of the earth.

In 1752, Benjamin Franklin (Fig. 1) experimentally proved that lightning is a strong electrical discharge. The scientist performed the famous experiment with a kite, which was launched into the air when a thunderstorm approached.

Experiment: A pointed wire was fastened to the cross of the snake, a key and a silk ribbon were tied to the end of the rope, which he held with his hand. As soon as the thundercloud was above the kite, the pointed wire began to extract an electric charge from it, and the kite, along with the towline, became electrified. After the rain wets the kite and string, thus making them free to conduct an electric charge, one can observe how the electric charge will "drain" when the finger approaches.

Simultaneously with Franklin, M.V. Lomonosov and G.V. Richman.

Thanks to their research in the middle of the 18th century, it was proved electrical nature lightning. Since that time, it has become clear that lightning is a powerful electrical discharge that occurs when the clouds are sufficiently electrified.

Lightning

Lightning is an eternal source of recharging the Earth's electric field. At the beginning of the 20th century, atmospheric probes measured electric field 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 an electrically conductive layer, the ionosphere, was formed under the action of cosmic radiation. 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 1-12 A/m2, and energy up to 1.5 GW is released. And this electric field would disappear if there were no lightning! Therefore, in good weather an electric capacitor - Earth - is discharged, and during a thunderstorm it is charged.

Lightning is a natural discharge of large accumulations of electric charge in the lower atmosphere. One of the first to establish this was the American statesman and scientist B. Franklin. In 1752, he experimented with a kite, to the cord of which a metal key was attached, and received sparks from the key during a thunderstorm. Since then, lightning has been intensively studied as interesting phenomenon nature, as well as due to serious damage to power lines, houses and other buildings caused by a direct lightning strike or voltage induced by it.

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 long tried to replace Elijah the prophet by creating a conductive channel between a thundercloud and the earth. B. Franklin for this during a thunderstorm launched kite, ending with 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, the Russian academician G. V. Richman, died in 1753 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.

The cloud is a factory for the production of electric charges. 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 is different. 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, the clouds consist of ice floes of different sizes, since the temperature there is always below zero. These ice floes are in constant motion, caused by ascending 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 ice floes, moving to the upper part of the cloud, 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 is a "hello" from space and a source of x-rays. However, the cloud itself is not able to electrify itself so as to cause a discharge between its lower part and the earth. The electric field strength in a thundercloud never exceeds 400 kV/m, and electrical breakdown in air occurs at a strength 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 the Physical Institute. P. N. Lebedeva 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 electrons that have high energy. 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.

Recent studies have shown that lightning is a fairly powerful source of X-ray radiation, the intensity of which can be up to 250,000 electron volts, which is about twice that used in chest x-rays.

Types of lightning

a) Most lightning occurs between clouds and the ground, however, there are lightnings that occur between clouds. All these lightnings are called linear. The length of an individual linear lightning can be measured in kilometers.

b) Another type of lightning is tape lightning (Fig. 2). In this case, the following picture, as if there were several almost identical linear lightning shifted relative to each other.

c) It was noticed that in some cases the flash of lightning breaks up into separate luminous sections several tens of meters long. This phenomenon is called bead lightning. According to Malan (1961), this type of lightning is explained on the basis of a protracted discharge, after which the glow would seem to be brighter in the place where the channel bends in the direction of the observer, observing it with its end towards itself. And Youman (1962) believed that this phenomenon should be considered as an example of the "ping effect", which consists in a periodic change in the radius of the discharge column with a period of several microseconds.

d) Ball lightning, which is the most mysterious natural phenomenon.

Physics of linear lightning

Linear lightning is a series of pulses rapidly following each other. Each impulse is a breakdown of the air gap between the cloud and the ground, occurring in the form spark discharge. Let's look at the first impulse first. There are two stages in its development: first, a discharge channel is formed between the cloud and the ground, and then a main current pulse quickly passes through the formed channel.

The first stage is the formation of a discharge channel. It all starts with the fact that an electric field of very high intensity is formed in the lower part of the cloud - 105 ... 106 V / m.

Free electrons receive huge accelerations in such a field. These accelerations are directed downwards, since the lower part of the cloud is negatively charged, while the surface of the earth is positively charged. On the way from the first collision to the next, electrons acquire a significant kinetic energy. Therefore, colliding with atoms or molecules, they ionize them. As a result, new (secondary) electrons are born, which, in turn, are accelerated in the cloud field and then ionize new atoms and molecules in collisions. Entire avalanches of fast electrons arise, forming clouds at the very "bottom", plasma "threads" - a streamer.

