Lightning

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

The nature of electricity

All bodies are made of atoms - from clouds and trees to 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 circulate around the nucleus. Positive and negative charges attract each other, so 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 see, it is also contained in atoms.

IN normal conditions the positive and negative charges of each atom balance each other, so bodies consisting of atoms usually do not carry any net charge - neither positive nor negative. As a result, contact with other objects does not cause an electrical discharge. But sometimes the balance of electrical charges in bodies can be disrupted. You may experience this yourself while at home on a cold winter day. The house is very dry and hot. You, shuffling with your bare feet, walk around the palace. Unbeknownst to you, some of the electrons from your soles transferred to the atoms of the carpet.

Related materials:

Why are lightning bolts different colors?

Now you are carrying an electrical charge because the number of protons and electrons in your atoms is no longer balanced. Now try to grab the metal door handle. A spark will jump between you and her and you will feel an electric shock. What has happened is that your body, which does not have enough electrons to achieve electrical balance, seeks to restore balance through the forces of electromagnetic attraction. And it is restored. Between hand and door handle There is a flow of electrons directed towards the hand. If the room was dark, you would see sparks. Light is visible because electrons, when they jump, emit quanta of light. If the room is quiet, you will hear a slight crackling sound.

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

How does lightning appear?

Here's what happens: in a dark, huge thundercloud, powerful air currents, which push various particles together - grains of ocean salt, dust, and so on. Just as your soles, when rubbed against a carpet, are freed from electrons, particles in a cloud, when they collide, are freed from electrons, which jump to other particles. This is how charge redistribution occurs. Some particles that have lost their electrons have a positive charge, while others that have taken on extra electrons now have a negative charge.

Related materials:

Rain on other planets

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

Many people are afraid of a terrible natural phenomenon - thunderstorms. This usually happens when the sun is covered by dark clouds, terrible thunder is booming and heavy rain is falling.

Of course, you should be afraid of lightning, because it can even kill or cause death. This has been known for a long time, that’s why they came up with various means for protection from lightning and thunder (for example, metal poles).

What's going on up there and where does the thunder come from? And how does lightning occur?

Storm clouds

Usually huge. They reach several kilometers in height. It is not visually visible how everything is seething and boiling inside these thunderous clouds. This air, including water droplets, moves at high speed from bottom to top and vice versa.

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

On the origin of thunderclouds

Before we learn where thunder comes from and how lightning occurs, let's briefly describe how thunderclouds form.

Most of these phenomena occur not over the water surface of the planet, but over the continents. In addition, thunderclouds intensively form over the continents of tropical latitudes, where the air near the earth's surface (as opposed to the air above the water surface) warms up strongly and rises quickly.

Usually, on the slopes of various elevations, a similar heated air is formed, which draws in moist air from vast areas of the earth's surface and lifts it upward.

This is how the so-called cumulus clouds are formed, which turn into thunderclouds, described just above.

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

Lightning and thunder

From those same frozen drops, pieces of ice are formed, which also move in the clouds at great speed, colliding, collapsing and charging 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 droplets of water.

Thus, two electric charges arise in a thundercloud. At the top it is negative, at the bottom it is positive. When different charges meet, a powerful one is created and lightning occurs. It became clear where it comes from. 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 occurs. This is thunder, frightening all living things on earth.

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

Ionosphere

We found out what lightning is and where it comes from. Now a little about the processes that maintain the Earth's charge.

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

Usually, in clear weather, the Earth slowly discharges (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 proportion of ions, which allows current to exist throughout the entire atmosphere. Thanks to this, although slowly, the negative charge is transferred from the earth's surface to height. Therefore, the volume of the total charge of the Earth always remains unchanged.

Today, the most common opinion is that ball lightning is a special type of charge in the shape of a ball, which exists for quite a long time and moves along an unpredictable trajectory.

Today there is no single theory of the origin of this phenomenon. There are many hypotheses, but so far none has received recognition among scientists.

Usually, as eyewitnesses testify, it occurs during a thunderstorm or 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 can even come out of some object (pillar, tree).

Some interesting facts

We found out where thunder and lightning come from. Now a little about interesting facts regarding the above-described natural phenomena.

