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Lightning is like a miracle of nature. Types of lightning: linear, intra-cloud, ground. Lightning discharge. How ball lightning is formed The emergence of lightning physics

Lightning is one of those natural phenomena that have long instilled fear in the human race. The greatest minds, such as Aristotle or Lucretius, sought to understand its essence. They believed that this is a ball, consisting of fire and sandwiched in water vapor of clouds, and, increasing in size, it breaks through them and falls to the ground with a rapid spark.

The concept of lightning and its origin

Most often, lightning is formed in which are of a fairly large size. The upper part can be located at an altitude of 7 kilometers, and the lower one - only 500 meters above the ground. Taking into account the atmospheric temperature of the air, we can come to the conclusion that at the level of 3-4 km, the water freezes and turns into ice floes, which, colliding with each other, become electrified. Those that have the largest size get a negative charge, and the smallest ones get a positive charge. Based on their weight, they are evenly distributed in the cloud over the layers. Approaching each other, they form a plasma channel, from which an electric spark, called lightning, is obtained. It received its broken shape due to the fact that on the way to the ground, various air particles are often found, which form obstacles. And to get around them, you have to change the trajectory.

Physical description of lightning

A lightning discharge releases 109 to 1010 joules of energy. Such a colossal amount of electricity is largely consumed to create a flash of light, which is otherwise called thunder. But even a small part of lightning is enough to do unthinkable things, for example, its discharge can kill a person or destroy a building. Another interesting fact suggests that this natural phenomenon is capable of melting sand, forming hollow cylinders. This effect is achieved due to high temperature inside the lightning, it can reach 2000 degrees. The time of hitting the ground is also different, it cannot be more than a second. As for the power, the pulse amplitude can reach hundreds of kilowatts. Combining all these factors, the strongest natural discharge of current is obtained, which brings death to everything that it touches. Everything existing species lightning is very dangerous, and meeting with them is extremely undesirable for humans.

Thunder formation

It is impossible to imagine all types of lightning without a thunderclap, which does not carry the same danger, but in some cases it can lead to network failure and other technical problems. It arises from the fact that a warm wave of air, heated by lightning to a temperature hotter than the sun, collides with a cold one. The resulting sound is nothing more than a wave caused by vibrations in the air. In most cases, the volume increases towards the end of the roll. This is due to the reflection of sound from the clouds.

What are lightning bolts

It turns out they are all different.

1. Linear lightning is the most common type. The electric roll looks like a tree overgrown upside down. Several thinner and shorter "branches" extend from the main canal. The length of such a discharge can reach 20 kilometers, and the current strength is 20,000 amperes. The speed of movement is 150 kilometers per second. The temperature of the plasma filling the lightning channel reaches 10,000 degrees.

2. Intra-cloud lightning - the origin of this type is accompanied by changes in electric and magnetic fields, radio waves are also emitted. Such a roll is most likely to be found closer to the equator. In temperate latitudes, 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 plane or a metal cable, can also induce it to get out. The length can vary from 1 to 150 kilometers.

3. Ground lightning - given view goes through several stages. At the first of them, impact ionization begins, which is created at the beginning by free electrons, they are always present in the air. Under the action of an electric field, elementary particles acquire high speeds and head towards the ground, colliding with the molecules that make up the air. Thus, electron avalanches appear, otherwise called streamers. They are channels that, merging with each other, cause bright, thermally insulated lightning. She reaches the ground in the form of a small staircase, because she encounters obstacles in her path, and in order to get around them, she changes direction. The speed of movement is approximately 50,000 kilometers per second.

After the lightning has passed its way, it stops moving for several tens of microseconds, while the light weakens. After that, the next stage begins: repetition of the path traveled. The very last discharge is brighter than all the previous ones, the current strength in it can reach hundreds of thousands of amperes. The temperature inside the channel hovers around 25,000 degrees. This type of lightning is the longest, so the consequences can be devastating.

