The origin of lightning. What is lightning? How is this natural phenomenon formed and where does it come from?

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Thunder and lightning

Thunder is a sound phenomenon in the atmosphere that accompanies a lightning strike. Thunder is air fluctuations under the influence of a very rapid increase in pressure along the path of lightning, due to heating up to about 30,000 ° C. Thunder rolls occur due to the fact that lightning has a significant length and sound from different parts of it and does not reach the observer's ear at the same time, in addition, the reflection of sound from clouds contributes to the occurrence of rolls, and also because, due to refraction, the sound wave propagates along different ways and comes with different delays, in addition, the discharge itself does not occur instantly, but continues for a finite time.

The volume of thunderclaps can be up to 120 decibels.

By measuring the time elapsed between a flash of lightning and a thunderclap, you can approximately determine the distance at which a thunderstorm is located. Since the speed of light is very high compared to the speed of sound, it can be neglected, considering only the speed of sound, which is approximately 350 meters per second. (But the speed of sound is very changeable, it depends on the air temperature, the lower it is, the lower the speed.) judge whether the thunderstorm is approaching the observer (the interval between lightning and thunder is reduced) or receding (the interval is increased). As a rule, thunder is heard at a distance of up to 15-20 kilometers, so if an observer sees lightning, but does not hear thunder, then the thunderstorm is at a distance of at least 20 kilometers.

Spark discharge (electric spark)- non-stationary form of electric discharge occurring in gases. Such a discharge usually occurs at pressures of the order of atmospheric and is accompanied by a characteristic sound effect - the "crackle" of a spark. The temperature in the main channel of the spark discharge can reach 10,000 K. In nature, spark discharges often occur in the form of lightning. The distance "pierced" by a spark in air depends on the voltage and is considered equal to 10 kV per centimeter.

A spark discharge usually occurs when the power source is insufficient to sustain a steady state arc or glow discharge. In this case, simultaneously with a sharp increase in the discharge current, the voltage across the discharge gap for a very short time (from several microseconds to several hundred microseconds) falls below the extinction voltage of the spark discharge, which leads to the termination of the discharge. Then the potential difference between the electrodes increases again, reaches the ignition voltage and the process repeats. In other cases, when the power of the energy source is large enough, the entire set of phenomena characteristic of this discharge is also observed, but they are only a transient process leading to the establishment of a discharge of another type - most often an arc one. If the current source is not capable of sustaining a self-sustained electric discharge for a long time, then a form of self-discharge is observed, called a spark discharge.

A spark discharge is a bunch of bright, rapidly disappearing or replacing each other filamentary, often highly branched stripes - spark channels. These channels are filled with plasma, which, in a powerful spark discharge, includes not only the ions of the initial gas, but also the ions of the substance of the electrodes, which are intensively evaporated under the action of the discharge. The mechanism for the formation of spark channels (and, consequently, the occurrence of a spark discharge) is explained by the streamer theory of electrical breakdown of gases. According to this theory, streamers are formed from electron avalanches arising in the electric field of the discharge gap under certain conditions - dimly glowing thin branched channels that contain ionized gas atoms and free electrons split off from them. Among them are the so-called. the leader is a weakly luminous discharge, “paving the way” for the main discharge. Moving from one electrode to another, it closes the discharge gap and connects the electrodes with a continuous conducting channel. Then, in the opposite direction along the paved path, the main discharge passes, accompanied by a sharp increase in the current strength and the amount of energy released in them. Each channel rapidly expands, resulting in a shock wave at its boundaries. The aggregate of shock waves from the expanding spark channels generates a sound perceived as a “crackle” of a spark (in the case of lightning, thunder).

The spark ignition voltage is usually quite high. The electric field strength in the spark decreases from several tens of kilovolts per centimeter (kv / cm) at the moment of breakdown to ~ 100 volts per centimeter (v / cm) after a few microseconds. The maximum current in a powerful spark discharge can reach values ​​of the order of several hundred thousand amperes.

A special type of spark discharge is a sliding spark discharge that occurs along the interface between a gas and a solid dielectric placed between the electrodes, provided that the field strength exceeds the breakdown strength of air. Areas of a sliding spark discharge, in which charges of any one sign prevail, induce charges of a different sign on the surface of the dielectric, as a result of which the spark channels spread over the surface of the dielectric, thus forming the so-called Lichtenberg figures. Processes similar to those occurring during a spark discharge are also characteristic of a brush discharge, which is a transitional stage between corona and spark.

