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The Mystery of Thunder and Lightning

2018-09-26  |   Editor : houguangbing  

Why is it windy before a thunderstorm pours?

Everyone knows that a thunderstorm is usually preceded by a gust of wind and followed by pouring rain, which is more common in mountainous areas. Why is it windy before a thunderstorm pours?

The reason is that during summer, the air near the ground heats up dramatically and the warm and humid air is particularly powerful under the influence of favorable weather systems. Especially when the horizontal air is blocked by mountains and uplands, on the one hand, the lifting power from the terrain raises up the warm and humid air along the hillside; on the other hand, the heat from the mountains also expand the air near the stratum, making it rise and easily form thunder clouds. As a result, there are both strong updrafts and downdrafts inside thunder clouds.

When the cold air from the thunder cloud reaches the ground, it quickly spreads around, forming a heap of cold air. Due to the density of the sinking cold air, the pressure of the cold air heap rises rapidly, resulting in the cold anticyclone, known as the thunderstorm high.

In this way, wind starts blowing as a result of the large difference in pressure in the small area. When the wind pours from the center of the thunderstorm high, it will accelerate abruptly, generally up to more than 10 meters per second, and sometimes up to 30 meters per second.

Thunderstorms arrive soon after the gusts, followed by low pressure that produces precipitation. That’s why winds tend to precede thunderstorms.

However, not all thunderstorms are preceded by strong winds. Sometimes fierce winds and thunderstorms strike at the same time. Sometimes the sky is filled with thunder clouds, but there is only rain without wind. This is because for some certain thunderstorms, due to their specific time, location and conditions, and some characteristics of its own, there are exceptions.

The Mystery of the Flashing and Rumbling of Thunder and Lightning

Why do we always see lightning before we hear thunder while the lightening and rumbling sound actually happen at the same time? This is because light travels much faster than sound. Light travels 300, 000 kilometers per second in the air, and at this speed it can travel seven and a half times around the earth's equator in one second. Sound travels about 340 meters per second through the air, about one-ninth of the speed of light.

It takes only a few millionths of a second for light to reach the ground from where lightning strikes, and longer for sound to travel the same distance. Sometimes lightning doesn't meet thunder, either because the clouds are too far away from us, or because the sound is not loud enough. Because as sound travels through the air, its energy gets weakened, and eventually it becomes inaudible.

There is a flash of lightning in the sky, there will a clap of thunder, but sometimes we see a flash of lightning with continuous thunder. And the sound lasts for a long time. This is because generally the lightning in the sky is very long. Some linear lightning is as long as 2000 meters to 3000 meters, even 10,000 meters or so.

On one hand, each part of the lightning is differently far from us, so the time for the thunder to reach us also varies. Lightning, on the other hand, does not usually stop after occurring once. It usually flashes several times in succession in a second.

In addition, when thunder hits the ground, buildings, mountains or clouds in the sky, it will reflect and generate echoes. As these echoes reach our ears one by one, the "rumble" of thunder happens. Sometimes, for several reasons, the peal of thunder can go on for a minute or so.

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