Pearl zippers

Answering the question about what kind of lightning there are, such a rare natural phenomenon should not be overlooked. Most often, the discharge passes after the linear one and completely repeats its trajectory. Only now it looks like balls located at a distance from each other and resembling beads made of precious material. Such lightning is accompanied by the loudest and rolling sounds.

Ball lightning

A natural phenomenon when lightning takes the form of a ball. In this case, the trajectory of its flight becomes unpredictable, which makes it even more dangerous for humans. In most cases, such an electric ball occurs in conjunction with other species, but the fact of its appearance even in sunny weather has been recorded.

How it is formed This is the question most often asked by people who are faced with this phenomenon. As everyone knows, some things are excellent conductors of electricity, so it is in them, accumulating their charge, that the ball begins to emerge. It can also spawn from the main lightning bolt. Eyewitnesses claim that it simply arises out of nowhere.

The diameter of a lightning bolt ranges from a few centimeters to a meter. As for the color, there are several options: from white and yellow to bright green, it is extremely rare to find a black electric ball. After a rapid descent, it moves horizontally, about a meter from the surface of the earth. Such lightning can unexpectedly change its trajectory and just as suddenly disappear, releasing enormous energy, due to which various objects melt or even completely collapse. She lives from ten seconds to several hours.

Sprite Lightning

More recently, in 1989, scientists discovered another type of lightning, which was named sprite... The discovery happened quite by accident, because the phenomenon is extremely rare and lasts only tenths of a second. They are distinguished from others by the height at which they appear - about 50-130 kilometers, while other subspecies do not overcome the 15-kilometer line. Also, sprite lightning has a huge diameter, which reaches 100 km. They appear vertical and flash in groups. Their color differs depending on the composition of the air: closer to the ground, where there is more oxygen, they are green, yellow or white, but under the influence of nitrogen, at an altitude of more than 70 km, they acquire a bright red hue.

Behavior during a thunderstorm

All types of lightning pose an extraordinary danger to health and even human life. To avoid electric shock, the following rules should be followed in open areas:

In this situation, the highest objects fall into the risk group, so open areas should be avoided. To get lower, it is best to sit down and put your head and chest on your knees, in case of defeat, this position will protect all vital organs. In no case should you lie down flat, so as not to increase the area of possible hit.
Also, do not hide under tall trees and Undesirable shelter will be unprotected structures or metal objects (for example, a picnic shelter).
During a thunderstorm, you must immediately get out of the water, because it is a good conductor. Getting into it, a lightning discharge can easily spread to a person.
Under no circumstances should a mobile phone be used.
To provide first aid to the victim, it is best to perform cardiopulmonary resuscitation and immediately call the rescue service.

House rules

There is also a risk of injury indoors.

If a thunderstorm starts outside, the first step is to close all windows and doors.
Disconnect all electrical appliances.
Keep away from wired telephones and other cables, they are excellent conductors of electricity. Metal pipes have the same effect, so you should not be near the plumbing.
Knowing how it is formed ball lightning and how unpredictable its trajectory is, if it does get into the room, you must immediately leave it and close all windows and doors. If these actions are not possible, it is better to stand still.

Nature is still beyond the control of man and carries many dangers. All types of lightning are, in their essence, the most powerful electrical discharges, which are several times higher in power than all artificially man-made current sources.

Target: develop their horizons and creativity, acquaint them with interesting facts.

Classroom plan

I. Introductory remarks.

II. How does rain form? Discussion of the situation.

III. Presentation of theoretical material.

IV. Final word.

Class hour

I. Introduction

Where does the rain come from? Through what processes does water from the surface of oceans, seas and lakes appear in the sky and rain down? Let's take a look at how rain is formed.

II. How does rain form? Discussion of the situation.

Rain is formed due to the water cycle in nature. In science, it is called the "hydrological cycle". What is its essence? The sun heats up the surface of the Earth enough to start the process of evaporation of water from wherever it is - from puddles, rivers, lakes, seas, oceans, etc.

