What is Lightning?

Mary McMahon
Mary McMahon

Lightning is a discharge of atmospheric electricity that is triggered by a buildup of differing charges within a cloud. The result is a sudden release of energy that causes a distinctive bright flare, followed by a thunderclap. Lightning is most common around the equatorial regions of the world, although it can potentially strike anywhere, and it appears in a variety of guises, depending on atmospheric conditions.

Hail sometimes accompanies electrical storms.
Hail sometimes accompanies electrical storms.

There are several competing theories to explain why differing electrical charges appear in clouds, although scientists suspect that it may be related to the presence of ice crystals. Typically, the bottom of a cloud becomes negatively charged, and it sends out what is known as a “leader” that seeks a positive charge, either in another cloud or on the earth. As the leader approaches an area that is positively charged, a positively charged streamer emerges, meeting the leader, sealing the connection, and generating a bolt of lightning.

Positive lightning emanates from the ground and is extremely dangerous.
Positive lightning emanates from the ground and is extremely dangerous.

After the lightning travels to the ground or another cloud, it may strike again several times within a fraction of a second. These re-strikes are so fast that people cannot register them with the naked eye; instead, they appear as a single strike. The electricity moves so quickly that it superheats the surrounding air, causing a sudden rapid expansion that creates a shockwave. Shockwaves are responsible for thunder; because thunder is so closely associated with lightning, some people attempt to judge the distance of a storm by counting the time which elapses between a strike and a thunderclap.

Most lightning travels from cloud to cloud, or from a cloud to the ground. In rare circumstances, however, the charges will be reversed, and lightening will emanate from the ground. This is known as “positive lightning,” and it is rare and extremely dangerous. It is often triggered by human activities, such as the liftoff of a rocket or the detonation of a nuclear device.

Many people associate classically jagged streaks in the sky with lightning, but it can also appear in bursts known as bead lightning, or it can reflect from the clouds, making sheet lightning. Some people may also be familiar with ball lightning, an unusual manifestation that is rarely observed.

An individual who is caught outside during a thunderstorm and who cannot take shelter in a car or house should hunch his body close together, making himself a small target, with only his feet touching the ground. People who are indoors should stay away from phones and plumbing, as lightning can sometimes travel through phone wires or plumbing systems.

Those who cannot go inside during a lightning storm should hunch down close to the ground to avoid getting struck.
Those who cannot go inside during a lightning storm should hunch down close to the ground to avoid getting struck.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@seag47 – It's Florida. I think this is because the weather there is so humid and warm for the majority of the year. Being surrounded by the ocean plays into this, too.

I vacation at the ocean nearly every summer, and I've noticed that thunderstorms roll in off the ocean just about every day. You can bank on having an afternoon thunderstorm even if you don't get one in the morning.

This is why I do most of my beachcombing right after sunrise. I wait until later in the afternoon to go shopping and eating at restaurants, because I don't feel safe on the beach when I can actually see the lightning in the distance.

Many people don't seem threatened by it. They just stay out there, determined to enjoy as much of their vacation as possible, regardless of the danger.


My local weatherman likes to put up a map of the state that shows the number of lightning strikes in each area during a thunderstorm. There seem to be a lot more of these strikes concentrated in one area during the summer storms than during the winter ones.

I live in Mississippi, and I am amazed at how much thunder and lightning we get during the summer. Does anyone know what the state with the most lightning strikes is? I will be shocked if it isn't my state!


My dogs are very skilled at lightning detection. They start to act scared and hide in the closet before I can even hear thunder. Within a few minutes, it usually gets loud enough for me to hear it.

It's weird how some dogs are terrified of lightning and others couldn't care less about it. I've heard that it causes static electricity in their coats and this is what scares them, but if that's true, then how come all dogs aren't afraid?

Personally, I think it's the loud noise that terrifies them. If you heard something rumbling in the sky and you had no way of knowing what it was, wouldn't you be afraid?


Lightning struck the workshop in my backyard when I was young, and it shattered the concrete floor in one spot. After that, my dad decided to install some lightning protection.

He put a lightning rod on the roof. It was attached to something in the ground, so if lightning ever hit the building, it would travel down into the ground and not damage the shop.


Does lightning come from the earth up or from the sky down?


Some lightning comes from the ground up, but not all. There are four main types of lightning: cloud-to-ground, ground-to-cloud, intra-cloud, and inter-cloud.


What is lightning in general? Is it sparks of electrons or plasma?


actually lightening is caused by interaction of clouds elements on a large scale. this produces electric current in great excess and this heavy charge/current is at once transferred to the ground and lightning takes place.


I was told that lightning is an optical illusion and comes from the ground up. Do you know if this is true?


Lightning has a positive effect on the soil. Each time lightning strikes, it charges nitrogen into the soil, so in effect lightning can be viewed as a fertilizing agent.

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