1. The Earth experiences approximately 25 million lightning flashes each year.

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

3. There is a belief that lightning cannot strike twice in the same place. In reality this is not the case. Analysis results (by geographical map) locations of lightning strikes over the previous few years show that lightning can strike the same place several times.

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

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

Every second, approximately 50 lightning flashes occur on planet Earth.

Lightning 1882
(c) Photographer: William N. Jennings, c. 1882

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.

Physical properties of lightning

The average length of lightning is 2.5 km, some discharges extend up to 20 km in the atmosphere.

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 occur in the clouds themselves - intracloud lightning, or they can hit the ground - ground lightning. For lightning to occur, it is necessary for a cloud to form in a relatively small (but not less than some critical) volume. electric field(see atmospheric electricity) with a intensity sufficient to initiate an electrical discharge (~ 1 MV/m), and in a significant part of the cloud there would be a field with an average intensity sufficient to maintain the initiated discharge (~ 0.1-0.2 MV/ m). In lightning, the electrical energy of the cloud is converted into heat, light and sound.

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.

According to more modern concepts, ionization of the atmosphere for the passage of a discharge occurs under the influence of high-energy cosmic radiation - particles with energies of 10 12 -10 15 eV, forming a wide air shower (EAS) with a decrease in the breakdown voltage of the air by an order of magnitude from that under normal conditions.

According to one hypothesis, the particles trigger a process called runaway breakdown. Thus, electron avalanches arise, turning into threads of electrical discharges - streamers, which are highly conductive channels that, merging, give rise to a bright thermally ionized channel with high conductivity - stepped lightning leader.

The movement of the leader to the earth's surface occurs steps 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 as the leader moves to the surface of the earth at an average speed of 200,000 meters per second.

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

In the final stage, the channel ionized by the leader follows back(from bottom to top), or main, lightning discharge, characterized by currents from tens to hundreds of thousands of amperes, brightness, noticeably exceeding the brightness of the leader, and a high speed of advancement, initially reaching up to ~ 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 2000-3000 °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. But the ground is not charged, so it is generally accepted that a lightning discharge occurs from the cloud towards the ground (from top to bottom).

The main discharge often discharges only part of the cloud. Charges located at high altitudes can give rise to a new (swept) 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 over Toulouse, France. 2006

Intracloud lightning usually includes only leader stages; their length ranges from 1 to 150 km. The proportion of intracloud lightning increases as it moves toward the equator, changing from 0.5 in temperate latitudes to 0.9 in the equatorial zone. The passage of lightning is accompanied by changes in electric and magnetic fields and radio emission, the so-called atmospherics.

Flight from Kolkata to Mumbai.

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 the upper atmosphere

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

Elves

Jets

Jets are cone tubes of blue color. The height of the jets can reach 40-70 km (the lower limit of the ionosphere), jets live relatively longer than elves.

Sprites

Sprites are difficult to distinguish, but they appear in almost any thunderstorm at an altitude of 55 to 130 kilometers (the altitude of formation of “ordinary” lightning is no more than 16 kilometers). This is a kind of lightning striking upward from a cloud. This phenomenon was first recorded in 1989 by accident. Currently, very little is known about the physical nature of sprites.

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

Global lightning strike frequency (scale shows number of strikes per year per square kilometer)

Early estimates put the frequency of lightning strikes on Earth at 100 times per second. Current data from satellites, which can detect lightning in areas where there is no ground observation, puts the frequency at an average of 44 ± 5 ​​times per second, which equates to approximately 1.4 billion lightning strikes per year. 75% of this lightning strikes between or within clouds, and 25% strikes the ground.

The most powerful lightning strikes cause the birth of fulgurites.

Shock wave from lightning

A lightning discharge is an electrical explosion and is similar in some aspects to detonation. It causes a shock wave that is dangerous in the immediate vicinity. A shock wave from a sufficiently powerful lightning discharge at distances of up to several meters can cause destruction, break trees, injure and concuss people even without direct electric shock. For example, with a current rise rate of 30 thousand amperes per 0.1 millisecond and a channel diameter of 10 cm, the following shock wave pressures can be observed:

• at a distance from the center of 5 cm (border of the luminous lightning channel) - 0.93 MPa,
• at a distance of 0.5 m - 0.025 MPa (destruction of fragile building structures and human injuries),
• at a distance of 5 m - 0.002 MPa (breaking glass and temporarily stunning a person).