III. Presentation of theoretical material.

Due to evaporation, water molecules rise high into the air, forming clouds and clouds. The wind carries them away in the sky for many kilometers. Water molecules combine, gradually forming heavier and heavier structures. Eventually a drop forms, which is already quite heavy. Because of this, the drop flies down. When there are many of these drops, it rains. It can be light, a little drizzling, or it can be a heavy downpour.

Very important feature the water cycle in nature is that as a result of evaporation, seas and oceans lose more water than they receive during precipitation. On land, the opposite is true - the amount of water received is much greater during precipitation than its loss during evaporation. This natural mechanism allows maintaining a strictly defined balance between the ratio of the amount of water in the seas and on land, which is important for the continuous process of the water cycle and equal amount of precipitation around the globe.

This is how the water cycle occurs in nature, which is necessary for the development of life on Earth. And rain is one of the stages of the water cycle

The rainbow as a physical phenomenon

A rainbow is one of those unusual optical phenomena with which nature sometimes pleases a person. For a long time, people have tried to explain the origin of the rainbow. Science has come close to understanding the process of occurrence of a phenomenon, when in mid XVII century Czech scientist Mark Marci discovered that the light beam is heterogeneous in its structure. Somewhat later, Isaac Newton studied and explained the phenomenon of dispersion of light waves. As is now known, a light beam is refracted at the interface of two transparent media with different densities.

Instructions

As Newton established, a white light beam is obtained as a result of the interaction of rays of different colors: red, orange, yellow, green, blue, blue, violet. Each color is characterized by a specific wavelength and vibration frequency. At the boundary of transparent media, the speed and length of light waves change, the frequency of the oscillations remains the same. Each color has its own refractive index. Least of all, the red ray deflects from the previous direction, a little more orange, then yellow, etc. The violet ray has the highest refractive index. If a glass prism is installed in the path of a light beam, then it not only deflects, but also disintegrates into several rays of different colors.

And now about the rainbow. In nature, the role of a glass prism is played by raindrops, which the sun's rays collide with when passing through the atmosphere. Since the density of water is greater than the density of air, the light beam at the interface between the two media is refracted and decomposed into components. Further, the color rays move already inside the drop until they collide with its opposite wall, which is also the boundary of two media, and, moreover, has mirror properties. Most of the luminous flux after secondary refraction will continue to move in the air behind the raindrops. Some part of it will be reflected from back wall drops and will be released into the air after secondary refraction on its front surface.

This process takes place at once in a multitude of drops. To see a rainbow, the observer must stand with his back to the Sun and face the wall of rain. Spectral rays come out of raindrops at different angles. From each drop, only one ray falls into the eye of the observer. The rays emanating from adjacent droplets merge to form a colored arc. Thus, from the topmost drops, red rays fall into the eye of the observer, orange ones from those below, and so on. The violet rays are most strongly deflected. The purple stripe will be at the bottom. A semicircular rainbow can be seen when the Sun is at an angle of no more than 42 ° to the horizon. The higher the sun rises, the smaller sizes rainbows.

Actually, the described process is somewhat more complicated. The light beam inside the droplet is reflected multiple times. In this case, not one color arc can be observed, but two - a rainbow of the first and second order. The outer arc of the first-order rainbow is colored red, the inner one is purple. The opposite is true for a second-order rainbow. It usually looks much paler than the first, because with multiple reflections, the intensity of the light flux decreases.

Lightning as a physical phenomenon

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

First, it is necessary to find out the features of the "behavior" of this natural phenomenon. As known, lightning Is an electrical discharge that rushes from heaven to earth. Meeting any obstacles on its way, lightning collides with them. Thus, very often a lightning strike strikes tall trees, telegraph poles, high-rise buildings that are not protected by a lightning rod. Therefore, if you are within the city, do not even try to hide under the crowns of trees and do not lean against the walls of tall buildings. That is, you need to remember the main rule: lightning strikes that which is above all.

