How a thunderstorm is formed. Thunder and lightning About thunderstorms in ancient mythology

Lightning is a powerful electrical discharge. It occurs when clouds or ground are highly electrified. Therefore, lightning discharges can occur either inside a cloud, or between neighboring electrified clouds, or between an electrified cloud and the ground. A lightning discharge is preceded by the occurrence of an electrical potential difference between neighboring clouds or between a cloud and the ground.

Electrification, that is, the formation of attractive forces electrical nature, is well known to everyone from everyday experience.

What causes clouds to electrify? After all, they do not rub against each other, as happens when an electrostatic charge forms on the hair and on the comb.

A thundercloud is a huge amount of steam, some of which is condensed in the form of tiny droplets or floes of ice. The top of a thundercloud can be at an altitude of 6-7 km, and the bottom can hang above the ground at an altitude of 0.5-1 km. Above 3-4 km the clouds consist of ice floes different sizes, since the temperature there is always below zero. These pieces of ice are in constant motion caused by rising currents warm air from the heated surface of the earth. Small pieces of ice are more easily carried away by rising air currents than large ones. Therefore, “nimble” small pieces of ice, moving to the top of the cloud, constantly collide with large ones. Each such collision leads to electrification. In this case, large pieces of ice are charged negatively, and small ones - positively. Over time, positively charged small pieces of ice end up at the top of the cloud, and negatively charged large ones end up at the bottom. In other words, the top of a thundercloud is positively charged and the bottom is negatively charged.

The electric field of a cloud has a huge intensity - about a million V/m. When large, oppositely charged regions come close enough to each other, some electrons and ions, running between them, create a glowing plasma channel through which other charged particles rush after them. This is how a lightning discharge occurs.

During this discharge, enormous energy is released - up to a billion J. The temperature of the channel reaches 10,000 K, which gives rise to the bright light that we observe during a lightning discharge. Clouds are constantly discharged through these channels, and we see external manifestations of the data atmospheric phenomena in the form of lightning.

The hot medium expands explosively and causes a shock wave, perceived as thunder.

We ourselves can simulate lightning, even a miniature one. The experiment should be carried out in a dark room, otherwise nothing will be visible. We will need two oblong balloons. Let's inflate them and tie them. Then, making sure that they do not touch, we simultaneously rub them with a woolen cloth. The air filling them is electrified. If the balls are brought closer together, leaving a minimum gap between them, sparks will begin to jump from one to the other through a thin layer of air, creating light flashes. At the same time, we will hear a faint crackling sound - a miniature copy of thunder during a thunderstorm.

Everyone who has seen lightning has noticed that it is not a brightly glowing straight line, but a broken line. Therefore, the process of forming a conductive channel for a lightning discharge is called its “step leader”. Each of these “steps” is a place where electrons, accelerated to near-light speeds, stopped due to collisions with air molecules and changed the direction of movement.

Thus, lightning is a breakdown of a capacitor whose dielectric is air, and the plates are clouds and earth. The capacity of such a capacitor is small - approximately 0.15 μF, but the energy reserve is enormous, since the voltage reaches a billion volts.

One lightning usually consists of several discharges, each of which lasts only a few tens of millionths of a second.

Lightning most often occurs in cumulonimbus clouds. Lightning also occurs during volcanic eruptions, tornadoes and dust storms.

There are several types of lightning in shape and direction of discharge. Discharges can occur:

• between a thundercloud and the ground,
• between two clouds
• inside the cloud,
• leaving the clouds for clear skies.

Ancient people did not always consider thunderstorms and lightning, as well as the accompanying clap of thunder, to be a manifestation of the wrath of the gods. For example, for the Hellenes, thunder and lightning were symbols of supreme power, while the Etruscans considered them signs: if a flash of lightning was seen from the east, it meant that everything would be fine, and if it flashed in the west or northwest, it meant the opposite.

The Etruscan idea was adopted by the Romans, who were convinced that a lightning strike from the right side was sufficient reason to postpone all plans for a day. The Japanese had an interesting interpretation of heavenly sparks. Two vajras (lightning bolts) were considered symbols of Aizen-meo, the god of compassion: one spark was on the deity’s head, the other he held in his hands, suppressing all the negative desires of humanity with it.

