For a long time, people have been afraid of the natural phenomenon of lightning. In fact, the lightning we are talking about includes lightning and lightning. 1749, Franklin's kite experiment proved that lightning is only a spark discharge phenomenon in the atmosphere. Lightning is usually produced by cumulonimbus clouds and is often accompanied by thunder.
Lightning is a common natural phenomenon. Although they are common, some figures about lightning are interesting.
Usually, lightning will happen and end when people are unprepared. Therefore, lightning gives us a quick and violent impression.
The classic book Liu Tao Chang Tao Military Intelligence in the Warring States Period describes the lightning speed as follows: "Lightning is too fast to cover your ears, and lightning is too fast to print." This sentence is also the source of what we often say today: "Lightning cannot cover your ears". The source of the word.
From the perspective of contemporary science, it is lightning, not thunder, that is really "fast". The essence of thunder is a sound wave, and its propagation speed in the air is about 340 meters per second. The speed of lightning is far from this order of magnitude.
Scholars and experts have not come up with more accurate results about the specific value of lightning speed. Many people think that the speed of light is the speed of light, that is, 3 108m/s, but there are also many people who disagree and have a heated debate about it. So how fast is lightning? Is it the same as the speed of light
Taking cloud lightning as an example, the occurrence process of lightning is analyzed. According to the high-speed camera, a complete cloud-to-ground lightning is actually composed of several continuous discharge processes, which follow the same channel, like waves, wave after wave, and the time interval between two waves is only a fraction of a second. Each discharge generally includes two processes: the pilot process is mainly to establish the ionization channel of lightning discharge, which is equivalent to "paving the way"; When the ignition lightning is close to the ground, like a connecting wire, a powerful current flows from the ground to the clouds at an extremely fast speed. This process is called backhaul and takes about 70 microseconds. If there is enough electricity in the cloud, the second wire will return to discharge. A complete cloud-to-ground lightning process lasts about 0.2 seconds.
According to the above analysis, lightning is a discharge phenomenon and follows certain physical laws. Its moving speed is influenced by many factors, such as the conductivity of air, which is essentially different from the speed of light.
According to the research, the lightning speed is1105-1.4106m per second, and the average speed is 4.4105m per second.
Through several careful scientific observations of lightning, some scholars found that the speed of lightning at different stages is also different. For example, the average speed of lightning lead process is 1.5 105m/s, which is about 1/2000 of the light speed, while the speed of return stroke is much higher than that of lead, that is,11/of the light speed. The lightning speed of the US Department of Energy is1.5108m/s, which is about half the speed of light.
Although the above data may not be accurate, it is certain that the speed of lightning is much lower than the speed of light, and at the same time, it is much higher than the speed of light.
Many people think that the speed of lightning is the speed of light because lightning transmits the speed of light to our eyes and regards it as the moving speed of lightning itself.
When it comes to thunder, people may immediately think of words such as "deafening" and "earth-shattering". People often use thunder to describe strong and loud sounds, such as "thunderous applause" and "cheers". It can be said that thunder is one of the loudest sounds produced by nature.
So, how loud is the thunder?
When lightning happens, it releases a lot of light and heat. The air along the way is strongly heated, the water droplets evaporate rapidly, and the volume suddenly expands to produce shock waves, which makes the air vibrate violently. The sound made at this time is called "thunder". Thunder can reach 120 decibels. What is this concept? One decibel is the sound that people can only hear, and 40-60 decibels belong to the sound intensity of normal conversation. When the sound reaches 70 decibels, we think it is very noisy and begins to damage the auditory nerve. 100- 120 decibels is louder than the sound of a train whizzing by. If a normal person stays in such a high decibel space for more than 1 minute, you will be temporarily deaf. Therefore, it is not too much to describe thunder with "deafening".
How frequent is lightning activity on the earth? This is not only what we want to know, but also one of the key contents of lightning research. Over the years, many experts and scholars have used different methods and means to estimate the data, but the results are inconsistent.