Television antennas, which are located in large numbers on the roofs of residential buildings, perfectly “attract” lightning. Therefore, if you are in the house, do not turn on any electrical appliances, including the TV. It is also advisable to turn off the light, since the electrical wiring is no less susceptible to shock lightning.

If lightning caught you in a forest or field, then you must remember the first rule and not lean against trees or pillars. It is advisable to generally creep to the ground and not rise until the end thunderstorms... Of course, if you are in a field where you are the tallest subject, the risk is most likely. Therefore, it will not be superfluous to find a ravine or just a lowland, which will be your refuge.

So we can conclude that if, while in your own apartment, you hear threatening peals of thunder and feel the approach of a thunderstorm, do not tempt fate, do not go out and wait out this natural phenomenon at home

REASONS for the appearance of lightning

Lightning discharges ( lightning) is the most common source of powerful natural electromagnetic fields. Lightning is a type of gas discharge with a very long spark length. The total length of the lightning channel reaches several kilometers, and a significant part of this channel is located inside the thundercloud. lightning The cause of lightning is the formation of a large volumetric electric charge.

Ordinary lightning source are thunderstorm cumulonimbus clouds, which carry an accumulation of positive and negative electric charges in the upper and lower parts of the cloud and form electric fields of increasing intensity around this cloud. The formation of such volumetric charges of different polarity in the cloud (cloud polarization) is associated with condensation due to the cooling of water vapors of the ascending streams of warm air on positive and negative ions (condensation centers) and the separation of charged moisture droplets in the cloud under the action of intense ascending thermal air currents. Due to the fact that several accumulations of charges isolated from each other are formed in the cloud (charges of negative polarity accumulate in the lower part of the cloud).

Thunder- a sound phenomenon in the atmosphere accompanying a lightning discharge. Thunder is the vibration of the air under the influence of a very rapid increase in pressure in the path of lightning, due to heating up to about 30,000 ° C. Thunderbolts occur due to the fact that lightning has a considerable length, and the sound from its different parts does not reach the observer's ear at the same time. The occurrence of rumblings is also facilitated by the reflection of sound from clouds and the refraction of sound waves propagating along different paths. In addition, the discharge itself does not occur instantly, but continues for some time.

The volume of thunderclaps can be up to 120 decibels.

Distance to thunderstorm

By measuring the time elapsed between a flash of lightning and a thunderclap, you can roughly determine the distance at which a thunderstorm is located. The speed of light is several orders of magnitude higher than the speed of sound; it can be neglected and only the speed of sound can be taken into account, which is 300-360 meters per second at an air temperature of −50 ° C to + 50 ° C. Multiplying the time between a flash of lightning and a thunderbolt in seconds by this value, you can judge the proximity of a thunderstorm. Three seconds of time between flash and sound corresponds to approximately one kilometer of distance. By comparing several such measurements, one can judge whether the thunderstorm is approaching the observer (the interval between lightning and thunder decreases) or receding (the interval increases). It should be borne in mind that lightning has a significant length (up to several kilometers), and, noting the first heard sounds of thunder, we determine the distance to the nearest point of lightning. As a rule, thunder is heard at a distance of up to 15-20 kilometers, so if an observer sees lightning, but does not hear thunder, then the thunderstorm is at a distance of more than 20 kilometers.

IV. Final word.

Guys, I hope that now you will know about rain, rainbow, lightning and thunder, not only how about natural phenomena but also physical. And about other physical phenomena: aurora borealis, echoes, waves at sea, volcanoes and geysers, earthquakes, we will talk in the next classroom hours.

Municipal educational institution

Gymnasium "Laboratory of Salakhov"

Creative work in physics

on the topic of: Electrical phenomena in nature: lightning

Story

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

Physical properties of lightning

Average length lightning strikes 2.5 km, some discharges extend in the atmosphere for a distance of up to 20 km.

