Lightning

Lightning is a bright flash of light.

It happens when parts of the sky have different energy. This energy jumps between clouds or to the ground.

When lightning strikes the ground, it is called a strike.

This can be dangerous to people and things.

The flash is very hot. This heat makes the air move fast. This move makes a loud boom called thunder.

Lightning can happen in many ways. It can happen in a storm. It can even happen during a volcano eruption.

Some lightning can start a fire.

It is a powerful part of our world.

Lightning is a bright flash of light.

It happens when different parts of the sky have electric charges. These charges jump between two areas to balance out. This jump is called a discharge.

There are three main types of lightning. Intra-cloud lightning happens inside a single cloud. Cloud-to-cloud lightning happens between two different clouds. Cloud-to-ground lightning happens between a cloud and the earth. We call this a lightning strike.

These strikes can be dangerous to people and buildings.

Most strikes are negative. This means electrons flow down to the ground. Some strikes are positive. These are less common but much stronger. They can travel long distances through clear air. People sometimes call them "bolts from the blue."

Positive lightning is very powerful. It can heat surfaces and start forest fires.

Lightning also makes thunder. The flash heats the air very quickly. This heat makes the air expand with a sudden increase in pressure. That sudden move creates a loud sound wave.

Lightning is a sudden flash of light in the sky. It happens when electricity jumps between two areas that have different electric charges. This jump is called an electrostatic discharge.

One area might be inside a cloud, while the other is on the ground. This process releases a huge amount of energy very quickly. A single flash can release between 200 megajoules and 7 gigajoules of energy.

This energy heats the air around it to very high temperatures. This heat creates a shock wave that we hear as thunder.

There are three main ways lightning works. Intra-cloud lightning happens inside just one single cloud.

Cloud-to-cloud lightning happens between two different clouds. The third type is cloud-to-ground lightning, which we call a lightning strike.

To make a strike, a stepped leader moves down from the cloud. At the same time, a streamer moves up from the ground. When these two meet, they create a bright flash. Most of these strikes are negative, meaning electrons flow down to the earth.

Scientists study lightning using a field called fulminology.

They have learned that positive lightning is different from negative lightning. Positive lightning is much less common, making up less than 5% of all strikes. However, these strikes are much more powerful and dangerous. A negative bolt might have a current of 30,000 amperes. A large positive bolt can reach 120,000 amperes or even more.

These powerful bolts can travel through clear air. This is why people call them "bolts from the blue."

Lightning does not only happen in normal thunderstorms. It can happen during volcanic eruptions or even in dust storms.

Intense forest fires can even create their own weather systems. These fires cause hot air to rise and form special clouds called pyrocumulonimbus clouds. These clouds can produce dry lightning, which can start even more fires. Lightning also happens in the winter during a storm called thundersnow.

Even rockets can cause lightning when they take off. The exhaust from a rocket can provide a path for the electricity to follow.

Understanding lightning helps us stay safe during big storms. It also helps us understand how our planet's atmosphere works. Lightning is an Essential Climate Variable for the World Meteorological Organization. This means it is a very important part of studying our weather.

You might see lightning from a distance at night. This is often called "sheet lightning" when it stays in the clouds. Even if you do not hear thunder, the light tells a story about the energy moving through our sky.

Lightning is a natural phenomenon consisting of electrostatic discharges. These discharges occur through the atmosphere between two electrically charged regions. One region may be located within the atmosphere, while the second region sometimes occurs on the ground. When lightning occurs, the two regions become partially or wholly electrically neutralized. This process involves a near-instantaneous release of energy. On average, a single flash releases between 200 megajoules and 7 gigajoules of energy.

The mechanism of lightning begins with charge separation. This often happens when warm air mixes with colder air masses. This mixing creates atmospheric disturbances that polarize the atmosphere. These disturbances result in storms, such as thunderstorms. Lightning also occurs in other energetic systems like volcanic eruptions or dust storms.

During a discharge, the air around the flash rapidly heats to extreme temperatures. This rapid heating causes the gases in the vicinity to experience a sudden increase in pressure. This pressure change creates a shock wave that we hear as thunder.

Scientists categorize lightning into three primary forms based on where they occur. Intra-cloud (IC) lightning happens within a single thundercloud. This is the most frequent type of lightning. Cloud-to-cloud (CC) lightning occurs between two separate clouds.

The third type is cloud-to-ground (CG) lightning, which is commonly called a lightning strike. While IC and CC lightning are more common, CG lightning poses the greatest threat to life and property. It terminates on a physical object on the ground.

Cloud-to-ground lightning follows a specific sequence of steps. It is initiated by a stepped leader moving down from the cloud. This leader is met by a streamer moving up from the ground. The overall discharge, or flash, involves several processes. These include preliminary breakdown, connecting leaders, and return strokes. The conductivity of the ground can also affect the discharge. This depends on whether the surface is soil, fresh water, or salt water.

Researchers distinguish between positive and negative lightning strikes. Most CG lightning is negative, meaning electrons flow downward to the ground. In a positive CG flash, electrons travel upward while a positive charge moves downward. Positive lightning is less common, making up less than 5% of all strikes. However, positive strikes are much more intense. An average negative bolt creates a current of 30,000 amperes. In contrast, large positive bolts can create up to 120 kA.

Positive lightning is significantly more dangerous than negative lightning. It produces higher peak currents and longer continuing currents. These factors allow the lightning to heat surfaces to much higher levels. This increased heat raises the likelihood of igniting a fire. Positive lightning can also propagate through clear air. This characteristic leads to the term "bolts from the blue." These strikes can occur during winter storms, known as thundersnow, or during intense tornadoes.

Lightning can also be triggered by human technology or extreme natural events. Intense forest fires can create pyrocumulonimbus clouds. These clouds are formed by rapidly rising hot air within a smoke plume. These systems can produce dry lightning, which may cause further forest fires. Even rocket exhaust plumes have been observed to provide a pathway for lightning. During the Apollo 12 takeoff, lightning was witnessed striking the rocket.

The study of lightning is a scientific field called fulminology. The World Meteorological Organization considers lightning an Essential Climate Variable. This means it is vital for understanding the global atmospheric electrical circuit. Lightning also influences atmospheric chemistry. By studying these discharges, scientists gain a deeper understanding of how energy moves through our planet's atmosphere.