Merging with each other, the streamers give rise to a plasma channel, through which the main current pulse subsequently passes.

This plasma channel, which develops from the "bottom" of the cloud to the surface of the earth, is filled with free electrons and ions, and therefore can conduct electric current well. He is called leader or more precisely step leader. The fact is that the channel is not formed smoothly, but in jumps - “steps”.

Why there are pauses in the leader's movement and, moreover, relatively regular ones, is not exactly known. There are several theories of step leaders.

In 1938 Schonlund put forward two possible explanations for the delay that causes the stepping nature of the leader. According to one of them, there should be a movement of electrons down the channel lead streamer (drankaboutthat). However, some of the electrons are captured by atoms and positively charged ions, so that it takes some time for new advancing electrons to enter before a potential gradient is created that is sufficient for the current to continue. According to another point of view, it takes time for positively charged ions to accumulate under the head of the leader channel and thus create a sufficient potential gradient across it. But physical processes occurring near the head of the leader are quite understandable. The field strength under the cloud is quite large - it is<
b/m; in the region of space directly in front of the leader's head, it is even greater. In a strong electric field near the leader head, intense ionization of air atoms and molecules occurs. It occurs due, firstly, to the bombardment of atoms and molecules by fast electrons emitted from the leader (the so-called impact ionization), and, secondly, the absorption by atoms and molecules of photons of ultraviolet radiation emitted by the leader (photoionization). Due to the intense ionization of the air atoms and molecules encountered on the leader's path, the plasma channel grows, and the leader moves towards the earth's surface.>

Taking into account the stops along the way, it took the leader 10…20 ms to reach the ground at a distance of 1 km between the cloud and the ground surface. Now the cloud is connected to the ground by a plasma channel, which perfectly conducts current. The channel of ionized gas, as it were, short-circuited the cloud with the earth. This completes the first stage of development of the initial impulse.

Second stage runs fast and powerful. The main current rushes along the path laid by the leader. The current pulse lasts approximately 0.1ms. The current strength reaches values of the order<
A. A significant amount of energy is released (up to
J). The gas temperature in the channel reaches
. It is at this moment that the extraordinarily bright light that we observe in a lightning discharge is born, and thunder occurs, caused by the sudden expansion of a suddenly heated gas.>

It is essential that both the glow and the heating of the plasma channel develop in the direction from the ground to the cloud, i.e. upwards. To explain this phenomenon, we conditionally divide the entire channel into several parts. As soon as the channel is formed (the head of the leader has reached the ground), first of all, the electrons that were in its lowest part jump down; therefore, the lower part of the channel is the first to glow and warm up. Then electrons from the next (higher up part of the channel) rush to the ground; the glow and heating of this part begin. And so gradually - from the bottom to the top - more and more electrons are included in the movement to the ground; as a result, the glow and heating of the channel propagate in the upward direction.

After the main current pulse has passed, there is a pause

duration from 10 to 50ms. During this time, the channel practically goes out, its temperature drops to approximately<
, the degree of channel ionization decreases significantly.>

If more time than usual passes between successive lightning strikes, the degree of ionization can be so low, especially in the lower part of the channel, that a new pilot is needed to re-ionize the air. This explains individual cases of the formation of steps at the lower ends of the leaders, preceding not the first but subsequent main lightning strikes.

As discussed above, the new leader follows the path that was blazed by the original leader. It runs all the way from top to bottom without stopping (1ms). And again follows a powerful pulse of the main current. After another pause, everything repeats. As a result, several powerful impulses are displayed, which we naturally perceive as single rank lightning, as a single bright flash (Fig. 3).

Ball Lightning Mystery

Ball lightning is absolutely different from ordinary (linear) lightning, neither in its appearance nor in the way it behaves. Ordinary lightning is short-lived; ball lives tens of seconds, minutes. Ordinary lightning is accompanied by thunder; ball is almost silent, its behavior has a lot of unpredictability (Fig. 4).

Ball lightning asks us a lot of mysteries, questions to which there is no clear answer. At present, one can only speculate and make hypotheses.

The only method for studying ball lightning is the systematization and analysis of random observations.

Observation Processing Results

Here is the most reliable information about ball lightning (BL)

CMM is a spherical object with a diameter of 5 ... 30 cm. The shape of the CMM changes slightly, taking pear-shaped or flattened spherical outlines. Very rarely, BL was observed in the form of a torus.

CMM glows usually orange, cases of violet color are noted. The brightness and nature of the glow are similar to the glow of incandescent charcoal, sometimes the intensity of the glow is compared with a weak electric light bulb. Against the background of homogeneous radiation, more brightly luminous regions (glare) appear and move.