Lightning formation

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

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

Ground lightning

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

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

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

V final stage a reverse (bottom-up) or main lightning discharge follows along the channel ionized by the leader, characterized by currents from tens to hundreds of thousands of amperes, a brightness significantly exceeding the leader's brightness, and a high speed of advance, at first reaching ~ 100,000 kilometers per second, and in 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 is several centimeters. After the passage of the current pulse, the ionization of the channel and its luminescence become weaker. In the final stage, the lightning current can last for hundredths and even tenths of a second, reaching hundreds and thousands of amperes. Such lightning strikes are called lingering; they most often cause fires.

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 a speed of thousands of kilometers per second. The brightness of its luminescence is close to the brightness of the stepped leader. When the arrow-shaped leader reaches the surface of the earth, a second main blow follows, similar to the first. Usually lightning includes several repeated discharges, but their number can go up to several dozen. The duration of multiple lightning can exceed 1 sec. The displacement of the channel of multiple lightning by the wind creates the so-called ribbon lightning - a luminous strip.

Intra-cloud lightning

Intracloud lightning usually includes only leader stages; their length ranges from 1 to 150 km. The share of intracloud lightning increases as it moves to 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. The likelihood of a lightning strike on a ground object increases with an increase in its height and with an increase in the electrical conductivity of the soil on the surface or at a certain 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 sustain the discharge, but not sufficient for its occurrence, a long metal cable or plane can play the role of a lightning initiator - especially if it is highly electrically charged. Thus, sometimes lightning is "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 strikes six times a year."

The most powerful lightning bolts cause the birth of Fulgurites.

People and lightning

Lightning is a serious threat to human life. A person or an animal is often struck by lightning in open spaces. the electric current follows the shortest path "thunderstorm cloud-ground". Lightning often strikes trees and transformer installations on the railway, causing them to catch fire. It is impossible to be struck by an ordinary linear lightning inside a building, however, there is an opinion that the so-called ball lightning can penetrate through cracks and open windows. Normal lightning strikes are hazardous to rooftop television and radio antennas and network equipment.

In the body of the victims, the same pathological changes are noted as in the case of electric shock. The victim loses consciousness, falls, convulsions may occur, breathing and heartbeat often stop. On the body, you can usually find "current marks", places of entry and exit of electricity. In the event of a fatal outcome, the cause of the termination of basic vital functions is a sudden cessation of breathing and heartbeat, from the direct action of lightning on the respiratory and vasomotor centers of the medulla oblongata. The so-called lightning marks often remain on the skin, tree-like light pink or red stripes that disappear when pressed with fingers (persist for 1 - 2 days after death). They are the result of expansion of capillaries in the zone of contact of lightning with the body.

When struck by lightning, first aid should be urgent. In severe cases (cessation of breathing and heartbeat), resuscitation is necessary, it should be provided, without waiting for medical workers, any witness of the misfortune. Resuscitation is effective only in the first minutes after being struck by lightning, started after 10-15 minutes, as a rule, it is no longer effective. Emergency hospitalization is required in all cases.

Lightning victims

1. In mythology and literature:

1. Asclepius, Aesculapius - the son of Apollo - the god of doctors and medical arts, not only healed, but also revived the dead. To restore the disturbed world order, Zeus struck him with his lightning.

2. Phaethon - the son of the sun god Helios - once took control of his father's solar chariot, but did not hold back the fire-breathing horses and almost destroyed the Earth in a terrible flame. Angry Zeus pierced Phaethon with lightning.

2. Historical figures:

1. Russian academician GV Rikhman - died in 1753 from a lightning strike.

2. People's Deputy of Ukraine, ex-governor of the Rivne region V. Chervoniy on July 4, 2009 died from a lightning strike.

Roy Sullivan survived seven lightning strikes.

