Questions and Answers about Lightning


Lightning Science is not a site about lightning!

Our purpose at Lightning Science is to build a community to educate and advocate for science. We use science to reach, engage and educate people, making the world a smarter, more livable place.

But since you’ve found this page, we’ll answer a few questions about lightning!

What is lightning?
Lightning is an electrical discharge between the ground and a storm cloud, or within a cloud.
Does lightning travel from the clouds to the ground, or the ground to the clouds?
Lightning travels from a negatively charged location to a positively charged location. This usually means that it travels from the ground upward into a storm cloud (though it’s too fast to see the direction of travel). But sometimes lightning can travel downward, or even between two places within the clouds.
What is thunder?
The energy of a lightning strike heats the air that it passes through, causing the air to expand and produce a shock wave, resulting in the sound that we call thunder.
Why does thunder follow lightning?
The image of the lightning strike travels to us at the speed of light (about 186,000 miles per second), while sound travels at just 1,200 feet per second, so the sound of thunder takes much longer to reach us than the light from the lightning strike.
How can I tell how far away the lightning struck?
When you see a flash of lightning, count the seconds until the sound of thunder reaches you. For each five seconds, the lightning is about 1 mile away.
How powerful is lightning?
It varies, but lightning can range from 10 million to 100 million volts, at an average of 30,000 amps. The temperature within a lightning strike can be more than 50,000 degrees Fahrenheit (five times hotter than the surface of the sun).
Could we harness lightning to produce electrical power?
That’s a great question! Unfortunately, although a lightning strike is very powerful, it only lasts 10 to 50 milliseconds. The TOTAL energy in the strike would power a single lightbulb for a few months, so it’s not really a practical source of power.
It looks like a lightning strike lasts much longer than 50 milliseconds!
Yes it does. The extremely bright flash causes you to see an after image which may last a second or more.
How many people are struck by lightning each year?
Each year in the United States an estimated 300 to 500 people are struck by lightning, and about 50 are killed.
How can I avoid being struck by lightning?
The best way to avoid being struck by lightning is to get indoors at the first sign of a thunderstorm. Stay away from plumbing fixtures or electrical devices, since a lightning strike call “follow” pipes or wires.  Do not take a bath or shower while there is a thunderstorm in progress.

A car can be a good shelter, but don’t touch the doors, roof, or body of the car. If the car is struck, the car’s body will carry the electrical energy around you to the ground.

If you are caught outdoors, stay away from “tall” things. For example, don’t take shelter under a lone tree, or under the tallest tree is a group of trees. If you are caught in the open, find a ditch to crouch in, or crouch down low as possible in the open.  Do not lie down, because the electricity from a lightning strike spreads along the surface of the ground.

If you are swimming, got out of the water!

Is it safe to touch someone who has been hit by lighting?
Yes.  The person’s body does not hold any residual electrical charge, so you can assist him or her just as you would any other injured person.


Further Reading


Lightning: Expert Q&A, NOVA, October 21, 2005.

Lightning Safety, National Oceanic and Atmospheric Administration (National Weather Service).

Frequently Asked Questions about Lightning Strikes, Center for Disease Control.

How Much Power is in a Bolt of Lightning?, Windpower Engineering and Development, August 20, 2013.


About Author

Lightning Science founder Robert Nicholson is a serial Internet entrepreneur with a passion for using science to improve life on earth.

He is also the founder of the ED Treatment Information Center, and an instructor in Computer Engineering at San Jose State University.

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