Lightning is huge size an electrical discharge, which is always accompanied by a flash and thunderclaps (a shining discharge channel resembling a tree is clearly visible in the atmosphere). At the same time, there is almost never just one flash of lightning; it is usually followed by two or three, often reaching several dozen sparks.

These discharges almost always form in cumulonimbus clouds, sometimes in nimbostratus clouds large sizes: the upper boundary often reaches seven kilometers above the surface of the planet, while the lower part can almost touch the ground, staying no higher than five hundred meters. Lightning can form both in one cloud and between nearby electrified clouds, as well as between a cloud and the ground.

A thundercloud consists of large quantity steam condensed in the form of ice floes (at an altitude exceeding three kilometers these are almost always ice crystals, since temperatures here do not rise above zero). Before a cloud becomes a thunderstorm, ice crystals begin to actively move inside it, and they are helped to move by rising currents of warm air from the heated surface.

Air masses carry upward smaller pieces of ice, which during movement constantly collide with larger crystals. As a result, smaller crystals become positively charged, while larger ones become negatively charged.

After small ice crystals collect at the top and large ones at the bottom, top part The cloud turns out to be positively charged, the lower one – negatively. Thus, the electric field strength in the cloud reaches extremely high performance: million volts per meter.

When these oppositely charged areas collide with each other, ions and electrons at the points of contact form a channel through which all charged elements rush down and an electrical discharge is formed - lightning. At this time it stands out so much powerful energy, that its power would be enough to power a 100 W light bulb for 90 days.

The channel heats up to almost 30 thousand degrees Celsius, which is five times higher than the temperature of the Sun, producing a bright light (the flash usually lasts only three quarters of a second). After the channel is formed, the thundercloud begins to discharge: the first discharge is followed by two, three, four or more sparks.

A lightning strike resembles an explosion and causes the formation of a shock wave, which is extremely dangerous for any living creature near the canal. A shock wave of a strong electrical discharge a few meters away is quite capable of breaking trees, injuring or concussing even without direct electric shock:

• At a distance of up to 0.5 m from the channel, lightning can destroy weak structures and injure a person;
• At a distance of up to 5 meters, buildings remain intact, but can break windows and stun a person;
• At long distances the shock wave negative consequences does not carry and turns into a sound wave known as thunderclaps.

Rolling thunder

A few seconds after a lightning strike was recorded, due to a sharp increase in pressure along the channel, the atmosphere heats up to 30 thousand degrees Celsius. As a result, explosive vibrations of the air occur and thunder occurs. Thunder and lightning are closely interrelated with each other: the length of the discharge is often about eight kilometers, so the sound from different parts of it reaches the different time, forming thunderclaps.

Interestingly, by measuring the time that passes between thunder and lightning, you can find out how far the epicenter of the thunderstorm is from the observer.

To do this, you need to multiply the time between lightning and thunder by the speed of sound, which is from 300 to 360 m/s (for example, if the time interval is two seconds, the epicenter of the thunderstorm is a little more than 600 meters from the observer, and if three - at a distance kilometer). This will help determine whether a storm is moving away or approaching.

Amazing fireball

One of the least studied, and therefore most mysterious, natural phenomena is considered ball lightning- a glowing plasma ball moving through the air. It is mysterious because the principle of the formation of ball lightning is unknown to this day: despite the fact that it exists big number hypotheses explaining the reasons for the appearance of this amazing phenomenon nature, there were objections to each of them. Scientists have never been able to experimentally achieve the formation of ball lightning.

Ball lightning can exist for a long time and move along an unpredictable trajectory. For example, it is quite capable of hovering in the air for several seconds and then darting to the side.

Unlike a simple discharge, there is always only one plasma ball: until two or more fiery lightning bolts are detected simultaneously. The dimensions of ball lightning range from 10 to 20 cm. Ball lightning is characterized by white, orange or blue tones, although other colors, even black, are often found.

