Thunder & Lightning
Know that thunder and lightning happen during thunderstorms: lightning is a giant spark of electricity that forms in clouds, thunder is the sound the lightning makes, and we see lightning before hearing thunder because light travels faster than sound
What a learner can do afterwards
- Describe lightning as a large electrical discharge in clouds
- Explain that thunder is the sound caused by lightning
- State that we see lightning before hearing thunder because light travels faster than sound
1 · Read
Lightning is a giant spark of electricity that builds up inside a storm cloud that grows from the puffy clouds you know. When it jumps out, it lights up the sky in a bright flash. Thunder is the loud sound that comes right after. It is the sound the lightning makes as it rips through the air. Thunder fades with distance, so a far storm may flash with no boom.
Anna is safely inside when a storm rolls in. She sees a bright flash of lightning through the window and starts counting: one, two, three, four. Then she hears a deep boom of thunder. The lightning and thunder happened at the same moment inside the cloud. Anna saw the flash before she heard the boom, because light travels much faster than sound. Light feels instant; sound takes the extra seconds.
Next time you are safely inside during a storm, try counting the seconds between the flash and the boom. The count does not change what happened. It only shows how long the sound took to reach you, since light gets to your eyes almost instantly and sound takes much longer.
Lightning is electricity, thunder is its sound, and you always see the flash before you hear the boom.
The rewritten readings were written for this dataset.
More to read
What the wait before thunder tells you
Light reaches us much sooner than sound does. That is why a lightning flash usually comes before its thunder.
With a grown-up, stay safely indoors and away from windows. At a flash, start counting seconds. Stop at the rumble. The wait helps you estimate how far away that lightning happened because sound needs time to reach you.
A longer wait suggests a greater distance. A very short wait means the lightning is nearby, though not necessarily overhead. Stay inside even if the wait seems long.
Why the flash arrives before the boom
A distant firework shows the difference between the speeds of light and sound. You see its bright flash before you hear the bang.
The same thing happens with lightning, a huge electrical spark that can occur in clouds or between a cloud and the ground. Thunder is the sound it makes. Light reaches your eyes faster than sound travels through the air to your ears, so you see the flash first.
Finding shelter from lightning
Lightning can hurt people. High places and tall objects can be dangerous during storms. Avoid open fields, hilltops and shelter beneath a single tree.
Go to a fully enclosed, sturdy building when thunder sounds. A closed vehicle with a hard roof and shut windows also provides shelter. An open shelter or a roofless car does not.
Hearing thunder means a lightning strike could be near enough to harm you. Stay sheltered for at least 30 minutes after the last thunder. Later, you may notice the storm's fresh smell.
Feeling calmer during a storm
A loud rumble can make a storm frightening. Many people feel nervous, and that feeling is okay.
Thunder is the sound made by lightning, a huge electrical spark. Its boom can seem like a giant drum. Heard from a safe place indoors, thunder is usually harmless.
Make a plan with your family. Pick a comfortable place indoors and gather a torch, a favourite book and a soft toy. Spend the storm together. Learning what makes the flash and the noise can help you feel less afraid.
Explore more
2 · Watch
En anglaisTake it off screen
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.