Where does the thunderstorm come from? What is lightning and why does it occur? Origin of thunderclouds

16.05.2017 18:00 6038

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.

And the 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.

Different parts of the cloud accumulate different amounts 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 climates 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 can penetrate into a closed space (for example, a room) through an outlet, or turned on household appliances - a 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 should not use any mobile devices (phones, tablets, etc.) because they can attract 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 the human body. Every atom has a nucleus containing positively charged protons and neutral neutrons. The exception is the simplest hydrogen atom, in the nucleus of which there is no neutron, but only one proton.

Negatively charged electrons 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.

Interesting fact: The nature of lightning lies in the electricity contained in the clouds.

Under 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.

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Now you are carrying electric charge, since the number of protons and electrons in your atoms is no longer balanced. Now try to 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 the hand and the 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.

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How does lightning appear?

Here's what happens: powerful air currents constantly circulate in a dark, huge thundercloud, pushing 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.

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.

Lightning is a giant electrical spark. When it hits buildings, it causes fires, splits large trees, and infects people. At any given time, more than 2,000 thunderstorms flash lightning in different parts of the Earth. 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

Lightning is a giant electrical spark discharge in the atmosphere, usually occurring during a thunderstorm, resulting in 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 surface of the globe is more electrically conductive than air. However, the electrical conductivity of air increases with altitude. The air is usually positively charged, and the Earth is negatively charged. Water droplets in a thundercloud are charged due to the absorption of charged tiny particles (ions) in the air. A drop falling from a cloud has a negative charge at the top and a positive charge at the bottom. Falling drops mostly absorb negatively charged particles and acquire a negative charge. In the process of swirling in the cloud, water droplets are sprayed, with small drops flying with a negative charge, and large drops flying with a positive charge. The same thing happens with ice crystals at the top of the cloud. When they split, small ice particles acquire a positive charge and are carried by ascending currents to the upper part of the cloud, and large, negatively charged particles fall to the lower part of the cloud. As a result of the separation of charges, electric fields are created in the thundercloud and in the surrounding space. With the accumulation of large volumetric charges in a thundercloud, spark discharges (lightning) occur between individual parts of the cloud or between the cloud and the earth's surface. Lightning discharges vary in appearance. The most commonly observed is linear branched lightning, sometimes ball lightning, etc.

Lightning is of great interest not only as a peculiar natural phenomenon. It makes it possible to observe an electrical discharge in a gaseous medium at a voltage of several hundred million volts and a distance between electrodes of several kilometers.

In 1750, B. Franklin proposed to the Royal Society of London to conduct an experiment with an iron rod mounted on an insulating base and mounted on a high tower. He expected that when a thundercloud approached the tower, a charge of the opposite sign would be concentrated at the upper end of the initially neutral rod, and a charge of the same sign as at the base of the cloud would be concentrated at the lower end. If the electric field strength during a lightning discharge increases sufficiently, the charge from the upper end of the rod will partially flow into the air, and the rod will acquire a charge of the same sign as the base of the cloud.

The experiment proposed by Franklin was not carried out in England, but it was carried out in 1752 in Marly near Paris by the French physicist Jean d'Alembert. He used an iron rod 12 m long inserted into a glass bottle (which served as an insulator), but did not place it on the tower. May 10 his assistant reported that when a thundercloud was over the bar, sparks occurred when a grounded wire was brought near it.

Franklin himself, unaware of the successful experiment carried out in France, in June of the same year conducted his famous experiment with a kite and observed electric sparks at the end of a wire tied to it. The following year, while studying the charges collected from the rod, Franklin determined that the bases of thunderclouds were usually negatively charged.

More detailed studies of lightning became possible at the end of the 19th century. thanks to the improvement of photographic methods, especially after the invention of an apparatus with rotating lenses, which made it possible to record rapidly developing processes. This type of camera was widely used in the study of spark discharges. It has been found that there are several types of lightning, with the most common being line, plane (in-cloud) and ball (air discharges).

Linear lightning has a length of 2-4 km and has a large current. It is formed when the electric field strength reaches a critical value and the ionization process occurs. The latter is initially created by free electrons, always present in the air. Under the influence of an electric field, electrons acquire high speeds and on their way to the Earth, colliding with air atoms, they split and ionize them. Ionization occurs in a narrow channel, which becomes conductive. The air is heating up. Through a channel of heated air, the charge from the cloud flows to the earth's surface at a speed of more than 150 km/h. This is the first stage of the process. When a charge reaches the Earth's surface between the cloud and the ground, a conductive channel is created through which charges move towards each other: positive charges from the Earth's surface and negative charges accumulated in the cloud. Linear lightning is accompanied by a strong rolling sound - thunder, reminiscent of an explosion. The sound appears as a result of the rapid heating and expansion of air in the channel, and then its equally rapid cooling and compression.