Scientists have not yet determined the temperature indicators of ball lightning: despite the fact that, according to their calculations, it should range from one hundred to a thousand degrees Celsius, people who were close to this phenomenon did not feel the heat emanating from the ball lightning.

The main difficulty in studying this phenomenon is that scientists are rarely able to record its occurrence, and eyewitness testimony often casts doubt on the fact that the phenomenon they observed was indeed ball lightning. First of all, testimonies differ regarding the conditions under which she appeared: she was mainly seen during a thunderstorm.

There are also indications that ball lightning can appear on a fine day: it can descend from the clouds, appear in the air, or appear from behind an object (a tree or a pole).

One more characteristic feature ball lightning is its penetration into closed rooms, it has even been noticed in pilot cockpits ( fire ball can penetrate windows, go down ventilation ducts, and even fly out of sockets or TVs). Situations have also been repeatedly documented when a plasma ball was fixed in one place and constantly appeared there.

Often the appearance of ball lightning does not cause trouble (it moves calmly in air currents and after some time flies away or disappears). But sad consequences were also noticed when it exploded, instantly evaporating the liquid located nearby, melting glass and metal.

Possible dangers

Since the appearance of ball lightning is always unexpected, when you see this unique phenomenon near you, the main thing is not to panic, not to move abruptly and not to run anywhere: fire lightning is very susceptible to air vibrations. It is necessary to quietly leave the trajectory of the ball and try to stay as far away from it as possible. If a person is indoors, you need to slowly walk to the window opening and open the window: there are many stories when a dangerous ball left the apartment.

You cannot throw anything into a plasma ball: it is quite capable of exploding, and this is fraught not only with burns or loss of consciousness, but also with cardiac arrest. If it happens that the electric ball catches a person, you need to move him to a ventilated room, wrap him warmly, perform a heart massage, perform artificial respiration and immediately call a doctor.

What to do in a thunderstorm

When a thunderstorm begins and you see lightning approaching, you need to find shelter and hide from the weather: a lightning strike is often fatal, and if people survive, they often remain disabled.

If there are no buildings nearby, and a person is in the field at that time, he must take into account that it is better to hide from a thunderstorm in a cave. And here tall trees it is advisable to avoid: lightning usually hits the largest plant, and if the trees are the same height, it hits the one that conducts electricity better.

To protect a free-standing building or structure from lightning, a high mast is usually installed near it, at the top of which there is a pointed metal rod securely connected to a thick wire; at the other end there is a metal object buried deep in the ground. The operation scheme is simple: the rod from a thundercloud is always charged with a charge opposite to the cloud, which, flowing down the wire underground, neutralizes the charge of the cloud. This device is called a lightning rod and is installed on all buildings in cities and other human settlements.

Here's what was recently clean, clear sky clouds covered. The first drops of rain fell. And soon the elements demonstrated their power to the earth. Thunder and lightning pierced the stormy sky. Where do such phenomena come from? For many centuries, humanity has seen in them a manifestation of divine power. Today we know about the occurrence of such phenomena.

Origin of thunderclouds

Clouds appear in the sky from condensation rising high above the ground and float in the sky. The clouds are heavier and larger. They bring with them all the “special effects” that come with bad weather.

Thunderclouds differ from ordinary clouds in that they are charged with electricity. Moreover, there are clouds with a positive charge, and there are clouds with a negative one.

To understand where thunder and lightning come from, you need to rise higher above the ground. In the sky, where there are no obstacles to free flight, the winds blow stronger than on the ground. They are the ones who provoke the charge in the clouds.

The origin of thunder and lightning can be explained by just one drop of water. It has a positive charge of electricity in the center and a negative charge on the outside. The wind breaks it into pieces. One of them remains with a negative charge and has less weight. Heavier positively charged drops form the same clouds.

Rain and electricity

Before thunder and lightning appear in a stormy sky, the wind separates the clouds into positively and negatively charged ones. Rain falling on the ground takes some of this electricity with it. An attraction forms between the cloud and the surface of the earth.