Lightning- a giant electric spark discharge in the atmosphere, usually occurs during a thunderstorm, manifested by a bright flash of light and an accompanying thunder. Lightning has also been recorded on Venus, Jupiter, Saturn and Uranus. The current in a lightning discharge reaches 10-20 thousand amperes, so few people manage to survive after being struck by lightning.

The electrical nature of lightning was revealed in the studies of the American physicist B. Franklin, on whose idea an experiment was carried out to extract electricity from a thundercloud. Franklin's experience in elucidating the electrical nature of lightning is widely known. In 1750 he published a work describing an experiment using a kite launched in a thunderstorm. Franklin's experience was described in the work of Joseph Priestley.

The average length of lightning is 2.5 km; some discharges extend in the atmosphere for a distance of up to 20 km. The current in a lightning discharge reaches 10-20 thousand amperes.

Lightning formation

Most often, lightning occurs in cumulonimbus clouds, then they are called thunderclouds; sometimes lightning is formed in stratus clouds, as well as during volcanic eruptions, tornadoes and dust storms.

Linear lightnings are usually observed, which are referred to as electrodeless discharges, since they begin (and end) in clusters of charged particles. This determines some of their still unexplained properties that distinguish lightning from discharges between electrodes. So, lightning is never shorter than a few hundred meters; they arise in electric fields that are much weaker than fields during interelectrode discharges; the collection of charges carried by lightning occurs in thousandths of a second from billions of small, well-isolated particles located in a volume of several km³. The most studied process of lightning development in thunderclouds, while lightning can pass in the clouds themselves - intracloud lightning, and can strike the ground - ground lightning. For lightning to occur, it is necessary that in a relatively small (but not less than a certain critical) volume of the cloud an electric field (see atmospheric electricity) with an intensity sufficient for the onset of an electric discharge (~ 1 MV / m) to exist, and in a significant part of the cloud there would be a field with an average intensity sufficient to maintain the incipient discharge (~ 0.1-0.2 MV / m). In lightning, the electrical energy of the cloud is converted into heat and light.

Ground lightning

The development process of ground lightning consists of several stages. At the first stage, in the zone where the electric field reaches a critical value, impact ionization begins, initially created by free charges, which are always present in small quantities in the air, which, under the action of an electric field, acquire significant velocities towards the ground and, colliding with the molecules that make up air, ionize them. According to more modern concepts, the discharge is initiated by high-energy cosmic rays, which trigger a process called runaway breakdown. Thus, electronic avalanches appear, transforming into filaments of electrical discharges - streamers, which are well-conducting channels, which, merging, give rise to a bright thermo-ionized channel with high conductivity - a stepped lightning leader.

The leader moves to the earth's surface in steps of several tens of meters at a speed of ~ 50,000 kilometers per second, after which its movement stops for several tens of microseconds, and the glow weakens greatly; then, in the next stage, the leader again moves several tens of meters. At the same time, a bright glow covers all the steps passed; then stop and weakening of the glow follow again. These processes are repeated when the leader moves to the surface of the earth at an average speed of 200,000 meters per second.

As the leader moves to the ground, the field strength at its end increases and under its action, a response streamer is thrown out of objects protruding on the Earth's surface, connecting with the leader. This feature of lightning is used to create a lightning rod.

At the final stage, a reverse (from bottom to top) or main lightning discharge follows along the channel ionized by the leader, characterized by currents from tens to hundreds of thousands of amperes, a brightness significantly exceeding the leader's brightness, and a high speed of advancement, initially reaching ~ 100,000 kilometers per second , and at the end it decreases to ~ 10,000 kilometers per second. The channel temperature during the main discharge can exceed 25,000 ° C. The length of the lightning channel can be from 1 to 10 km, the diameter is several centimeters. After the passage of the current pulse, the ionization of the channel and its luminescence become weaker. In the final stage, the lightning current can last for hundredths and even tenths of a second, reaching hundreds and thousands of amperes. Such lightning strikes are called lingering, they most often cause fires.

Many people are afraid of a terrible natural phenomenon - thunderstorms. This usually happens when the sun is covered with dark clouds, there is a terrible thunder and it is raining heavily.

