Why does lightning strike for less than a second and thunder lasts for several seconds?

The main reason is the difference between the speed of sound and the speed of light. When lightning occurs, the location of the lightning strike is due to the thermal effect of the compressed air to produce a supersonic shock wave that spreads in all directions, and then decays into sound waves. The direction is still in all directions.

Suppose lightning occurs at point A, and you are at point B, if the distance from A to B is 1km, and the simplified speed of sound is 333m s, then the time of propagation in a straight line in the middle is 3s. That is, 3s after the lightning happens, you will hear the first thunder. In the other direction, a certain component of the sound wave travels from the lowest path to your ears.

Suppose the propagation distance is 2km, then the time to your ears is the direction above 6s, assuming that it is, then the time to the ears is the above 3 components of the direction of the sound wave (a bit similar to the property of mathematical calculus), and the direction of the sound wave is continuous, because there are in all directions, so there will be thunder in all directions and at various distances. The distance is different and the speed is the same, so it will continue for a long, long time. Moreover, if the lightning strike point is far enough away from you, the sound wave will continue to attenuate, the wavelength will be stretched for a very long time, and the sound will become muffled and longer.

While the speed of light is about 3x10 8m s, the propagation time is negligible in either direction. Moreover, the streamer of lightning usually only lasts, so the light we see is only instantaneous. <>

Light and sound are both wave propagation, but the senses are different. can be expressed in equations. The difference is that the vibrations of sound waves are perceived by our ears, while light is observed by the human eye.

From the perspective of the vibration source, the scale is similar, the frequency is very different, and the propagation speed is very different, so there is no need to explain the disappearance of light. The propagation of sound waves is caused by the vibration of the air, and as long as the vibration is not possible to dissipate instantaneously, that is, if the medium at each point in the propagation path must be expressed by displacement and time, then it is an expression of the superposition of the sine and cosine functions. If the energy near the excitation point is large and the amplitude is large, and it propagates into space in the form of sound waves, and if we do not count the superposition of the reflection of the waves, we hear the sound vibrations near the ear.

And the vibration of each point is a function of time, so that nature does not hear a sound that disappears all at once... In fact, the sound heard is quite complicated. Because there is a medium of air and the earth, waves also have surface waves, longitudinal waves, transverse waves, etc.

If you are not a kinetics major, you can't list equations. <>

You can still fight! Thunder and lightning are constantly convection.

Theoretically, if you hear thunder within 30 seconds after seeing lightning, it means that you are in a danger zone, it's just a matter of probability, don't bet, just hide.

Related Notes:

Usually storm clouds (cumulonimbus clouds) produce electric charges, with yin electricity at the bottom and yang electricity at the top, and also a positive charge on the ground, which follows the clouds like a shadow. Positive and negative charges attract each other, but air is not a good conductor.

Positive charges run toward trees, hills, the tops of tall buildings, and even on top of the human body, in an attempt to meet negatively charged clouds; The negatively charged branch-like antennae extend downwards and get closer to the ground as they go downward. Finally, the positive and negative charges finally overcome the air barrier and connect. A huge electric current surged from the ground to the clouds along a conductive airway, producing a bright and dazzling flash.

The length of a lightning bolt may be only a few hundred meters (the shortest is 100 meters), but it can be several kilometers long. The temperature of lightning varies from 17,000 degrees Celsius to 28,000 degrees Celsius, which is equal to 3.5 times the surface temperature of the sun. The extreme heat of the lightning caused the air to expand violently along its path.

The air moves quickly, so waves are formed and sound is made.

Due to the very fast speed of light (3000000000 m s), you can basically see just lightning, even if lightning is on the moon you can see it in 1 second (if there is lightning on the moon and you can see it =. = So the question can be approximated as how many seconds it takes for you to hear the thunder travel to your ears. The speed of sound in the air is about 340m s, so if the place of thunder is 1km away from you, then lightning is about 3 seconds faster than thunder.

3000000 meters. According to the analysis, the speed of lightning per second is 300,000 meters per second, and to calculate how far the thunder will be after 10 seconds, you need to multiply 300,000 by 10 to get 3,000,000 meters, which is the correct answer.

The speed of light is much faster than the speed of sound, and the time difference between the two is as high as the time difference between human recognition.

Lightning and thunder are the result of static electricity interacting in the clouds in the sky. When the positive and negative electricity collide in the clouds, it not only emits a strong and dazzling electric light, but also emits a loud sound, which is what we call thunder. Scientists have measured that the transmission speed of electric light is 300,000 kilometers per second, and the transmission speed of sound in the air is only 340 meters per second, a difference of 880,000 times.

Therefore, when thunder and rain, it is always the electric light of lightning that reaches our eyes first, and then the sound reaches our ears. When the lightning is not far away from us, the difference is not very large, and if the lightning is far away from us, then it will be some time before we can hear the thunder.

In the summer, we often encounter thunderstorms, do you ever pay attention to always see lightning first, then hear thunder, you may think that lightning first and then thunder; It may also be thought that the place of thunder is far away from us, and the place of lightning is close to us. Actually, this is not the case, let's first take a look at how lightning is generated. Lightning and thunder are a phenomenon in nature.

The clouds in the sky are charged due to the irradiation of sunlight and friction and induction, and when the clouds with two different charges approach, the phenomenon of discharge will occur, and it will also emit flashes and ** sounds, which is the thunder and lightning in the air. It can be seen that lightning and thunder occur at the same time and in the same place, the flash of lightning is transmitted in the air at a speed of 300 million meters per second, the speed of lightning is only 340 meters in the air, and the speed of light in the air is about 882353 times the speed of sound, and the light is much faster than the propagation of sound. According to SV, although lightning and thunder occur at the same time, we always see lightning and then hear thunder.

At the same distance, light travels faster than sound.

Brain teaser: The eyes grow in front of the ears.

Common Sense: Light travels faster than sound.