In the study, the frequency of lightning is not only measured by the number of thunderstorm days, but also can be characterized by some data of lightning, such as lightning frequency (number) and lightning density. As early as 1925, some experts estimated the global lightning frequency by analyzing the data of thunderstorm days. It is generally believed that there are 1800 thunderstorms at any time in the world, and there are about 100 lightning every second.
In recent decades, the development of lightning detection technology, especially satellite lightning detection technology, has provided people with lightning observation data in areas that were difficult to be involved in ground observation in the past, thus making a more accurate estimate of this parameter: the global lightning frequency is about 40 50 times per second, and the annual lightning occurrence times are about 65.438+0.4 billion times. In the northern hemisphere, lightning is most likely to occur in summer, but in the equatorial region, lightning is more frequent in autumn and spring. Because there are few thunderstorms in the Arctic and Antarctic, there is almost no lightning there.
So, where is the most frequent lightning activity in the world?
According to this study, the most active area of lightning is the Congo Basin in Africa. Because it is close to the equator, the surface heat is sufficient, the air convection is frequent, and there are thunderstorms all the year round.
Relevant scholars have concluded that the most frequent lightning activity in the world is in Rwanda, Africa, where the maximum lightning density is 80 times per square kilometer every year. However, from 2004 to 2005, Kifka village, a small mountain village in eastern Congo, broke the above record and became the most frequent lightning spot in the world. The town is only 300 kilometers from the equator and 975 meters above sea level. The density of lightning is unprecedented. In a year, there are 158 lightning strikes per square kilometer.
The discharge process of lightning is very short, generally 50- 100 microsecond (1 microsecond equals 1 millionth of a second), which can be said to be instantaneous. The average pulse current is as high as 30,000 amps, and the maximum current can reach 300,000 amps. The induced voltage of the alternating magnetic field generated by this strong current can reach 1000- 100 billion volts. After the charge is neutralized, it will release a lot of light and heat, and immediately heat the surrounding air to 30 thousand degrees Celsius, which is five times the surface temperature of the sun.
The energy generated by a lightning strike is enough to drive an ordinary car for 290- 1450 km, which can provide the total electricity consumption of a family for nearly one year. Of course, although the electric power of lightning is large, the electric power of lightning current is not large because of the short discharge time.
Unfortunately, however, it is precisely because lightning often happens in an instant, and the direction of lightning is difficult to predict, so modern technology cannot collect and use the power of lightning.
Lightning can cause great damage in an instant because of its physical effects such as strong current, high temperature, strong electromagnetic radiation and violent shock wave. Once a person is hit by it, it will have fatal consequences.
More than 4000 people are struck by lightning every year in the world. On average, the probability of being struck by lightning is not high, which is about one in 1.75 million. However, we should not neglect lightning protection. Because specific to different regions, the probability of people being struck by lightning in each place is different. For example, the current per capita lightning strike probability in countries such as North America is one in 600,000.
According to relevant statistics, there are obvious differences between urban and rural lightning probability. Farmers have long worked in open areas such as farmland. When lightning struck, they lacked temporary shelter and the surrounding terrain was flat. Relatively speaking, the position of the human body may be higher. Farmers' knowledge of lightning protection is relatively lacking. When urban workers work indoors, the lightning protection measures of urban buildings are relatively perfect, and the probability of being struck by lightning is greatly reduced.
In addition, the probability of being struck by lightning is also related to gender. A study in the United States shows that men are more vulnerable to lightning strikes than women. This study analyzed the data of lightning death in North America and other countries from 1995 to 20 18, and found that 82% of the 648 deaths were male. Another study completed on 20 19 reached a similar conclusion. Why are men more vulnerable to lightning than women? The answer given by American meteorologists is that when thunderstorms occur, men often do some dangerous things in the rain, such as playing golf and playing football, while women prefer to stay in a safe place to avoid the rain.
In addition, the probability of residents being struck by lightning in a certain area is also related to local living habits, educational level and building structure.