The negative charge of the cloud will attract the positive one on the ground. This attraction will be located evenly on all surfaces that are elevated and conduct current.

And now the rain creates all the conditions for the appearance of thunder and lightning. The higher the object is to the cloud, the easier it is for lightning to break through to it.

Origin of lightning

The weather has prepared all the conditions that will help all its effects appear. She created the clouds from which thunder and lightning come.

A roof charged with negative electricity attracts the positive charge of the most exalted object. Its negative electricity will go into the ground.

Both of these opposites tend to attract each other. The more electricity there is in a cloud, the more it is in the most elevated object.

Accumulating in a cloud, electricity can break through the layer of air located between it and the object, and sparkling lightning will appear and thunder will thunder.

How lightning develops

When a thunderstorm rages, lightning and thunder accompany it incessantly. Most often, the spark comes from a negatively charged cloud. It develops gradually.

First, a small stream of electrons flows from the cloud through a channel directed toward the ground. In this place of the cloud, electrons moving with high speed. Due to this, electrons collide with air atoms and break them up. Individual nuclei are obtained, as well as electrons. The latter also rush to the ground. While they move along the channel, all primary and secondary electrons again split the air atoms standing in their way into nuclei and electrons.

The whole process is like an avalanche. It is moving upward. The air heats up and its conductivity increases.

More and more electricity from the cloud flows to the ground at a speed of 100 km/s. At this moment, lightning makes its way to the ground. Along this road laid by the leader, electricity begins to flow even faster. A discharge of enormous force occurs. Reaching its peak, the discharge decreases. The channel, heated by such a powerful current, glows. And lightning becomes visible in the sky. Such a discharge does not last long.

After the first discharge, a second one often follows along a laid channel.

How does thunder appear?

Thunder, lightning, and rain are inseparable during a thunderstorm.

Thunder occurs for the following reason. The current in the lightning channel is generated very quickly. The air becomes very hot. This makes it expand.

It happens so quickly that it resembles an explosion. Such a shock shakes the air violently. These vibrations lead to the appearance of a loud sound. This is where lightning and thunder come from.

As soon as the electricity from the cloud reaches the ground and disappears from the channel, it cools very quickly. Compressing air also causes thunder to sound.

The more lightning that passes through the channel (there can be up to 50 of them), the longer the air tremors. This sound is reflected from objects and clouds, and an echo occurs.

Why is there an interval between lightning and thunder?

In a thunderstorm, lightning is followed by thunder. Its delay from lightning occurs due to the different speeds of their movement. Sound moves at a relatively low speed (330 m/s). This is only 1.5 times faster than the movement of a modern Boeing. The speed of light is much greater than the speed of sound.

Thanks to this interval, it is possible to determine how far flashing lightning and thunder are from the observer.

For example, if 5 s passed between lightning and thunder, this means that the sound traveled 330 m 5 times. By multiplying, it is easy to calculate that the lightning from the observer was at a distance of 1650 m. If a thunderstorm passes closer than 3 km from a person, it is considered close. If the distance, in accordance with the appearance of lightning and thunder, is further, then the thunderstorm is distant.

Lightning in numbers

Thunder and lightning have been modified by scientists, and the results of their research are presented to the public.

It has been found that the potential difference preceding lightning reaches billions of volts. The current strength at the moment of discharge reaches 100 thousand A.

The temperature in the channel heats up to 30 thousand degrees and exceeds the temperature on the surface of the Sun. From the clouds to the ground, lightning travels at a speed of 1000 km/s (in 0.002 s).

The internal channel through which the current flows does not exceed 1 cm, although the visible one reaches 1 m.

There are about 1,800 thunderstorms occurring continuously around the world. The chance of being killed by lightning is 1:2000000 (the same as dying from falling out of bed). The chance of seeing ball lightning is 1 in 10,000.

Ball lightning

On the way to studying where thunder and lightning come from in nature, the most mysterious phenomenon ball lightning appears. These round fiery discharges have not yet been fully studied.

Most often, the shape of such lightning resembles a pear or watermelon. It lasts up to several minutes. Appears at the end of a thunderstorm in the form of red clumps from 10 to 20 cm in diameter. The largest ball lightning ever photographed was about 10 m in diameter. It makes a buzzing, hissing sound.