Of course, one should be afraid of lightning, because it can even kill or become.This has been known for a long time, therefore, various means of protection against lightning and thunder have been invented (for example, metal poles).

What is happening up there and where does the thunder come from? And how does lightning arise?

Thunderclouds

Usually huge. They reach several kilometers in height. Visually, you cannot see how everything boils and boils inside these explosive clouds. This air, including water droplets, moves at high speed from bottom to top and vice versa.

The uppermost part of these clouds in terms of temperature reaches -40 degrees, and water droplets falling into this part of the cloud freeze.

About the origin of thunderclouds

Before we know where thunder and lightning come from, how it arises, let's briefly describe how thunderclouds are formed.

Most of these phenomena occur not over the water surface of the planet, but over the continents. In addition, thunderstorm clouds form intensively over the continents of tropical latitudes, where the air near the earth's surface (in contrast to the air above the water surface) warms up strongly and rises rapidly upward.

Usually, on the slopes of different heights, a similar heated air is formed, which draws in moist air from vast areas of the earth's surface and raises it up.

Thus, the so-called cumulus clouds are formed, turning into thunderclouds, described just above.

Now let's clarify what lightning is, where does it come from?

Lightning and thunder

From those very frozen droplets, pieces of ice are formed, which also move in the clouds at a tremendous speed, colliding, collapsing and being charged with electricity. Those pieces of ice that are lighter and smaller remain at the top, and those that are larger - melt, going down, again turning into water droplets.

Thus, two electric charges arise in a thundercloud. Negative at the top, positive at the bottom. When different charges meet, a powerful one arises and lightning occurs. Where it comes from, it became clear. What happens next? A flash of lightning instantly heats up and expands the air around it. The latter heats up so much that an explosion effect occurs. This is the thunder that frightens all life on earth.

It turns out that all these are manifestations. Then the next question arises as to where the latter comes from, and in such large quantities. And where does it go?

Ionosphere

What is lightning, where does it come from, they figured out. Now a little about the processes that conserve the Earth's charge.

Scientists have found that the Earth's charge is generally small and is only 500,000 coulombs (like 2 car batteries). Then where does the negative charge that is carried by lightning closer to the Earth's surface disappear?

Usually, in clear weather, the Earth is slowly discharged (a weak current constantly passes between the ionosphere and the Earth's surface through the entire atmosphere). Although air is considered an insulator, it contains a small fraction of ions, which allows current to exist in the volume of the entire atmosphere. Due to this, albeit slowly, but the negative charge is transferred from the earth's surface to the height. Therefore, the volume of the total charge of the Earth always remains unchanged.

Today, the most widespread opinion is that ball lightning is a special kind of ball-shaped charge, which has existed for quite a long time and moves along an unpredictable trajectory.

Today there is no unified theory of the occurrence of this phenomenon. There are many hypotheses, but so far none have received recognition among scientists.

Usually, as eyewitnesses testify, it occurs in a thunderstorm or in a storm. But there are also cases of its occurrence in sunny weather. More often it is generated by ordinary lightning, sometimes it appears and descends from the clouds, and less often it appears unexpectedly in the air or even can come out of some object (pillar, tree).

Some interesting facts

Where do thunderstorms and lightning come from, we found out. Now a little about the curious facts regarding the above-described natural phenomena.

1. Every year the Earth experiences approximately 25 million lightning flashes.

2. Lightning has an average length of approximately 2.5 km. There are also discharges extending 20 km in the atmosphere.

3. There is a belief that lightning cannot strike twice in one place. In reality, this is not the case. The results of the analysis (on a geographical map) of the places of lightning strikes over the previous several years show that lightning can strike the same place several times.

So we found out what lightning is, where it comes from.

Thunderstorms are formed as a consequence of the most complex atmospheric phenomena of a planetary scale.

About 50 lightning flashes occur on planet Earth every second.

The clouds spread their wings and closed the sun from us ...

Why do we sometimes hear thunder and see lightning during the rain? Where do these outbreaks come from? Now we will tell you about this in detail.

What is lightning?

What is lightning? This is an amazing and very mysterious natural phenomenon. It almost always happens during a thunderstorm. Someone is amazed, someone is frightened. Poets write about lightning, scientists study this phenomenon. But much remained unsolved.

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

And there are also lightnings on other planets. For example, on Mars or Venus. Normal lightning lasts only a split second. At the same time, it consists of several categories. Lightning appears sometimes quite unexpectedly.

