by David Murphy
Ball Lightning, as the name suggests, is lightning that takes on the shape of a ball, sometimes rolling across the ground or across the floor of a room. It's very rarely seen. I've never seen it. As of this writing, I've never met anyone who has. But those who've reported a sighting say it's memorable.
Typically, ball lightning is about the size of a grapefruit or smaller and only survives for a few seconds, according to most witness accounts. It's often red or yellow and apparently does not produce much heat in most cases (although some report minor burns to material like carpet in its wake). Ball lightning is almost always seen during thunderstorms, usually right after a lightning stroke. It is apparently a lingering mass of energy that takes a few extra seconds to diffuse into the ground. Martin A. Uman writes in his book, All About Lightning (Dover Publications, Inc.) that some scientists attribute the phenomena to an optical effect left over after someone sees a lightning flash at close range; in other words, they theorize that it isn't actually real. But there have been thousands of witness accounts, lending credence to its existence.