It may disappear quietly or with a slight crash, leaving a burning smell and smoke.

The movement of lightning does not depend on the wind. They are drawn to closed premises through windows, doors and even cracks. If they come into contact with a person, they leave severe burns and can be fatal.

Until now, the reasons for the appearance of ball lightning were unknown. However, this is not evidence of its mystical origin. Research is being conducted in this area that can explain the essence of this phenomenon.

By becoming familiar with phenomena such as thunder and lightning, you can understand the mechanism of their occurrence. This is a consistent and rather complex physical and chemical process. It represents one of the most interesting phenomena nature, which is found everywhere and therefore affects almost every person on the planet. Scientists have solved the mysteries of almost all types of lightning and even measured them. Ball lightning today is the only unsolved mystery of nature in the field of formation of such natural phenomena.

Report

Thunder and lightning

Thunder is a sound phenomenon in the atmosphere that accompanies a lightning strike. Thunder is the vibration of air under the influence of very rapid promotion pressure along the lightning path due to heating to approximately 30,000 °C. Thunderclaps occur due to the fact that lightning has a significant length and sound from its different parts 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 thunderclaps, and also because due to refraction sound wave spreads along different paths and arrives with different delays; in addition, the discharge itself does not occur instantly, but lasts a finite time.

The volume of thunder can reach 120 decibels.

By measuring the time interval between a flash of lightning and a clap of thunder, you can approximately determine the distance at which the thunderstorm is located. Since the speed of light is very high compared to the speed of sound, it can be neglected, taking into account only the speed of sound, which is approximately 350 meters per second. (But the speed of sound is very variable, depending on the air temperature; the lower it is, the lower the speed.) Thus, by multiplying the time between a flash of lightning and a clap of thunder in seconds by this value, one can judge the proximity of a thunderstorm, and by comparing similar measurements, one can judge whether a thunderstorm is approaching the observer (the interval between lightning and thunder is decreasing) or moving away (the interval is increasing). Typically, thunder can be 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 least 20 kilometers away.

Spark discharge (electric spark)- a non-stationary form of electrical discharge occurring in gases. Such a discharge usually occurs at pressures on the order of atmospheric pressure and is accompanied by a characteristic sound effect - the “crackling” 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 the air depends on the voltage and is considered equal to 10 kV per 1 centimeter.

A spark discharge usually occurs when the energy source is not powerful enough to support a steady 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) drops 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 sufficiently large, the whole set of phenomena characteristic of this discharge is also observed, but they are only a transition process leading to the establishment of a discharge of another type - most often an arc one. If the current source is not capable of maintaining a self-sustained electrical discharge for a long time, then a form of self-sustained discharge called a spark discharge is observed.

A spark discharge is a bunch of bright, quickly disappearing or replacing each other thread-like, often highly branched stripes - spark channels. These channels are filled with plasma, which in a powerful spark discharge includes not only ions of the source gas, but also ions of the electrode substance, which intensively evaporates 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, from electron avalanches arising in the electric field of the discharge gap, under certain conditions, streamers are formed - dimly glowing thin branched channels that contain ionized gas atoms and free electrons split off from them. Among them we can highlight the so-called. leader - a weakly glowing discharge that “paves” the path for the main discharge. Moving from one electrode to another, it closes the discharge gap and connects the electrodes with a continuous conductive channel. Then in reverse direction The main discharge passes along the laid path, 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 combination of shock waves from the expanding spark channels generates a sound perceived as the “crack” of a spark (in the case of lightning, thunder).

The ignition voltage of a spark discharge 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 one sign predominate, induce charges of a different sign on the surface of the dielectric, as a result of which spark channels spread along the surface of the dielectric, 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 transition stage between corona and spark.

Lightning- a giant electrical spark discharge in the atmosphere, usually occurring during a thunderstorm, manifested by a bright flash of light and 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 research 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 that described an experiment using kite launched into 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 up to 20 km in the atmosphere. The current in a lightning discharge reaches 10-20 thousand amperes.

