Lightning · Rainbow CloudtopScience for kids

Why do we see lightning before we hear thunder?

In short: Lightning is a giant electric spark in a storm cloud, and thunder is the boom it makes by heating the air. Both happen at once, but light travels far faster than sound, so the flash reaches you first.

How it works

Inside a thunderstorm, rising air makes ice pellets, soft hail and water droplets crash into each other. A bit like rubbing a balloon on your hair, this separates electric charges: the top of the cloud usually becomes positive and the bottom negative. When enough charge builds up, it jumps as a huge spark, which is lightning.

The air along the lightning's path heats up in a split second, becoming hotter than the surface of the Sun. It expands so fast that it bangs outwards, making thunder. Close by you hear a sharp crack; further away, sound from different parts of the long flash arrives at different times, so it rumbles.

Light reaches you almost instantly, but sound takes about three seconds to travel one kilometre. Count the seconds from flash to thunder and divide by three to estimate the distance in kilometres. If you can hear thunder, lightning is close enough to be dangerous, so head indoors.

Where to see it in New Zealand

New Zealand has fewer thunderstorms than many tropical places, but they do happen, sometimes bringing hail and strong gusts. Forecasters issue warnings when severe thunderstorms are expected. When you hear thunder, leave beaches, pools and open sports fields and shelter inside a solid building.

Try it together

During the next thunderstorm, stay indoors, close the windows and watch from a few steps back. When you see a flash, count 'one thousand and one, one thousand and two' until the thunder rumbles. Divide by three to find roughly how many kilometres away it is. Is the storm coming closer or moving away?

Kids also ask

Can lightning strike the same place twice?

Yes. The old saying is a myth. Tall buildings, towers and mountain tops are struck often, and some skyscrapers are hit many times in a single year.

Is a car safe in a thunderstorm?

A hard-topped metal car with the windows shut is much safer than being outside, because the electricity mostly flows around the metal body into the ground. Convertibles are not safe. A solid building is still the best shelter.

In the game, “Lightning” is a nature card on Rainbow Cloudtop.

Your child finds this card by reaching the right place or meeting the right weather on the island, and lights it up by answering the question on the back. Tap the button below and the game shows your child which island it is on and how to find it. Mochi Isle is a browser learning game for ages 5 to 18; the main island and the daily lesson are free.

Find “Lightning” on the island ↗ All cards from Rainbow Cloudtop