· American Major Summerford died after a long illness (the result of being struck by the third lightning). The fourth lightning completely destroyed his memorial in the cemetery.

· Among the Andean Indians, a lightning strike is considered necessary to achieve the highest levels of shamanic initiation.

Trees and lightning

Lightning-struck Poplar Trunk

Tall trees are a common target for lightning. Long-lived relict trees can easily be found with multiple lightning scars. A single tree is believed 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 from a lightning strike. Most often, lightning strikes are directed to oak, less often to beech, which, apparently, depends on the different amounts of fatty oils in them, which represent a large resistance to electricity.

Lightning travels in a tree trunk along the path of least electrical resistance, emitting a large number heat, converting water into steam, which splits the trunk of the tree or more often tears off sections of the bark from it, showing the path of lightning. In the following seasons, trees usually repair damaged tissue and can cover the wound entirely, leaving only a vertical scar. If the damage is too severe, wind and pests will eventually kill the tree. Trees are natural lightning rods and are known to provide lightning protection for nearby buildings. Planted near the building, tall trees catch lightning, and the high biomass of the root system helps ground the lightning strike.

From trees struck by lightning they make musical instruments attributing unique properties to them.

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Lightning as a natural phenomenon

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

The nature and causes of lightning

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

Thunderstorms can be divided into local, frontal, night, in the mountains. Most often, a person is faced with local or thermal thunderstorms. These thunderstorms occur only in hot weather with high humidity. atmospheric air... As a rule, occur in the summer at midday or afternoon (12-16 hours). Water vapor in the ascending stream of warm air condenses at a height, while a lot of heat is released and the ascending air currents are warmed up. The rising air is warmer compared to the surrounding air, it expands in volume until it turns into a thundercloud. Large thunderstorm clouds contain ice crystals and water droplets. As a result of their crushing and friction with each other and with the air, positive and negative charges are formed, under the influence of which a strong electrostatic field arises (the intensity of the electrostatic field can reach 100,000 V / m). And the potential difference between separate parts clouds, clouds or cloud and earth reaches enormous magnitudes. When the critical intensity of the electric air is reached, an avalanche-like ionization of air occurs - a spark discharge of lightning.

A frontal thunderstorm occurs when masses of cold air penetrate an area dominated by warm weather... Cold air displaces warm air, while the latter rises to a height of 5-7 km. Warm air layers invade inside vortices of various directions, a squall is formed, strong friction between air layers, which contributes to the accumulation of electric charges. The length of a frontal thunderstorm can reach 100 km. Unlike local thunderstorms, after frontal thunderstorms it usually gets colder. A night thunderstorm is associated with the cooling of the earth at night and the formation of eddy currents of the rising air. A thunderstorm in the mountains is explained by the difference in solar radiation to which the southern and northern slopes of the mountains are exposed. Night and mountain thunderstorms are mild and short-lived.

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

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

A lightning discharge develops in a few thousandths of a second; at such high currents, the air in the zone of the lightning channel almost instantly heats up to a temperature of 30,000-33,000 ° C. As a result, the pressure rises sharply, the air expands - a shock wave arises, accompanied by a sound pulse - thunder. Due to the fact that on tall pointed objects the intensity of the electric field created by the static electric charge of the cloud is especially high, a glow appears; As a result, air ionization begins, a glow discharge arises and reddish tongues of glow appear, at times shortening and again lengthening. Do not try to extinguish these lights as no combustion. At a high electric field strength, a beam of glowing filaments may appear - a corona discharge, which is accompanied by hiss. Linear lightning can also occasionally occur in the absence of thunderclouds. It is not by chance that the saying arose - "out of the blue."

