Science

What is lightning?

Known for its beauty and power, lightning is a natural phenomenon that has always fascinated people. Without modern scientific equipment, ancient cultures used religion and mythology to provide an explanation for such a spectacular event. Today, more is understood about lightning, but there are still plenty of mysteries we've yet to unravel. So, what exactly is lightning?

Formation of thunderclouds

Dark thunderclouds forming in shapes over an empty green field
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Lightning is produced by special clouds called cumulonimbus clouds. These clouds are formed when warm air from the ground rises through the cooler air in a regular cumulus cloud. The warm air makes the cloud grow taller and taller until it looks like a dark, menacing tower that reaches way up into the sky.

Electrical buildup

Up close view of light bulb filament glowing with electric charge
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Water is an electrical conductor. As warm air rises up through the thundercloud, the water trapped in the air bumps into the water in the ice particles of the cloud. Anyone who has scuffed their socks across a carpet and touched a doorknob knows that when charged particles are rubbed together, static electricity is formed. As the warm, positively-charged air climbs higher and higher, more static electricity is built up within the cloud. Over billions of collisions, the electrical buildup becomes so great that the cloud can’t contain it anymore and it has to be released.

Lightning

Aerial view of bright lightning storm showing several bolts arcing to the ground
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When the static buildup is released, it’s released in a spectacular manner. A single bolt of lightning can contain up to a billion volts of electricity and heat the air around it to over 50,000 degrees Fahrenheit. That’s hotter than the surface of the sun!

Most lightning occurs within the cloud between the positive charge at the top and the negative charge at the bottom. Every now and then, depending on the strength of the electrical charge, lightning can escape the cloud and make its way to the ground.

Thunder

Aerial view of large cloud shaping in the air before a storm
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Lightning is so powerful that it superheats the area around the bolt — causing rapid expansion of the surrounding air. The air expands so quickly that it creates a shockwave accompanied by a loud boom. The stronger the shockwave, the longer the thunder rumbles.

Although thunder and lightning happen simultaneously, you’ll see the lightning before you hear thunder. Lightning travels at the speed of light, which is almost instantaneous for any two spots on Earth. Thunder travels at the speed of sound, which is about 1,000 feet per second depending on temperature and air density. So, to determine the distance of a thunderstorm, count the seconds between the time you see the lightning flash and hear the thunder. Every five seconds is approximately one mile. If you can count to 10 before you hear thunder, it means the storm is about two miles away.

Lightning strikes

Bright lightning bolt arcing through sky on a dark, cloudy night
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At any given moment, there are over 2,000 thunderstorms happening around the world. That's roughly 100 lightning strikes per second. Warm, humid places such as Africa and South America experience the most lightning strikes of any place on Earth. In the United States, Florida experiences the most lightning activity in the country.

Lake Maracaibo in Venezuela has the distinction of being the most lightning-friendly place in the world. The lake experiences 260 storm days per year with an average of 28 strikes per minute. People travel from all over to experience the unique phenomenon of the Catatumbo Lightning.

Being struck by lightning

Building roof in shambles after lightning strike and fire, seen on a clear bright day
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Although lightning strikes the ground 100 times per second worldwide, there’s a very low probability you will be struck. It’s estimated that there’s a one in 1.2 million chance of being hit by lightning in any given year.

Although it’s rare, it does happen. Luckily, despite the power of a lightning bolt, 90% of people who are struck by lightning survive the encounter. It just might not be the most pleasant experience of their lives.