At greater distances, the shock wave degenerates into a sound wave - thunder.

People and lightning

Lightning is a serious threat to human life. A person or animal being struck by lightning often occurs in open spaces, since 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 cause of cessation of basic 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.

Lightning travels in a tree trunk along the path of least electrical resistance, releasing a large amount of heat, turning water into steam, which splits the tree trunk or, more often, tears off sections of bark from it, showing the lightning path. In subsequent seasons, the trees usually repair the damaged tissue and may close the entire wound, leaving only a vertical scar. If the damage is too severe, wind and pests will eventually kill the tree. Trees are natural lightning conductors, and are known to provide protection from lightning strikes to nearby buildings. When planted near a building, tall trees catch lightning, and the high biomass of the root system helps ground the lightning strike.

For this reason, you should not hide from the rain under trees during a thunderstorm, especially under tall or solitary trees in open areas.

Trees struck by lightning are used to make musical instruments, attributing to them unique properties.

Lightning and electrical installations

Lightning strikes pose a major hazard to electrical and electronic equipment. When lightning directly hits the wires in the line, an overvoltage occurs, causing destruction of the insulation of electrical equipment, and high currents cause thermal damage to the conductors. To protect against lightning surges, electrical substations and distribution networks are equipped with various types protective equipment such as arresters, non-linear surge suppressors, long-spark arresters. To protect against direct lightning strikes, lightning rods and lightning protection cables are used. Electromagnetic pulses created by lightning are also dangerous for electronic devices.

Lightning and aviation

Atmospheric electricity in general and lightning in particular pose a significant threat to aviation. A lightning strike on an aircraft causes a large current to spread through its structural elements, which can cause their destruction, fire in fuel tanks, equipment failures, and loss of life. To reduce risk metal elements external cladding aircraft are carefully electrically connected to each other, and non-metallic elements are metallized. This ensures low electrical resistance of the housing. To drain lightning current and other atmospheric electricity from the body, aircraft are equipped with arresters.

Due to the fact that the electrical capacity of an aircraft in the air is small, the “cloud-to-aircraft” discharge has significantly less energy compared to the “cloud-to-ground” discharge. Lightning is most dangerous for a low-flying airplane or helicopter, since in this case the aircraft can play the role of a conductor of lightning current from the cloud to the ground. It is known that aircraft at high altitudes are relatively often struck by lightning, and yet, cases of accidents for this reason are rare. At the same time, there are many known cases of aircraft being struck by lightning during takeoff and landing, as well as while parked, which resulted in disasters or destruction of the aircraft.

Lightning and surface ships

Lightning also poses a very big threat to surface ships due to the fact that the latter are elevated above the sea surface and have many sharp elements (masts, antennas) that are concentrators of electric field strength. In the days of wooden sailing ships with a high specific resistance of the hull, a lightning strike almost always ended tragically for the ship: the ship burned down or was destroyed, and people died from electric shock. Riveted steel ships were also vulnerable to lightning. The high resistivity of the rivet seams caused significant local heat generation, which led to the occurrence of an electric arc, fires, destruction of the rivets and the appearance of water leaks in the body.

The welded hull of modern ships has low resistivity and ensures safe spreading of lightning current. The protruding elements of the superstructure of modern ships are reliably electrically connected to the hull and also ensure the safe spread of lightning current.

