27/07/2010
Scientists have been studying lightning for hundreds of years. Although they know perfectly well what causes lightning, these mysterious flashes of electricity hold many more secrets.
At reading that the holiday season has begun in the summer, we suggest that you replenish your knowledge box with useful and interesting facts about lightning. Let's consider how true some myths about lightning are.
Myth: tornadoes and hurricanes are more dangerous than lightning.
Fact: lightning kills more people each year than tornadoes or hurricanes. More people die from floods than from lightning.
Myth: even at home you can be struck by lightning.
Fact: Perhaps the safest place during a thunderstorm is inside the house, but that doesn't mean you shouldn't take precautions.
If lightning strikes a building, electricity most likely will pass through the plumbing or wiring before going into the ground. Therefore, during lightning, do not talk on a wired telephone, stay away from running water (do not take a shower, do not wash dishes and hands). Do not use a cooker, computer or other appliances connected to the mains.
Myth: lightning always brings down planes.
Fact: in reality, lightning strikes planes regularly, but rarely causes them to crash. On average, every aircraft is struck by lightning at least once a year. Most airplanes are made of aluminum, which is a good conductor of electricity, so there are strict safety regulations for airplanes.
Myth: During thunderstorms, turn off electronic devices.
Fact: current surge can damage electronics, even if lightning does not hit your home. If you are unsure of the operation of the surge protector, turn off your computer, TV, and other electronics. If you start turning off appliances during a thunderstorm, there is a chance of electric shock, so this should be done before the thunderstorm starts.
Myth: during a thunderstorm it is dangerous to be in the car.
Fact: in fact, cars are one of the safest places during a thunderstorm if you can't get into a building. Just make sure your car has a secure and strong roof: a golf cart or convertible won't work.
Myth: lightning does not strike twice in the same place.
Fact: during a thunderstorm, lightning can strike the same place several times.
Myth: It is not safe to be outside during a thunderstorm.
Fact: If you are outside during a thunderstorm, try to take shelter in a grounded building or in a car. If this is not possible, then the following tips will help minimize the risk: avoid open spaces and tall objects (such as trees) standing alone. Stay away from water - it conducts electricity well. Do not lie down on the ground - this will increase the contact area, because if lightning strikes the ground not far from you, then what less area contact, the less current will flow into you.
Myth: It is necessary to stay at home for another half an hour after the end of the thunderstorm.
Fact: in most cases, lightning strikes people not in the midst of a thunderstorm. According to the US National Weather Service (NMS), lightning can strike from 15 km away from where it rains, so if you hear thunder, you are in a lightning threat zone.
The NMS advises to adhere to the following advice: “If you hear thunder, then wait at home. It will be safe to leave the house half an hour after the last thunder rumbled.
Myth: You can determine the distance to a thunderstorm by counting how many seconds passed from the flash of light to the thunder.
Fact: Surprisingly, this childish trick really works. Light travels faster than sound, so we first see a flash of light and then a roll of thunder.
To determine the distance to a thunderstorm, you need to know the speed of sound: it moves at a speed of 1 km in 3 seconds .
In the section on the question How can I measure the distance to a thunderstorm? given by the author Aggressive noob the best answer is the distance to a thunderstorm can be determined by the time between a flash of lightning and a roll of thunder (1s - distance 300-400 m, 2s - 600-800 m, 3s - 1000 m)
Answer from Ekaterina Kurzeneva[guru]
For some reason, my parents explained to me this way: Count the seconds between the flash of lightning and the first clap of thunder. 1s-1 km.
Answer from Vasisualy Levaterenolovich[guru]
It was found that the speed of sound is 171 toise per second, which corresponds to 337 m / s. Therefore, 3 sec ~ kilometer
Answer from Serrrega[guru]
No.. I'm not against physics.. .But.. I want to put in my twenty cents... .Maybe I'm wrong. . But a thunderstorm does not COMING from one point... This is generally a global phenomenon... And counting the seconds between the appearance of lightning and thunder is incorrect, you'll excuse me... I observed thunderstorms when lightning was present for three seconds in the form of a flash within a radius of 180 degrees.. (left-right-front). And the thunder rumbled. then .... peal and stereo ... Your subwoofers and stereo effects are resting ... And how is it???? This is Moscow suburbs... I don't go far... I saw lightning but didn't hear thunder.. I heard thunder.. But I didn't see lightning.. How is that? How is it with D. Granin? "I'm going to the storm" 🙂
Answer from B and x r b[guru]
Hello!
Everything is pretty simple. Turn on the stopwatch at the moment of the lightning flash, and turn it off when the sonic boom begins. Multiply the number of seconds by 340 (cf. the speed in m/s of sound) and get the distance to the lightning in meters! If you make several such observations in a row and write down the results, you can calculate whether a thunderstorm is approaching you or moving away from you, and even at what speed it happens!
