Lightning does not go straight down. It has to find its way down bit by bit.
How does it start?
A storm cloud fills up with electricity. Then a thin spark starts moving down in small jumps.
Why the zigzag?
The spark cannot see the ground, only the air right next to it. So every jump goes a different way and the path zigzags.
Where does the flash come from?
Near the ground, a spark shoots up from a tree to meet it. When they touch, the whole path lights up in a huge flash.
Which way does it go?
And here is the surprise. The flash starts at the bottom. It zooms up the zigzag path back into the cloud.
Sources
- NWS: Initiation and the stepped leader
- NWS: Connection to the ground
- NWS: The return stroke
- NWS: Slow motion flashes
- NWS Melbourne: What is lightning?
- NSSL: Lightning types
- Britannica: Cloud-to-ground lightning
- Live Science: Why does lightning zigzag?
- BBC Science Focus: Why doesn't lightning strike straight to Earth?
