Let's think about Lightning - Smarter Every Day 15

Destin explains the scenario of standing on the ground while lightning strikes far away in the sky during a thunderstorm.

• Lightning breaks the sound barrier and creates a sound wave that travels toward you • The electricity in the lightning bolt travels much faster than sound • Lightning outrun the sound waves it creates

Sound is simultaneously initiated from all points along the lightning bolt at the same time, creating cracks that happen before other cracks, resulting in a low rumble.

• When lightning is very far away, all the sound might reach you at the same time • When closer, you get a long drawn out thunder rumble because sound arrives from different points along the bolt at different times • The final result depends on the distance of the lightning bolt, your position, and the speed of sound