Ball lightning opening

lightning discharge ball electric

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

But already in 1838 in the "Yearbook" of the French bureau geographic longitudes a review was published by the famous astronomer and physicist Dominique François Arago. Subsequently, he became the initiator of the experiments of Fizeau and Foucault on measuring the speed of light, as well as the work that led Le Verrier to the discovery of Neptune. Based on the then known descriptions of ball lightning, Arago came to the conclusion that many of these observations cannot be considered an illusion. Over the 137 years that have passed since the publication of Arago's review, new eyewitness accounts and photographs have appeared. Dozens of theories were created, extravagant, witty, those that explained some of the well-known properties of ball lightning, and those that did not stand up to elementary criticism. Faraday, Kelvin, Arrhenius, Soviet physicists Ya.I. Frenkel and P.L. Kapitsa, many well-known chemists, and finally, specialists from the American National Commission on Astronautics and Aeronautics NASA tried to investigate and explain this interesting and formidable phenomenon. Ball lightning continues to remain a mystery to this day.

The nature of ball lightning

What facts should scientists connect with a single theory to explain the origin of ball lightning? What are the limitations of observation on our imagination?

In 1966, NASA circulated a questionnaire among two thousand people, in the first part of which two questions were asked: "Have you seen ball lightning?" and "Have you seen a linear lightning strike in the immediate vicinity?" The answers made it possible to compare the frequency of observing ball lightning with the frequency of observing ordinary lightning. The result was stunning: 409 out of 2 thousand people saw a linear lightning strike at close range, and ball lightning - two times less. There was even a lucky one who met ball lightning 8 times - another indirect proof that this is not at all such a rare occurrence as is commonly thought.

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

There is such a lightning from a few seconds to a minute; can penetrate into rooms through small openings, then regaining its shape. Many observers report that it throws out some kind of sparks and rotates. She usually hovers a short distance from the ground, although she was also met in the clouds. Sometimes ball lightning quietly disappears, but sometimes it explodes, causing noticeable destruction.

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

Why does ball lightning glow?

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

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

The cause of ball lightning

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

Posted on Allbest.ru

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L frost lightning (cloud-earth)

How to get such a lightning? It's very simple - all that is required is a couple of hundred cubic kilometers of air, a height sufficient for the formation of lightning and a powerful heat engine - well, for example, the Earth. Ready? Now let's take air and gradually start heating it. When it begins to rise, then with each meter of rise, the heated air cools, gradually becoming colder and colder. Water condenses into larger and larger droplets, forming thunderclouds... Remember those dark clouds above the horizon, at the sight of which the birds become silent and the trees stop rustling? So, these are thunderclouds that give rise to lightning and thunder.

Scientists believe that lightning is formed as a result of the distribution of electrons in a cloud, usually positively charged from the top of the cloud, and negatively from. As a result, we get a very powerful capacitor, which can be discharged from time to time as a result of the abrupt transformation of ordinary air into plasma (this is due to the increasingly strong ionization of atmospheric layers close to thunderclouds). Plasma forms a kind of channels that, when connected to the ground, serve as an excellent conductor for electricity. Clouds are constantly discharging through these channels, and we see external manifestations of data. atmospheric phenomena in the form of lightning.

By the way, the air temperature at the place of passage of the charge (lightning) reaches 30 thousand degrees, and the speed of lightning propagation is 200 thousand kilometers per hour. In general, a few lightning bolts were enough to supply power to a small town for several months.

And there are such lightnings. They are formed as a result of the accumulating electrostatic charge on top of the tallest object on earth, which makes it very “attractive” for lightning. Such lightning is formed as a result of "breaking through" an air gap between the top of a charged object and the bottom of the thundercloud.

The taller the object, the more likely it is to be struck by lightning. So what they say is true - you shouldn't hide from the rain under tall trees.

Yes, lightning can "exchange" and individual clouds, striking each other with electric charges. It's simple - since the upper part of the cloud is positively charged, and the lower one is negative, nearby thunderclouds can shoot through each other with electric charges.

A fairly common occurrence is lightning breaking through one cloud, and much more rare occurrence is lightning that comes from one cloud to another.