But at the same time, you need to keep in mind that lightning can be several kilometers long (see photo) and therefore the sound comes to you with a time shift from different parts lightning, and therefore the thunder begins to "grumble" as the sound approaches from more distant sections of the lightning. At the same time, close lightning gives a higher-frequency sound, and distant lightning gives a low-frequency sound, since at large distances the high frequencies of the sound "extinguish", and long-wave low-frequency ones penetrate long distances, which is why only low-frequency "grunts" come from distant lightning.
I am enclosing a photo of the lightning, which, according to the calculations of its parameters, showed that the thickness of the lightning rod was about 50 m!
All the best.
Instruction
Lightning is dangerous to human life. However, ironically, it is through the fault of people that there are more and more of them. This happens due to an extremely irresponsible attitude to the environment: ambient air pollution in megacities increases the heating of the air and the rise of steam-condensate into the atmosphere. This amplifies the electrical intensity in the clouds and provokes lightning discharges.
The need to determine the distance to lightning is caused not only by the need to expand one's horizons, but also by the elementary instinct of self-preservation. If it is too close, and you are in an open space, then it is better to run away from there as soon as possible. Electric current chooses the most shortcut to the ground, and the skin is an excellent conductor for it.
Start counting seconds as soon as you see a flash of light in the sky, use a clock or a stopwatch. As soon as the first roll of thunder is heard, stop counting, so you will get time.
To find the distance, you need to multiply the time by the speed. If accuracy is not very important for you, then it can be taken equal to 0.33 km / s, i.e. multiply the number of seconds by 1/3. For example, according to your calculations, the time to lightning was 12 seconds, after dividing by 3 you get 4 km.
To determine the distance to lightning more accurately, take average speed in the air equal to 0.344 km/s. Its true value depends on many factors: humidity, temperature, type of terrain (open space, forest, urban high-rise buildings, water surface), wind speed, etc. For example, in rainy autumn weather, the speed of sound is approximately 0.338 km / s, in dry summer heat - about 0.35 km / s.
dense forest and high buildings significantly slow down the speed of sound. It decreases due to the need to go around numerous obstacles, diffraction. It is quite difficult to make an accurate calculation in this case, and most importantly, it is not advisable: despite the fact that lightning will not strike the ground, it can hit a tall tree next to you. So wait it out between low-growing trees with a dense crown, best of all on your haunches, and if you are on a city street, then take cover in a neighboring building.
Notice the wind. If it is strong enough and blows in your direction away from the lightning, then the sound is coming faster. Then its average speed can be taken approximately equal to 0.36 km/h. When the direction of the wind is from you to the lightning, the movement of sound, on the contrary, slows down and the speed is approximately equal to 0.325 km/h.
The average length of lightning reaches 2.5 km, and the discharge extends over a distance of up to 20 km. Therefore, you should leave the open place as soon as possible in the nearest building or structure. Remember that when lightning approaches, you need to close all windows and doors and turn off electrical appliances, as damage can occur through the antenna and through the network and harm your equipment.
Lightnings are not only terrestrial, but also intra-cloud. They are not dangerous to those on the ground, but they can damage flying objects: airplanes, helicopters and other vehicles. In addition, a metal object caught in a cloud with a strong electric field, capable of supporting, but not creating a charge, can become the initiator of lightning and provoke its appearance.
In the warm season, thunderstorms are quite common - impressive natural phenomena, however, causing not only curiosity, but also fear. During a thunderstorm, electric discharges occur between the clouds and the Earth, which are clearly visible and audible: lightning is observed in the form of branching luminous lines penetrating the sky, and a little later we hear the rolling sound of thunder. In this case, as a rule, there is a heavy rain, accompanied by heavy winds and hail. A thunderstorm is one of the most dangerous atmospheric phenomena: only floods are associated with a greater number of human casualties than thunderstorms. Interest in the study of natural electricity arose in ancient times. The first to investigate the electrical nature of lightning was Benjamin Franklin, an American political figure but also a scientist and inventor. It was he who, back in 1752, proposed the first draft of a lightning rod. Let's try to figure out what kind of danger a thunderstorm carries, and what you need to know and do in order to protect yourself.
At the same time, about one and a half thousand thunderstorms operate on Earth, the average intensity of the discharges is estimated at 100 lightning per second, or over 8 million per day. Thunderstorms are unevenly distributed over the surface of the planet. There are approximately ten times less thunderstorms over the ocean than over the continents. About 78% of all lightning discharges are concentrated in the tropical and equatorial zone (from 30° north latitude to 30° south latitude). Thunderstorm activity peaks at Central Africa. There are practically no thunderstorms in the polar regions of the Arctic and Antarctic and over the poles. The intensity of thunderstorms follows the sun: the maximum thunderstorms occur in the summer (in the middle latitudes) and in the daytime afternoon hours. The minimum recorded thunderstorms occur before sunrise. Thunderstorms are also affected by geographical features of the area: strong thunderstorm centers are located in the mountainous regions of the Himalayas and the Cordillera.
