Lightning

Glowing explosions produce shock waves of sound

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Lightning may have been an important puzzle piece in the origins of life, and the first people have probably taken fire from it. They must have experienced lightning as a gift from the gods, but today we know that thunder and lightning are natural processes that the researchers don't fully understand.

Storm has to do with the formation of rain clouds in unstable air. Such an unstable condition is often due to global warming, while higher air is cold.

Bubbles that are warmer than the surrounding air rise and form clouds. This reinforces the take-off even more. This process, called convection, is fairly common, especially around the equator and above large tracts of land.

Most lightning in Africa

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Of satellites that measure lightning discharges, meteorologists have learned a lot about the distribution of lightning strikes around the world. The researchers assume that around 40,000 thunderstorms occur on Earth every day. Most are created in regions around the equator. Here the heating by the sun is very powerful, as a result of which warm, moist air rises and forms large showers.

© Douglas E Walker / Getty Images

Convection is visible as dome-shaped, white cumulus clouds that expand upwards. At one point the cumulus cloud becomes a rain cloud that sometimes grows into a thunderstorm with a characteristic range of ice crystals at the top: called a cumulonimbus by meteorologists.

Whether a cumulonimbus causes thunderstorms or not is a matter of balance. A few hundred meters of extension at the top can make the difference.

Lightning bolts themselves are short and are intense electrical discharges, both in the clouds and between the clouds and the environment. Lightning can occur in the cloud itself, go from cloud to cloud, take place from cloud to sky or strike from the cloud on earth.

The voltage difference can be as high as hundreds of millions of volts and the current can reach 200,000 amperes when it flashes.

The total energy released in the lightning strike microseconds differs per lightning, but corresponds to about five 100-watt lights that burn for a month. Only a small part of the energy ends up where the lightning strikes, depending on the electrical resistance of the affected object.

Most of the energy ends up in the lightning channel between the cloud and the earth. The temperature in the lightning itself is around 15,000 to 30,000 ° C: five times as hot as the surface of the sun.

Bulb lightning and jets

There are more fables and stories about ball lightning than scientific articles. Because it is a fleeting and rare phenomenon, there are only a few pictures of it, and there is no accepted explanation of it yet.

A common theory is that sphere lightning consists of glowing plasma, held together by a magnetic field that is formed in the charged air. The stories tell almost all about spherical, luminous objects as large as a tennis to a football, which run around and finally disappear - possibly with a bang.

A fairly recently discovered type is the high or atmospheric lightning: red fairies, blue jets and elves. Red fairies are root-shaped discharges from the top of the clouds to a height of 90 kilometers. Blue jets are cone-shaped discharges that shoot up at high speed (up to 100 km / s = 360,000 km / h) from the thunderclouds up to around 40 km high.

Elves are luminous rings that extend in millions of seconds from the top of red fairies at a height of around 90 kilometers.

The sudden heating of the air around a bolt causes shock waves of sound: thunders. It rumbles because there is time between pressure waves from different locations in the lightning channel, and because the sound waves bounce between the clouds and the earth.

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Video: Making a Shockwave by Hitting Two Huge Steel Ball Bearings Together! (November 2019).

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