This lightning does not strike the ground; it spreads horizontally across the sky. Sometimes such lightning can spread across a clear sky, proceeding from one thundercloud. Such lightning strikes are very powerful and very dangerous.

This lightning looks like several lightning bolts running parallel to each other. There is no mystery in their formation - if a strong wind blows, it can expand the channels from the plasma, which we wrote about above, and as a result, such a differentiated lightning is formed.

This is a very, very rare lightning, it exists, yes, but how it is formed is still anyone's guess. Scientists suggest that dashed lightning is formed as a result of the rapid cooling of some parts of the lightning track, which turns ordinary lightning into dashed lightning. As you can see, this explanation clearly needs to be improved and supplemented.

So far, we have only talked about what happens below the clouds, or at their level. But it turns out that some types of lightning are also higher than the clouds. They were known about them since the advent of jet aircraft, but these lightning bolts were photographed and filmed only in 1994. Most of all they look like jellyfish, right? The height of the formation of such lightning is about 100 kilometers. It is not yet very clear what they are.

Here is a photo and even a video of unique sprite lightning. Very beautiful.

Some people argue that there are no fireballs. Others post videos of fireballs on YouTube and prove that this is all a reality. In general, scientists are not yet firmly convinced of the existence of ball lightning, and the most famous proof of their reality is a photo taken by a Japanese student.

This, in principle, is not lightning, but simply the phenomenon of a glow discharge at the end of various sharp objects. The fires of St. Elmo were known in antiquity, now they are described in detail and captured on film.

These are very beautiful lightning bolts that appear during a volcanic eruption. Probably, a gas-dust charged dome, piercing several layers of the atmosphere at once, causes indignation, since it itself carries a rather significant charge. It all looks very beautiful, but creepy. Scientists do not yet know exactly why such lightning is formed, and there are several theories at once, one of which is stated above.

Here are a few interesting facts about lightning that is not published so often:

* A typical lightning bolt lasts about a quarter of a second and consists of 3-4 strokes.

* Average thunderstorm travels at a speed of 40 km per hour.

* There are 1,800 thunderstorms in the world right now.

* In the American Empire State Building, lightning strikes an average of 23 times a year.

* On average, lightning strikes airplanes once every 5,000-10,000 flight hours.

* The probability of being killed by lightning is 1 in 2,000,000. The same chances are for each of us to die from falling out of bed.

* The probability of seeing ball lightning at least once in a lifetime is 1 in 10,000.

* People who were struck by lightning were considered marked by God. And if they died, they supposedly went straight to heaven. In ancient times, victims of lightning were buried at the place of death.

What should be done when lightning is approaching?

In the House

* Close all windows and doors.
* Unplug all electrical appliances from electrical outlets. Do not touch them, including telephones, during a thunderstorm.
* Keep away from bathtubs, faucets and sinks as metal pipes can conduct electricity.
* If a ball lightning has flown into the room, try to get out quickly and close the door on the other side. If it fails, at least freeze in place.

Outside

* Try to get into your house or car. Do not touch metal parts in the machine. The car should not be parked under a tree: suddenly lightning strikes it and the tree falls right on you.
* If there is no shelter, go out into an open area and, bending over, press down on the ground. But you can't just go to bed!
* In the forest, it is better to hide under low bushes. NEVER stand under a freestanding tree.
* Avoid towers, fences, tall trees, telephone and electrical wires, bus stops.
* Stay away from bicycles, barbecues, and other metal objects.
* Keep away from lake, river or other bodies of water.
* Remove all metal from yourself.
* Do not stand in the crowd.
* If you are in an open area and suddenly feel that your hair is standing on end, or you hear a strange noise coming from objects (this means lightning is about to strike!), Bend forward with your hands on your knees (but not on the ground). The legs should be together, the heels are pressed together (if the legs are not in contact, the discharge will pass through the body).
* If a thunderstorm caught you in the boat and you do not have time to swim to the shore, bend down to the bottom of the boat, put your legs together and cover your head and ears.

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