How does lightning form?

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

What are the types of lightning?

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! So far, we will name only the most basic ones, attaching pictures of lightning to them:

• Between a thundercloud and the ground. These are the same "ribbons" to which we are accustomed.

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

Ribbon zipper - when not one "ribbon", but several in parallel.

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

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

• And everyone has heard about ball lightning! Few only who saw them. There are even fewer people who would like to see them. And there are also people who do not believe in their existence. But fireballs do exist! It is difficult to photograph such lightning. It explodes quickly, although it can "walk", but a person next to it is better not to move - it is dangerous. So it's not up to the camera here.

• A type of lightning with a very beautiful name - "St. Elmo's Lights". But this is not really lightning. This is the glow that appears at the end of a thunderstorm on gabled buildings, lanterns, ship masts. Also a spark, only not fading and not dangerous. The lights of Saint Elmo are very beautiful.

• Volcanic lightning occurs during a volcanic eruption. The volcano itself already has a charge. This is probably the cause of the lightning.

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

• Dotted lightning has hardly been studied. It is extremely rare to observe it. Visually, it really looks like a dotted line - as if a lightning ribbon is melting.

These are the different lightning bolts. There is only one law for them - 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 is always insanely beautiful!

Typically seen after lightning. Such phenomena caused a terrible feeling of fear in our ancestors, they considered them a manifestation of the anger of the gods. During the time of the ancient Slavs, paganism was widespread. They worshiped various gods, including Perun - the god of thunder, lightning and thunder. He was the main one in the ancient Slavic pantheon. And, like any great, a personal holiday was dedicated. Perun Day was celebrated on July 21. God was revered as giving life-giving rain to nature. On this day, the ancestors glorified him, after they consecrated their weapons, made a sacrifice, carried out a ceremony of commemoration of the soldiers who fell in battle. The day ended with a plentiful meal and games.

These times have sunk into oblivion, but thunder and lightning remain. Let's take a look at specialized reference books or natural history textbooks. There we can read what thunder is - this is the sound of vibrating air around lightning, which quickly heats up and expands. You have probably noticed more than once that sometimes we first see an electric discharge, and only then we hear a roar. This happens because light waves travel at a speed of about 300,000 km / s, and sound waves travel much slower, about 335 m / s. But thunder and lightning are not always the same during a thunderstorm. It so happens that a flash of lightning has occurred, but no sounds are heard. This can happen if the thunderstorm is quite far away. It happens that thunder rumbles, but the lightning is not visible - it will be difficult to see it on a clear day and when it forms inside a cloud.

If you want to know how far away a thunderstorm is, it's easy to do. You just need to calculate how many seconds will pass between the flash of an electric discharge and the sound of thunder, divide by three, and you will know how many kilometers a thunderstorm is coming from you. If you make several such calculations, then you can find out if a cloud is approaching or moving away from you. In the case when the thunder is not heard, it can be argued that the thunderstorm front is more than twenty kilometers from you.

To understand how lightning is formed, you should remember the school curriculum - the section on electricity. It is known that all objects are charged either positively or negatively. During a thunderstorm in a cloud, droplets condense and pick up positively charged particles. The cloud becomes negatively charged with respect to the Earth. When the charge in the rain cloud is too large, a lightning discharge occurs. You can observe the same phenomenon when such a thing occurs between the clouds.

Now let's figure out what is thunder? During an electric discharge, air expands very quickly, then contracts, while there is a rapid movement of air currents. When there is a contact between them, the sound of thunder is heard. The volume of these rumblings can reach 120 decibels.

After reading this article, you have learned for yourself and will be able to explain to little people what thunder and lightning are, how they are formed and why there is a roar.

Linear lightning is usually accompanied by a strong, rolling sound called thunder. Thunder occurs for the following reason. We have seen that the current in the lightning channel is generated within a very short period of time. At the same time, the air in the channel heats up very quickly and strongly, and it expands from heating. The expansion is so fast that it looks like an explosion. This explosion produces a concussion of the air, which is accompanied by strong sounds. After a sudden cessation of the current, the temperature in the lightning channel quickly drops, as the heat escapes into the atmosphere. The channel cools quickly and the air in it is therefore sharply compressed. It also causes a concussion in the air, which again produces sound. It is understood that repeated lightning strikes can cause continuous rumble and noise. In turn, the sound is reflected from clouds, earth, houses and other objects and, creating multiple echoes, lengthens the thunder. Therefore, there are thunderclaps.

