1 NEWS’ weather expert Dan Corbett has given a graphic explanation of what causes lightning after this morning's ferocious thunder storm that battered Auckland and other parts of the North Island.
The storm has left a woman recovering from being struck by lightning in South Auckland and four farm animals dead. And some residents remain without power after lightning hit houses, disrupted flights and closed schools.
Corbett said the sky got noticeably darker as thunderstorms closed in this morning - a sure sigh of potential strikes.
Lightning begins as static charges in the rain clouds, he explained.
"Turbulent winds push moisture and frozen water droplets around. They bump into each other and these collisions create the electric charge.
They fill up the cloud - positive charges at the top, heavier, negative ones at the bottom."
And of course, opposites attract.
"And very simply put, the negative charges fall to earth, the positive electricity rises from the ground. And when they connect, zap - lightning strikes."
As for the booming sound, that's caused by the increase of pressure and temperature in the air surrounding, and within a thunder bolt, our weatherman explained.