What is Thunder and Lightning? Learn Some Interesting Facts and Safety Tips

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Updated on: Educator Review By: Michelle Connolly

Do you know what thunder and lightning is? Have you ever got frightened by the thunder sound? Do you know that you should follow specific tips during lightning times in order to stay safe and protect yourself? In this lesson, you are going to learn all about thunder and lightning as well as some safety tips to follow during lightning times. Let’s learn! 

What are Thunder and Lightning?

Lightning is a bright flash of electricity that appears in the sky during a thunderstorm. Thunder is the loud sound that is caused by the lightning. 


A thunderstorm is a storm that makes strong winds, heavy rain, lightning and thunder. A thunderstorm is produced by cumulonimbus clouds. The word “cumulonimbus” is Latin, and it is divided into two parts: “cumulus” which means pile, and “nimbus” which means rain cloud. Cumulonimbus clouds are a type of clouds that are large, tall and dark on the bottom. They form on hot days when warm, moist air rises high in the sky. These clouds usually produce gusty winds and rain.

A thunderstorm occurs when the air is unstable because of the collision between warm air and cold air. Warm air is lighter than cold air. On hot days, warm air rises up quickly and clashes with the cold air that is found high in the sky causing a thunderstorm.

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Types of Thunderstorms

1. Single-Cell Thunderstorms

They are small, weak storms usually found in spring and summer. They form, grow and die within an hour or so. Single-Cell thunderstorms can bring brief heavy rain, hail and sometimes lightning. 

2. Multi-Cell Thunderstorms

A multi-cell thunderstorm is the combination of multiple single-cell storms. It can bring hail and gusty winds, but it often leads to flash flooding. 

3. Squall Line Thunderstorms

A squall line is a line of thunderstorms along with squalls of heavy rain and high wind. They are often so long, sometimes hundreds of miles long, but only 10 or 20 miles wide. They often pass quickly, and they occasionally produce tornadoes. Squall line thunderstorms can also cause lightning and tornadoes to occur. 

4. Supercell Thunderstorms

Supercell thunderstorms are the largest and the most dangerous type of thunderstorms. They are strong thunderstorms with a rotating updraft (an upward current of air). These thunderstorms usually produce tornadoes, and they can also produce large hail, damaging winds, and flash flooding. 


What Causes Thunder and Lightning?

A cloud contains water droplets and ice particles. Those droplets and particles carry electrical charges, some are positive charges and others are negative. When too many negative charges collect in a cloud, positive charges form under the cloud on the ground in order to balance the negative ones. 

Scientifically, opposite charges attract. So, those negative charges in the cloud attract to the positive ones on the ground. However, electricity does not move easily through air, so it is difficult for the charges to band together. 

The charges get stronger as the cloud grows. Eventually, the charges get stronger than the air, and the cloud releases a strong electrical current with a negative charge. As this negatively charged current heads towards the ground, a positively charged current jumps from the ground to meet it. When the two currents unite, they produce a bright flash that heads back up towards the cloud. This is the lightning flash. 

The loud booming sound that is heard after lightning is the thunder. The electricity from the lightning makes the air very hot. When the air is suddenly heated, it expands very quickly and violently making a loud noise, which is thunder. 

Types of Lightning

There are three primary types of lightning according to the starting and ending points of the flash. Lightning can be “intracloud”, “cloud to cloud”, or “cloud to ground”. It also has two types according to how it appears. Lightning is either a “sheet lightning” or a “fork lightning”. 

1. Intracloud (IC)

The most common type of lightning. Intracloud lightning occurs completely inside a single cloud. The opposite charges in the cloud unite and cause lightning. Intracloud lightning is sheet lightning, because it lights up the sky with a sheet of light instead of a thunderbolt. 

2. Cloud to Cloud (CC) or Intercloud

It is also called “intercloud lightning”. This type of lightning starts and ends between positive and negative charges within two or more different clouds. Here, the lightning strike travels in the air between the clouds. Cloud to cloud lightning produces a thunderbolt, so it is considered fork lightning.

3. Cloud to Ground (CG)

It is the lightning that starts in a cloud and ends on the ground or vice versa. It occurs when currents from a cloud unite with currents from the ground. Cloud to ground lightning produces a thunderbolt, so it is considered a fork lightning. 

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Why Do We See Lightning Before Hearing Thunder?

The reason we see the lightning flash before we can hear thunder is because light travels faster than sound. Lightning is so bright that it can be seen from far distances, but thunder cannot always be heard from far away. In fact, you may sometimes see lightning and do not even hear thunder; in this case, the lightning is pretty far away from where you are. If lightning is very near, thunder will be heard soon after the lightning flash, and its sound will be very loud. If the lightning is farther away, the thunder will be heard a few seconds after the lightning. 

How Far Away is the Lightning?

The lightning flash can be seen from as far as 100 miles, depending on its height and the clarity of the air. On the other hand, thunder is usually heard from less than 15 miles or even less than 5 miles in a noisy city. 

You can estimate how far away the lightning strike is from you by counting the number of seconds that pass between lightning and its thunder sound. Divide the number of seconds by five, the result is approximately how many miles the lightning is far from where you are. For example, if 10 seconds passes between the lightning and the thunder, then the lightning strike is around 2 miles away. 

Lightning can strike as far away as 10 miles from the centre of a thunderstorm. So, if the time delay between lightning and thunder is short, and the distance to the lightning is 6 miles or less, then consider finding shelter.

Effects of Lightning

Thunder may sound really scary, but it does not commonly hurt living creatures. On the contrary, lightning can kill people or cause damage when it strikes.  

