Why does lightning flash?

When your child asks, here's how to answer — in their words, and in yours.

For your child

Lightning flashes because huge clouds rub together and build up a lot of electrical energy. When there's too much energy, it jumps from one cloud to another, or from a cloud to the ground, making a super bright, quick spark that we see as a flash!

Heads up

The answer simplifies the complex process of charge separation and electrical potential difference within clouds, which is a bit too abstract for this age. Children can grasp that 'lots of energy' builds up and then 'jumps.'

For you

Lightning is caused by a massive discharge of static electricity that builds up in storm clouds. Water and ice particles within the cloud collide, creating an electrical charge separation. When the difference in charge becomes too great, it overcomes the air's insulating properties, leading to a rapid and powerful electrical discharge that we see as a flash.

They might ask next

Does lightning ever flash from the ground up to the sky?
Why does thunder always come after the lightning flash?
Are there other things that make big sparks like lightning?

Whyzard answers your child's own questions — out loud, in words they'll understand.