Human activities that cause lightning

During a ground-based nuclear explosion, a fraction of a second before the arrival of the boundary of the fiery hemisphere, several hundred meters (~400-700 m when compared with an explosion of 10.4 Mt) from the center, the gamma radiation that reaches it produces an electromagnetic pulse with a intensity of ~100-1000 kV/ m, causing lightning discharges striking from the ground upward before the arrival of the border of the fiery hemisphere.

see also

	lightning in Wiktionary
	Category:Lightning on Wikimedia Commons

Notes

1. Ermakov V.I., Stozhkov Yu.I. Physics of thunderclouds // Physics Institute them. P.N. Lebedeva, RAS, M. 2004: 37
2. Cosmic rays blamed for lightning Lenta.Ru, 09.02.2009
3. Red Elves and Blue Jets
4. ELVES, a primer: Ionospheric Heating By the Electromagnetic Pulses from Lightning
5. Fractal Models of Blue Jets, Blue Starters Show Similarity, Differences to Red Sprites
6. V.P. Pasko, M.A. Stanley, J.D. Matthews, U.S. Inan, and T.G. Wood (March 14, 2002) "Electrical discharge from a thundercloud top to the lower ionosphere," Nature, vol. 416, pages 152-154.
7. The appearance of UFOs was explained by sprites. lenta.ru (24.02.2009). Archived from the original on August 23, 2011. Retrieved January 16, 2010.
8. John E. Oliver Encyclopedia of World Climatology. - National Oceanic and Atmospheric Administration, 2005. - ISBN 978-1-4020-3264-6
9. . National Oceanic and Atmospheric Administration. Archived
10. . NASA Science. Science News. (December 5, 2001). Archived from the original on August 23, 2011. Retrieved April 15, 2011.
11. K. BOGDANOV “LIGHTNING: MORE QUESTIONS THAN ANSWERS.” “Science and Life” No. 2, 2007
12. Zhivlyuk Yu.N., Mandelstam S.L. On the temperature of lightning and the force of thunder // JETP. 1961. T. 40, issue. 2. pp. 483-487.
13. N. A. Kun “Legends and Myths of Ancient Greece” LLC “AST Publishing House” 2005-538, p. ISBN 5-17-005305-3 Pages 35-36.
14. Editors: Mariko Namba Walter,Eva Jane Neumann Fridman Shamanism: an encyclopedia of world beliefs, practices, and culture. - ABC-CLIO, 2004. - T. 2. - P. 442. -

Have you ever wondered why birds sit on high-voltage wires, and a person dies when he touches the wires? Everything is very simple - they sit on a wire, but no current flows through the bird, but if the bird flaps its wing, simultaneously touching two phases, it will die. This is how they usually die big birds such as storks, eagles, falcons.

Likewise, a person can touch a phase and nothing will happen to him if no current flows through him; for this you need to wear rubberized boots and God forbid you touch a wall or metal.

Electric current can kill a person in a split second; it strikes without warning. Lightning strikes the earth one hundred times per second and over eight million times per day. This force of nature is five times hotter than the surface of the sun. The electrical discharge strikes with a force of 300,000 amperes and a million volts in a split second. In our daily lives, we think we can control the electricity that powers our homes, outdoor lights, and now our cars. But electricity in its original form cannot be controlled. And lightning is electricity on a huge scale. And yet lightning remains a big mystery. It can strike unexpectedly and its path can be unpredictable.

Lightning in the sky does no harm, but one in ten lightning strikes the surface of the earth. Lightning is divided into many branches, each of which is capable of striking a person located at the epicenter. When a person is struck by lightning, the current can pass from one person to another if they come into contact.

There is a rule of thirty and thirty: if you see lightning and hear thunder less than thirty seconds later, you must seek shelter, and then you must wait thirty minutes from the last clap of thunder before going outside. But lightning does not always obey a strict order.

There is such an atmospheric phenomenon as thunder from a clear sky. Often lightning, leaving a cloud, travels up to sixteen kilometers before striking the ground. In other words, lightning can appear out of nowhere. Lightning needs wind and water. When strong winds raise moist air, creating conditions for the emergence of destructive thunderstorms.

It is impossible to decompose into components something that fits into a millionth of a second. One false belief is that we see lightning as it travels to the ground, but what we actually see is the lightning's return path into the sky. Lightning is not a unidirectional strike to the ground, but is actually a ring, a path in two directions. The flash of lightning that we see is the so-called return stroke, the final phase of the cycle. And when the return stroke of lightning heats up the air, its calling card appears - thunder. The return path of lightning is the part of lightning that we see as a flash and hear as thunder. A reverse current of thousands of amperes and millions of volts rushes from the ground to the cloud.