Flat lightning occurs within a thundercloud and appears as flashes of diffuse light.

Ball lightning consists of a luminous mass in the shape of a ball, somewhat smaller than a soccer ball, moving at low speed in the direction of the wind. They burst with a big bang or disappear without a trace. Ball lightning appears after linear lightning. It often enters rooms through open doors and windows. The nature of ball lightning is not yet known. Air discharges of ball lightning, starting from a thundercloud, are often directed horizontally and do not reach the earth's surface.

To protect against lightning, lightning rods are created, with the help of which the lightning charge is carried into the ground along a specially prepared safe path.

A lightning discharge usually consists of three or more repeated strikes - 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). In general, the flash lasts about a second or less. A typical lightning development process can be described as follows. First, a weakly luminous leader discharge rushes from above to the earth's surface. When he reaches it, a brightly glowing return, or main, discharge passes from the ground up through the channel laid by the leader.

The leading discharge, as a rule, moves in a zigzag manner. The speed of its spread ranges from one hundred to several hundred kilometers per second. On its way, it ionizes air molecules, creating a channel with increased conductivity, through which the reverse discharge moves upward at a speed approximately one hundred times greater than that of the leading discharge. The size of the channel is difficult to determine, but the diameter of the leading discharge is estimated at 1–10 m, and the diameter of the return discharge is several centimeters.

Lightning discharges create radio interference by emitting radio waves in a wide range - from 30 kHz to ultra-low frequencies. The greatest emission of radio waves is probably in the range from 5 to 10 kHz. Such low-frequency radio interference is “concentrated” in the space between the lower boundary of the ionosphere and the earth’s surface and can spread to distances of thousands of kilometers from the source.

Lightning: the giver of life and the engine of evolution. In 1953, biochemists S. Miller (Stanley Miller) and G. Urey (Harold Urey) showed that one of the "building blocks" of life - amino acids - can be obtained by passing an electric discharge through water in which the gases of the "primordial" atmosphere of the Earth are dissolved ( methane, ammonia and hydrogen). 50 years later, other researchers repeated these experiments and obtained the same results. Thus, the scientific theory of the origin of life on Earth assigns a fundamental role to lightning strikes. When short current pulses are passed through bacteria, pores appear in their shell (membrane), through which DNA fragments of other bacteria can pass in, triggering one of the mechanisms of evolution.

How to protect yourself from lightning using a water jet and a laser. Recently, a fundamentally new method of combating lightning was proposed. A lightning rod will be created from... a jet of liquid that will be shot from the ground directly into thunderclouds. Lightning liquid is a saline solution to which liquid polymers are added: the salt is intended to increase electrical conductivity, and the polymer prevents the jet from “breaking up” into individual droplets. The diameter of the jet will be about a centimeter, and the maximum height will be 300 meters. When the liquid lightning rod is finalized, it will be equipped with sports and children's playgrounds, where the fountain will turn on automatically when the electric field strength becomes high enough and the probability of a lightning strike is maximum. A charge will flow down a stream of liquid from a thundercloud, making lightning safe for others. Similar protection against lightning discharge can be done using a laser, the beam of which, ionizing the air, will create a channel for an electrical discharge away from crowds of people.

Can lightning lead us astray? Yes, if you use a compass. In the famous novel by G. Melville "Moby Dick" exactly such a case is described when a lightning discharge, which created a strong magnetic field, remagnetized the compass needle. However, the captain of the ship took a sewing needle, hit it to magnetize it, and replaced it with the damaged compass needle.

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

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

December 22, 2009 | Categories: Nature , Photo , Other

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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 appearance of a difference electrical potentials between neighboring clouds or between a cloud and the ground.

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

If you comb clean, dry hair with a plastic comb, it begins to be attracted to it, or even spark. After this, the comb can also attract other small objects, for example, small pieces of paper. This phenomenon is called electrification by friction.

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 of different sizes, since the temperature there is always below zero. These pieces of ice are in constant motion, caused by rising currents of 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 these 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.

The nature of electricity

Interesting fact: The nature of lightning lies in the electricity contained in the clouds.

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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 the hand and the 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.

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