  • People struck by lightning can get burns, especially in the head, shoulders and neck. They can also get injured from falling or getting thrown through the air. Although 90 percent of people struck by lightning survive, they suffer from long-term exhausting symptoms because of the damage caused to internal organs and the nervous system. The symptoms include memory loss, sleep disorders, dizziness, numbness, attention deficits, muscle spasms and depression.
  • Lightning seeks an easy path to the ground, so it damages any obstacle in its way. It usually damages buildings or tall structures. It can also damage ships and aeroplanes when it strikes. In addition, the electrical currents brought by the lightning can travel through open water, making it dangerous.

Lightning can also be beneficial. The heat from lightning joins the nitrogen and oxygen in the air, and they together form nitrates and other compounds. When it rains, these nutrients fall to the Earth and nourish the soil, which helps plants grow. 

Warning Signs of a Thunderstorm

It is important that you know the signs of a thunderstorm so that you can seek shelter and keep safe when there is one. Here are some warning signs of a thunderstorm:

  • Lots of dark clouds appear, sometimes suddenly. This is because these clouds are formed by the condensation that happens when warm and cold air clash. These clouds are also fast moving because of the powerful winds.
  • The sky gets dark. The heavy clouds partially block out the sunlight.
  • There will often be a sudden drop in temperature. This is because the cold air sinks down quickly as the warm air rises up in the sky.
  • Winds can suddenly blow or change direction.
  • The most important sign is thunder and lightning. As we learned, lightning can occur up to 15 miles away from the centre of a thunderstorm. So, we can see the lightning and hear the thunder before the storm arrives.
  • There might be interference with electrical devices such as radio and television. This is because of the electrical charges associated with the lightning.

How to Stay Safe During a Thunderstorm

If you are outside during a thunderstorm, these tips will help you keep as safe as possible:

  • When thunder roars, go indoors! Move into your house or any other building.
  • If you cannot get into a building, try to find a shelter outside. A low place under some small trees might be good, but do not shelter under a tree by itself.
  • Do not stand on elevated areas, such as hills or mountain peaks, and try not to be the tallest object.
  • Do not seek shelter in a cliff or rocky overhang.
  • Stay away from ponds, lakes or any other water body because water conducts electricity.
  • Stay away from anything that conducts electricity, such as barbed wire fences, power lines, or windmills.
  • Do not lie flat on the ground. Crouch down like a ball, tuck your head and put your hands over your ears.

If you are indoors during a thunderstorm, follow these tips for safety:

  • Do not use the telephone or any electrical device. Lightning can travel through electrical systems.
  • Do not take a bath, shower, or wash dishes. Avoid any contact with water because lightning can travel through plumbing.
  • Stay away from windows and doors and stay off balconies.

5 of the Worst Lightning Strikes in History

1. Brescia Explosion, 1769

It was one of the deadliest lightning strikes that has ever happened. In the town of Brescia, Italy, a church called the Church of St. Nazaire was used to store gunpowder. Lightning struck the church directly one day in 1769, and all the gunpowder (around 90,000 kg) caught on fire and exploded. The explosion killed around 3,000 people and destroyed a sixth of the city.

2. Dronka Lightning Incident, 1994

On 2 November 1994, a deadly incident happened in Dronka, Asyut Governorate, Egypt. A lightning strike caused fuel tanks belonging to the Egyptian Army strategic reserve to explode. Around 15,000 tonnes of oil leaked from the tanks and mixed with floodwaters. The floodwaters and the oil wiped the village, destroying more than 200 houses and killing 469 people.

3. LANSA Flight 508, 1971

In 1971, Flight 508 from Lima to Pucallpa in Peru crashed into the Amazon rainforest after a lightning strike ignited a fuel tank. All 91 people aboard were killed. The only person who survived was a 17-year-old girl called Juliane Koepcke. She fell 2 miles (3.2 km) down into the Amazon rainforest strapped to her seat. She then walked through the jungle for 10 days until she was rescued by local timber men.

4. Pan Am Flight, 1963

In 1963, A Pan Am flight was struck by lightning when it was about to land in Philadelphia. A part of the wing tore off, and the fuel tank ignited. This accident resulted in the death of all 81 passengers and crew on board.

5. Cows of New South Wales, 2005

In October 2005, a single lightning bolt killed 68 cows on a farm in New South Wales, Australia. The cows were grouped together to be milked when they were struck by lightning.

Quick Facts

  1. Lightning is about four times hotter than the surface of the Sun. The surface of the Sun is about 10,000 degrees Fahrenheit, while a lightning strike can reach 50,000 degrees Fahrenheit.
  2. Air is a poor conductor of electricity, and that’s why it gets very hot when lightning passes through it.
  3. The energy from one lightning flash is so great that it could light a 100 watt light bulb for more than 3 months.
  4. At any given moment, there are an average of 2,000 active thunderstorms across the world.
  5. There are around 16 million thunderstorms across the Earth every year.
  6. About 50 to 100 lightning bolts strike the Earth every second.
  7. Around 2000 people are struck by lightning each year.
  8. Lightning causes an average of 80 deaths and 300 injuries each year.
  9. Thunderstorms do not usually occur in winter because there is not as much moisture and warm air as there is in spring and summer.
  10. When a thunderstorm occurs in winter, it is often called a thundersnow, and it produces snow instead of rain in the precipitation process.
  11. Weak thunderstorms are sometimes called thundershowers.
  12. Thunderstorms do not occur only on Earth, but also on other planets in the Solar System. There have been thunderstorms on Jupiter, Neptune, Saturn and Venus.
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