Lightning regularly electrocutes people indoors. It can enter a structure in different ways, through drainpipes and water pipes. Lightning can penetrate electrical wiring whose current strength is an ordinary house does not reach two hundred amperes and overloads the electrical wiring in jumps from twenty thousand to two hundred thousand amperes. Perhaps the most dangerous path in your home leads directly to your hand through the phone. Nearly two-thirds of indoor electric shocks occur when people pick up a landline telephone during a lightning strike. Cordless phones are safer during thunderstorms, but lightning can electrocute someone standing near the phone's base. Even a lightning rod cannot protect you from all lightning, since it is not capable of catching lightning in the sky.

About the nature of lightning

There are several different theories explaining the origin of lightning.

Typically, the bottom of the cloud carries a negative charge and the top carries a positive charge, making the cloud-ground system like a giant capacitor.

When the electrical potential difference becomes large enough, a discharge known as lightning occurs between the ground and the cloud, or between two parts of the cloud.

Is it dangerous to be in a car during lightning?

In one of these experiments, a meter-long artificial lethal lightning was directed at steel roof car in which there was a person. Lightning passed through the casing without harming a person. How did this happen? Since charges on a charged object repel each other, they tend to move as far apart as possible.

In the case of a hollow mechanical ball pi cylinder, the charges are distributed over the outer surface of the object. Similarly, if lightning l gives in metal roof car, then the repelling electrons will spread extremely quickly over the surface of the car and go through its body into the ground. Therefore, lightning along the surface of a metal car goes into the ground and does not get inside the car. For the same reason, a metal cage is perfect protection against lightning. As a result of artificial lightning striking a car with a voltage of 3 million volts, the potential of the car and the body of the person in it increases to almost 200 thousand volts. At the same time, a person does not experience the slightest sign of an electric shock, since there is no potential difference between any points of his body.

This means that staying in a well-grounded building with metal frame, and there are many of them in modern cities.

How can we explain that birds sit on the wires completely calmly and with impunity?

The body of a sitting bird is like a branch of a chain ( parallel connection). The resistance of this branch with the bird is much greater than the resistance of the wire between the bird's legs. Therefore, the current strength in the bird’s body is negligible. If a bird, sitting on a wire, touched the pole with its wing or tail, or otherwise connected with the ground, it would be instantly killed by the current that would rush through it into the ground.

Interesting facts about lightning

The average length of lightning is 2.5 km. Some discharges extend up to 20 km in the atmosphere.

Lightning is beneficial: they manage to snatch millions of tons of nitrogen from the air, bind it and send it into the ground, fertilizing the soil.

Saturn's lightning is a million times stronger than Earth's.

A lightning discharge usually consists of three or more repeated discharges - pulses following the same path. The intervals between successive pulses are very short, from 1/100 to 1/10 s (this is what causes lightning to flicker).

About 700 lightning flashes on Earth every second. World centers of thunderstorms: the island of Java - 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.

The air in the zone of the lightning channel almost instantly heats up to a temperature of 30,000-33,000 ° C. On average, about 3,000 people die from lightning strikes in the world every year

Statistics show that every 5,000-10,000 flight hours there is one lightning strike on an aircraft; fortunately, almost all damaged aircraft continue to fly.

Despite the crushing power of lightning, protecting yourself from it is quite simple. During a thunderstorm, you should leave immediately open places, in no case should you hide under separate trees, or be near high masts and power lines. You should not hold steel objects in your hands. Also, during thunderstorms, you cannot use radio communications, mobile phones. Televisions, radios and electrical appliances must be turned off indoors.

Lightning rods protect buildings from lightning damage for two reasons: they allow the charge induced on the building to flow into the air, and when lightning strikes the building, they take it into the ground.

If you find yourself in a thunderstorm, you should avoid taking shelter near single trees, hedges, elevated places and being in open spaces.

Add site to bookmarks

Lightning from an electrical point of view

The electrical nature of lightning was revealed in the research of the American physicist B. Franklin, on whose initiative 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 in which he described an experiment using a 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.