Lightning Formation

Most often, lightning occurs in cumulonimbus clouds, then they are called thunderstorms; Lightning sometimes forms in nimbostratus clouds, as well as during volcanic eruptions, tornadoes and dust storms.

Usually observed linear zippers, which belong to the so-called electrodeless discharges, since they begin (and end) in accumulations of charged particles. This determines their some still unexplained properties that distinguish lightning from discharges between electrodes. Thus, lightning does not occur shorter than several hundred meters; they arise in electric fields much weaker than the fields during interelectrode discharges; The collection of charges carried by lightning occurs in thousandths of a second from billions of small particles, well isolated from each other, 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, or 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 a strength sufficient to initiate an electrical discharge (~ 1 MV/m) must be formed, and in a significant part of the cloud there would be field with an average strength sufficient to maintain the started discharge (~ 0.1-0.2 MV/m). In the lightning Electric Energy clouds turns 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, created initially by free charges, always present in small quantities in the air, which, under the influence of the electric field, acquire significant speeds towards the ground and, colliding with the molecules that make up air, ionize them. For more modern ideas, the discharge is initiated by high-energy cosmic rays, which trigger a process called runaway breakdown. In this way, electron avalanches arise, turning into threads of electrical discharges - streamers, which are well-conducting channels, which, merging, give rise to a bright thermally ionized channel with high conductivity - a stepped lightning leader.

The movement of the leader towards the earth's surface occurs 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 greatly weakens; then, in the subsequent stage, the leader again advances several tens of meters. A bright glow covers all the steps passed; then a stop and weakening of the glow follows again. These processes are repeated when the leader moves to the surface of the earth from average speed 200,000 meters per second.

As the leader moves toward the ground, the field intensity at its end increases and under its action, a response streamer is ejected from objects protruding on the surface of the Earth, connecting to the leader. This feature of lightning is used to create a lightning rod.

In 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 noticeably exceeding the brightness of the leader, and a high speed of progress, initially reaching ~ 100,000 kilometers per second , and at the end decreasing 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 can be several centimeters. After the passage of the current pulse, the ionization of the channel and its glow weaken. In the final stage, the lightning current can last hundredths and even tenths of a second, reaching hundreds and thousands of amperes. Such lightning is called prolonged lightning and most often causes fires.

The main discharge often discharges only part of the cloud. Charges located on high altitudes, can give rise to a new (arrow-shaped) leader moving continuously at speeds of thousands of kilometers per second. The brightness of its glow is close to the brightness of the stepped leader. When the swept leader reaches the surface of the earth, a second main blow follows, similar to the first. Typically, lightning includes several repeated discharges, but their number can reach several dozen. The duration of multiple lightning can exceed 1 second. The displacement of the channel of multiple lightning by the wind creates the so-called ribbon lightning - a luminous strip.

Intracloud lightning

Intracloud lightning usually includes only leader stages; their length ranges from 1 to 150 km. The share of intracloud lightning increases with displacement towards the equator, varying from 0.5 V temperate latitudes up to 0.9 in the equatorial strip. The passage of lightning is accompanied by changes in electric and magnetic fields and radio emissions, the so-called atmospherics.

The probability of a ground object being struck by lightning increases as its height increases and with an increase in the electrical conductivity of the soil on the surface or at some depth (the action of a lightning rod is based on these factors). If there is an electric field in the cloud that is sufficient to maintain a discharge, but not sufficient to cause it to occur, a long metal cable or an airplane can act as the lightning initiator - especially if it is highly electrically charged. In this way, lightning is sometimes “provoked” in nimbostratus and powerful cumulus clouds.

Lightning in upper atmosphere

In 1989 it was discovered special kind lightning - elves, lightning in the upper atmosphere. In 1995, another type of lightning in the upper atmosphere was discovered - jets.

Elves (English Elves; Emissions of Lightand VeryLow Frequency Perturbations from Electromagnetic PulseSources) are huge but faintly luminous cone flares with a diameter of about 400 km, which appear directly from the top of a thundercloud. The height of the elves can reach 100 km, the duration of the flashes is up to 5 ms (on average 3 ms).