The lifetime of BL is from a few seconds to ten minutes. The existence of CMM ends with its disappearance, sometimes accompanied by an explosion or a bright flash that can cause a fire.

CMM is usually observed during a thunderstorm with rain, but there is anecdotal evidence of the observation of CMM during a thunderstorm without rain. There have been cases of observations of CMM over water bodies at a considerable distance from the coast or any objects.

CMM floats in the air and moves along with air currents, but at the same time it can make “strange” active movements that clearly do not coincide with the movement of air.

When colliding with surrounding objects, the BL bounces like a weakly inflated balloon or ends its existence.

Upon contact with steel objects, the CMM is destroyed, and a bright flash lasting several seconds is observed, accompanied by flying luminous fragments resembling metal welding. Steel objects upon subsequent inspection are slightly melted.

CMM sometimes enters the premises through closed windows. Most witnesses describe the penetration process as pouring through a small hole, a very small part of the witnesses claim that CMM penetrates through intact window glass, while practically not changing its shape.

With a brief touch of the CMM on human skin, minor burns are recorded. Severe burns and even death were recorded at contacts that ended in a flash or explosion.

Significant changes in the size of the BL and the brightness of the glow during the observation period are not observed.

There is evidence of observation of the process of the emergence of CMM from electrical outlets or operating electrical appliances. In this case, a luminous point first appears, which within a few seconds increases to a size of about 10 cm. In all such cases, the BL exists for several seconds and is destroyed with a characteristic pop without significant harm to the objects present and surroundings.

How ball lightning is formed

It is formed, as a rule, during a strong thunderstorm, however, it has been noticed more than once in sunny weather. Ball lightning occurs suddenly and in a single case. It can appear from clouds, from trees or other objects and buildings. Ball lightning easily overcomes obstacles in its path, including falling into confined spaces. Cases are described when this type of lightning arose from a TV, aircraft cockpit, sockets, indoors ... At the same time, it can bypass objects in its path, passing through them.

Repeatedly, the occurrence of an electric clot was recorded in the same places. The process of movement or migration of lightning occurs mainly horizontally and at a height of about a meter above the ground. There is also a sound accompaniment in the form of a crunch, crackle and squeak, which leads to interference in the radio.

According to the descriptions of eyewitnesses of this phenomenon, two types of lightning are distinguished:

Characteristics

The origin of such lightning is still unknown. There are versions that an electric discharge occurs either on the surface of lightning, or comes out of the total volume.

Scientists do not yet know the physical and chemical composition, thanks to which such a phenomenon of nature can easily overcome doorways, windows, small gaps, and again acquire its original size and shape. In this regard, hypothetical assumptions were put forward about the structure of gas, but such a gas, according to the laws of physics, would have to fly into the air under the influence of internal heat.

The size of ball lightning is usually 10 - 20 centimeters.
The color of the glow, as a rule, can be blue, white or orange. However, witnesses of this phenomenon report that a permanent color was not observed and it always changed.
The shape of ball lightning is in most cases spherical.
The duration of existence was estimated to be no more than 30 seconds.
The temperature has not been fully investigated, but according to experts, it is up to 1000 degrees Celsius.

Without knowing the nature of the origin of this natural phenomenon, it is difficult to make assumptions about how ball lightning moves. According to one theory, the movement of this form of electric discharge can occur due to the force of the wind, the action of electromagnetic oscillations, or the force of attraction.

Why ball lightning is dangerous

Despite the many different hypotheses about the nature of the occurrence and characteristics of this natural phenomenon, it must be taken into account that interaction with ball lightning is extremely dangerous, since a ball filled with a large discharge can not only injure, but also kill. An explosion can lead to tragic consequences.

The first rule to follow when meeting with a fireball is not to panic, do not run, do not make quick and abrupt movements.
It is necessary to slowly leave the trajectory of the ball, while keeping a distance from it and not turn your back.
When ball lightning appears in a closed room, the first thing to do is to try to carefully open the window in order to create a draft.
In addition to the above rules, it is strictly forbidden to throw any objects into the plasma ball, as this can lead to a fatal explosion.

So in the Lugansk region, lightning the size of a golf ball killed a driver, and in Pyatigorsk, a man, trying to brush off a luminous ball, received severe burns on his hands. In Buryatia, lightning descended through the roof and exploded in the house. The explosion was so strong that the windows and doors were knocked out, the walls were damaged, and the owners of the household were injured and received a shell shock.