How does lightning form? 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.

Scheme of lightning occurrence: a - formation; b - category.

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 with a strength sufficient to initiate an electrical discharge (~ 1 MV/m) is formed, and in a significant part of the cloud there is a field with an average strength sufficient to maintain the started discharge (~ 0.1-0.2 MV/m). In lightning, the electrical energy of the cloud is converted into heat and light.

Linear lightning is usually observed, which belongs to the so-called electrodeless discharges, since they begin (and end) in accumulations of charged particles. This determines some of their 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 square kilometers.

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).

Ground lightning

Development diagram of ground lightning: a, b - two leader stages; 1 - cloud; 2 - streamers; 3 - step leader channel; 4 - channel crown; 5 - pulse corona on the channel head; c - formation of the main lightning channel (K).

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 electrons, 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.

According to more modern concepts, the discharge is initiated by high-energy cosmic rays, which trigger a process called runaway electron breakdown. Thus, 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, followed by a stop and weakening of the glow again. These processes are repeated as the leader moves to the surface of the earth at an average speed of 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 at high altitudes can give rise to a new (swept) 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 proportion of intracloud lightning increases as it moves toward the equator, changing from 0.5 in temperate latitudes to 0.9 in the equatorial zone. 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.

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

People and lightning

Lightning is a serious threat to human life. A person or animal being struck by lightning often occurs in open spaces, because... The electric current follows the shortest path "thundercloud-ground". Often lightning strikes trees and transformer installations on the railway, causing them to catch fire.

It is impossible to be struck by ordinary linear lightning inside a building, but there is an opinion that the 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.

In the body of lightning victims, the same pathological changes are observed as in case of electric shock. The victim loses consciousness, falls, may experience convulsions, and often stops breathing and heartbeat. You can usually find “current marks” on the body—the places where electricity enters and exits.

These are tree-like light pink or red stripes that disappear 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. In case of death, the cause of cessation of basic vital functions is the sudden stop of breathing and heartbeat from the direct effect of lightning on the respiratory and vasomotor centers of the medulla oblongata.

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

Victims of lightning

In mythology and literature:

• Asclepius (Aesculapius), son of Apollo, the god of doctors and medical art, not only healed, but also revived the dead. To restore the broken world order, Zeus struck him with his lightning;
• Phaeton, the son of the sun god Helios, once undertook to drive his father’s solar chariot, but could not restrain the fire-breathing horses and almost destroyed the Earth in a terrible flame. An angry Zeus pierced Phaeton with lightning.

Historical figures:

• Russian academician G.V. Richman - died from a lightning strike in 1753;
• People's Deputy of Ukraine, ex-governor of the Rivne region V. Chervoniy died from a lightning strike on July 4, 2009.

• Roy Sally Wang survived after being struck by lightning seven times;
• American Major Summerford died after long illness(the result of a third lightning strike). The fourth lightning completely destroyed his monument in the cemetery;
• Among the Andean Indians, a lightning strike is considered necessary to achieve the highest levels of shamanic initiation.

Trees and lightning

Tall trees are frequent targets for lightning. You can easily find multiple lightning scars on long-lived relict trees. A single standing tree is thought to be more likely to be struck by lightning, although in some forested areas lightning scars can be seen on almost every tree. Dry trees catch fire when struck by lightning. Most often, lightning strikes are directed at oak, least often at beech, which apparently depends on the different amounts of fatty oils in them, which represent great resistance to electricity.

Lightning passes through a tree trunk along the path of the smallest electrical resistance, with the release of a large amount of heat, turning water into steam, which splits the tree trunk or, more often, tears off sections of the bark from it, showing the path of lightning.

In subsequent seasons, the trees usually repair the damaged tissue and may close the entire wound, leaving only a vertical scar. If the damage is too severe, wind and pests will eventually kill the tree. Trees are natural lightning conductors and are known to provide protection from lightning strikes to nearby buildings. Tall trees planted near a building catch lightning, and the high biomass of the root system helps ground the lightning strike.

Musical instruments are made from trees struck by lightning, attributing unique properties to them.