Jets are tube-cones of blue color. The height of the jets can reach 40-70 km (the lower boundary of the ionosphere); jets live relatively longer than elves.

Interaction of lightning with the surface of the earth and objects located on it

“Every second, about 50 lightning strikes the surface of the earth, and on average, every square kilometer is struck by lightning six times a year.”

The most powerful lightning strikes cause the birth of fulgurites.

People and lightning

Lightning is a serious threat to human life. A person or animal being struck by lightning often occurs on open spaces, because electricity follows the shortest thundercloud-to-ground path. Often lightning strikes trees and transformer installations on railway, causing them to ignite. It is impossible to be struck by ordinary linear lightning inside a building, but there is an opinion that so-called ball lightning can penetrate through cracks and open windows. Normal lightning is dangerous for television and radio antennas located on the roofs of high-rise buildings, as well as for network equipment.

The same pathological changes are observed in the body of victims as in case of electric shock. The victim loses consciousness, falls, convulsions may occur, and breathing and heartbeat often stop. It is common to find “current marks” on the body, where electricity enters and exits. In case of death the reason for the cessation of the main vital functions is a sudden stop of breathing and heartbeat, from the direct effect of lightning on the respiratory and vasomotor centers of the medulla oblongata. So-called lightning marks, tree-like light pink or red stripes often remain on the skin, disappearing when pressed with fingers (they persist for 1 - 2 days after death). They are the result of the expansion of capillaries in the area of ​​lightning contact with the body.

If struck by lightning, first aid should be immediate. In severe cases (stopping breathing and heartbeat), resuscitation is necessary, it should be provided without waiting medical workers, any witness to misfortune. Resuscitation is effective only in the first minutes after a lightning strike; starting after 10 - 15 minutes, it is, as a rule, no longer effective. Emergency hospitalization is necessary in all cases.

16.05.2017 18:00 3519

Where do thunder and lightning come from?

Everyone knows what a thunderstorm is - the flash of lightning and the roar of thunder. Many people (especially children) are even very afraid of her. But where do thunder and lightning come from? And in general, what kind of phenomenon is this?

A thunderstorm is indeed a rather unpleasant and even eerie natural phenomenon, when dark, heavy clouds cover the sun, lightning flashes, thunder rumbles, and rain pours from the sky in torrents...

And the sound that arises is nothing more than a wave caused by strong air vibrations. In most cases, the volume increases towards the end of the roll. This occurs due to the reflection of sound from clouds. This is thunder.

Lightning is a very powerful electrical discharge of energy. It occurs as a result of strong electrification of clouds or the earth's surface. Electrical discharges occur either in the clouds themselves, or between two adjacent clouds, or between a cloud and the ground.

The process of lightning occurrence is divided into the first strike and all subsequent strikes. The reason is that the very first lightning strike creates a path for electrical discharge. A negative electrical discharge accumulates at the bottom of the cloud.

A earth's surface has a positive charge. Therefore, electrons (negatively charged particles, one of the basic units of matter) located in a cloud are attracted to the ground like a magnet and rush down.

As soon as the first electrons reach the surface of the earth, a channel (a kind of passage) free for the passage of electrical discharges is created, through which the remaining electrons rush down.

Electrons near the ground are the first to leave the channel. Others are rushing to take their place. As a result, a condition is created in which all the negative energy discharge comes out of the cloud, creating a powerful flow of electricity directed into the ground.

It is at such a moment that a flash of lightning occurs, which is accompanied by peals of thunder.

Electrified clouds create lightning. But not every cloud contains enough power to penetrate the atmospheric layer. Certain circumstances are necessary for the manifestation of force and elements.

Air masses are in constant motion. Warm air goes up, and cold air goes down. When particles move, they become electrified, that is, they are saturated with electricity.

IN different parts clouds accumulate an unequal amount of energy. When there is too much of it, a flash occurs, accompanied by peals of thunder. This is the thunderstorm

What types of lightning are there? Someone might think that lightning is all the same, that a thunderstorm is a thunderstorm. However, there are several types of lightning that are very different from each other.

