When Ben Franklin came in from the storm with his key and kite, he brought back some important facts about electricity for all the world.
We now know that lightning is an electrical current that flows from one cloud to another, or from one cloud down to earth. The tiny droplets of water in clouds have electrical charges on their surface. The larger droplets have positive electrical charges, and the smaller ones negative charges. When these charges come near each other, they produce a huge spark, a lightning flash.
The same thing occurs when opposite charges between clouds and earth come close to each other.
When lightning from cloud to cloud gives off electrical current, that current travels only through the air and doesn’t cause damage. But lightning from clouds to earth can cause property damage and death because it passes through whatever is in its path on the way to the ground, trees, water, and even people.
Lightning flashes between clouds can travel up to distances of 20 miles. Lightening flashes from clouds to earth may travel up to eight miles. But both travel at speeds up to 100,000,000 feet per second.
The electrical current in a one-mile-long lightning flash provides enough power to light 1,000,000 light bulbs!