Why is lightning zigzag?
Lightning is the electricity generated when ice in the clouds collides with each other.
Electricity that is too large to fit in the clouds can overflow to the surface of the earth.
This is a lightning strike.
A lightning strike that departs from a cloud reaches the surface of the earth by following a moist place in the atmosphere.
So the lightning goes in a zigzag rather than a straight line.
– NSSL: Severe Weather 101