Linear lightning- This is the most common variety. It looks like an overgrown tree upside down. Several thinner and shorter “shoots” extend from the main canal (trunk).

The length of such lightning can reach up to 20 kilometers, and the current strength can be 20,000 amperes. Its speed is 150 kilometers per second. The temperature of the plasma filling the lightning channel reaches 10,000 degrees.

Intracloud lightning- the occurrence of this type is accompanied by changes in electric and magnetic fields, and the emission of radio waves. Such lightning is most likely to be found closer to the equator. IN temperate climate it appears extremely rarely.

If there is lightning in the cloud, then a foreign object that violates the integrity of the shell, for example, an electrified aircraft, can force it to come out. Its length can vary from 1 to 150 kilometers.

Ground lightning- This is the longest-lasting type of lightning, so its consequences can be devastating.

Since there are obstacles on its way, in order to get around them, the lightning is forced to change its direction. Therefore, it reaches the ground in the form of a small staircase. Its speed is approximately 50 thousand kilometers per second.

After the lightning has completed its path, it stops moving for several tens of microseconds, and its light weakens. Then the next stage begins: repeating the traversed path.

The most recent discharge is brighter than all previous ones, and the current in it can reach hundreds of thousands of amperes. The temperature inside the lightning fluctuates around 25,000 degrees.

Sprite lightning. This variety was discovered by scientists relatively recently - in 1989. This lightning is very rare and was discovered completely by accident. Moreover, it lasts only some tenths of 1 second.

What distinguishes Sprite from other electrical discharges is the height at which it appears - approximately 50-130 kilometers, while other types do not overcome the 15-kilometer mark. In addition, sprite lightning is distinguished by its huge diameter, which can reach 100 km.

Such lightning looks like a vertical column of light and flashes not individually, but in groups. Its color can be different and depends on the composition of the air: closer to the ground, where there is more oxygen, it is green, yellow or white. And under the influence of nitrogen, at an altitude of more than 70 km, it acquires a bright red hue.

Pearl Lightning. This lightning, like the previous one, is a rare natural phenomenon. Most often, it appears after the linear one and completely repeats its trajectory. It consists of balls located at a distance from each other and resembling beads.

Ball lightning. This is a special variety. A natural phenomenon when lightning is in the shape of a ball, shining and floating across the sky. In this case, the trajectory of its flight becomes unpredictable, which makes it even more dangerous for humans.

In most cases, ball lightning occurs in combination with other types. However, there are cases when it appeared even in sunny weather. The size of the ball can be from ten to twenty centimeters.

Its color can be blue, orange or white. And the temperature is so high that if the ball unexpectedly ruptures, the liquid surrounding it evaporates, and metal or glass objects melt.

A ball of such lightning can exist for quite a long time. When moving, it can unexpectedly change its direction, hover in the air for several seconds, or sharply deviate to one side. It appears in one copy, but always unexpectedly. The ball may descend from the clouds, or suddenly appear in the air from behind a pole or tree.

And if ordinary lightning can only strike something - a house, a tree, etc., then ball lightning is capable of penetrating into a closed space (for example, a room) through an outlet, or switched on Appliances- TV, etc.

Which lightning is considered the most dangerous?

Usually the first strike of thunder and lightning is followed by a second. This is due to the fact that the electrons in the first flash create the opportunity for a second passage of electrons. Therefore, subsequent outbreaks occur one after another with almost no time intervals, striking the same place.

Lightning emerging from a cloud with its electric discharge can cause serious harm to a person and even kill. And even if her blow does not hit a person directly, but falls nearby, the health consequences can be very bad.

To protect yourself, you must follow some rules:

So, during a thunderstorm, you should never swim in the river or sea! You must always be on dry land. In this case, it is necessary to be as close to the surface of the earth as possible. That is, there is no need to climb a tree, much less stand under it, especially if there is one in the middle of an open place.

In addition, you cannot use any mobile devices(phones, tablets, etc.) because they can attract lightning.