Like any sound, thunder travels through the air at a relatively low speed - about 330 meters per second. This speed is only one and a half times the speed of a modern aircraft. If the observer first sees lightning and only after a while hears thunder, then he can determine the distance that separates him from the lightning. For example, let it take 5 seconds between lightning and thunder. Since for each second the sound runs 330 meters, then in five seconds the thunder covered a distance five times greater, namely 1650 meters. This means that the lightning struck less than two kilometers from the observer.

In calm weather, thunder is heard in 70-90 seconds, passing 25-30 kilometers. Thunderstorms that pass from the observer at a distance of less than three kilometers are considered close, and thunderstorms passing at a greater distance are considered distant.

In addition to linear, there are, however much less often, other types of lightning. Of these, we will consider one, the most interesting - ball lightning.

Sometimes lightning discharges are observed, which are fireballs. How ball lightning is formed has not yet been studied, but the available observations of this interesting type of lightning discharge allow us to draw some conclusions. Here is one of the most interesting descriptions of ball lightning.

Here is what the famous French scientist Flammarion reports: “On June 7, 1886, at half past seven in the evening, during a thunderstorm that broke out over the French city of Gray, the sky suddenly lit up with a wide red lightning, and with a terrible crash a fireball fell from the sky, apparently , 30-40 centimeters. Scattering sparks, he hit the end of the ridge of the roof, knocked off a piece more than half a meter long from its main beam, split it into small pieces, covered the attic with debris and brought down plaster from the ceiling of the upper floor. Then this ball jumped to the roof of the entrance, punched a hole in it, fell onto the street and, having rolled along it for some distance, gradually disappeared. Fire balloon

It didn’t do anything and didn’t harm anyone, despite the fact that there were a lot of people on the street ”.

In fig. 13 shows a ball lightning captured by a photographic apparatus, and Fig. 14 depicts a painting by an artist who painted a ball of lightning that fell into the courtyard.

Most often, ball lightning is in the shape of a watermelon or pear. It lasts for a relatively long time - from a small fraction of Fig. 13. Ball lightning. seconds to several minutes.

The most common duration for ball lightning is 3 to 5 seconds. Ball lightning most often appears at the end of a thunderstorm in the form of red glowing balls with a diameter of 10 to 20 centimeters. In more rare cases, it also has large times - 22

Measures. For example, lightning with a diameter of about 10 meters was photographed.

The ball can sometimes be dazzling white and have a very sharp outline. Ball lightning usually makes a hissing, buzzing or hissing sound.

Ball lightning can fade silently, but it can emit a faint crackle or even deafening sound.

Explosion. When it disappears, it often leaves a pungent-smelling haze. Near the ground or in closed rooms, ball lightning moves at the speed of a running person - approximately two meters per second. It can remain at rest for some time, and such a "settled" ball hisses and throws out sparks until it disappears. Sometimes it seems that ball lightning is driven by the wind, but usually its movement does not depend on the wind.

Ball lightning is attracted to closed rooms, into which they penetrate through open windows or doors, and sometimes even through small crevices. The pipes are a good way for them; therefore, fireballs often emerge from ovens in kitchens. Having circled around the room, ball lightning leaves the room, often leaving along the very path along which it entered.

Sometimes lightning rises and falls two or three times at distances from several centimeters to several

Kikh meters. Simultaneously with these ups and downs, the fireball sometimes moves in a horizontal direction, and then it seems that the ball lightning is making jumps.

Often, fireballs "settle" on conductors, preferring the highest points, or roll along conductors, for example, along drainpipes. Moving over the bodies of people, sometimes under clothes, fireballs cause severe burns and even death. There are many descriptions of cases of fatal damage to humans and animals by ball lightning. Ball lightning can cause very severe damage to buildings.

There is no complete scientific explanation for ball lightning yet. Scientists have stubbornly studied ball lightning, but so far all its various manifestations have not been explained. There is still a lot of scientific work to be done in this area. Of course, there is nothing mysterious, "supernatural" in ball lightning. This is an electrical discharge, the origin of which is the same. as with linear lightning. Undoubtedly, in the near future, scientists will be able to explain all the details of ball lightning as well as they were able to explain all the details of linear lightning,