During a thunderstorm, a huge voltage arises between the clouds and the Earth, reaching a value of 1000000000 V. At this voltage, the air is ionized, turning into plasma, and a giant electric discharge occurs with a current strength of up to 300,000 A. The temperature of the plasma in lightning exceeds 10,000 ° C. Lightning is manifested by a bright flash of light and a shock sound wave, which is heard a little later as thunder. Lightning is also dangerous because it can strike completely unexpectedly, and its path can be unpredictable. However, the distance to the storm front and the speed of its approach or removal can be easily determined using a stopwatch. To do this, it is necessary to detect the time between the flash of lightning and the roll of thunder. The speed of sound in air is about 340 m/s, so if you hear thunder 10 seconds after the flash of light, then the thunderhead is about 3.4 km away. By measuring in this way the time between a flash of light and thunder, as well as the time between different lightning strikes, one can determine not only the distance to them, but also the speed of approach or removal of a thunderstorm front:
where is the speed of sound, is the time between the flash of light and the thunder of the first lightning, is the time between the flash of light and the thunder of the second lightning, is the time between lightning. If the velocity value is positive, then the storm front is approaching, and if it is negative, it is moving away. It should be taken into account that the direction of the wind does not always coincide with the direction of the thunderstorm.
If, nevertheless, you are caught in a thunderstorm, then you should follow a series simple rules to be safe:
First of all, during a thunderstorm, it is advisable to avoid open areas. Lightning is more likely to hit the highest point, a lone person in a field is that very point. If for some reason you are left alone in the field with a thunderstorm, hide in any possible recess: a groove, a hollow or the lowest place in the field, squat down and keep your head down. It should be remembered that sandy and stone soils have lower electrical conductivity, which means they are safer than clay soils. You should not hide under free-standing trees, as they are primarily susceptible to lightning strikes. And if you are in the forest, then it is best to hide under undersized trees with a dense crown.
Secondly, avoid water during thunderstorms as natural water- a good current conductor. The lightning strike spreads around the reservoir within a radius of about 100 meters. Often she hits the shore. Therefore, during a thunderstorm, it is necessary to move away from the coast, while swimming and fishing are not allowed. In addition, during a thunderstorm it is desirable to get rid of metal objects. Watches, chains, and even an umbrella opened over your head are potential targets for a strike. There are known cases of lightning strikes on a bunch of keys in your pocket.
Thirdly If a thunderstorm caught you in a car, then it protects you quite well from lightning, since even when lightning strikes, the discharge goes through the surface of the metal. Therefore, close the windows, turn off the radio and GPS-navigator. Do not touch any metal parts of the vehicle. It is very dangerous to speak during a thunderstorm. mobile phone. It is best to turn it off during a thunderstorm too. There were cases when an incoming call caused a lightning strike. A bicycle and a motorcycle, unlike a car, will not save you from a thunderstorm. It is necessary to get down, lay the transport on the ground and move at a distance of about 30 m from it.
In nature, there are different types of lightning: linear (ground, intra-cloud, lightning in the upper atmosphere) and ball lightning - luminous formations floating in the air, uniquely rare a natural phenomenon. If the nature of linear lightning is clear and its behavior is more predictable, then the nature of ball lightning still holds many secrets. Despite the fact that the probability of hitting a person with ball lightning is small, nevertheless, it poses a serious danger, since there are no reliable methods and rules for protecting against it.
The behavior of ball lightning is unpredictable. It can suddenly appear anywhere, including indoors. There have been cases of the appearance of ball lightning from a telephone receiver, an electric razor, a switch, a socket, a loudspeaker. Quite often, it penetrates buildings through pipes, open windows and doors. Cases are known when fireball penetrated into the room through narrow cracks and even a keyhole. The size of ball lightning can be different: from a few centimeters to several meters. In most cases, ball lightning easily floats or rolls above the ground, sometimes jumping, but it can also hang above the ground. According to eyewitnesses, ball lightning reacts to wind, draft, ascending and descending air currents. But this is not always the case: there are cases when ball lightning did not react in any way to air currents.
Ball lightning can suddenly appear and just as suddenly disappear without harming a person or a room. For example, it can fly into the window and fly out of the room through open door or a chimney flying past you. At the same time, you should be aware that any contact with a person leads to serious injuries, burns, and in most cases to death. Therefore, if you see ball lightning, it is safest to move away from it as far as possible.
In addition, ball lightning often explodes. The resulting air shock wave can injure a person or lead to destruction. For example, there are known cases of lightning explosions in stoves, chimneys, which led to serious damage. The temperature inside ball lightning reaches 5000 ° C, so it can cause a fire. The statistics of the behavior of ball lightning suggests that in 80% of cases the explosions were not dangerous, but serious consequences still occurred in 10% of the explosions.
According to the proposed method, we suggest that you calculate the distance to the lightning discharge and its speed if the first thunder was heard 20 seconds after the observation of the first lightning, and the second 15 seconds after the observation of the second lightning. The time between lightnings is 1 minute.