Here are some of the rarest, weirdest, and scariest forms of lightning out there. Ball lightning looks just like it sounds, and almost no form of lightning is as mysterious. For centuries, people have reported sightings of slowly rotating balls of light — often about the size of a grapefruit — floating above the ground during electrical storms.

Although rare, lightning can also travel from one cloud to another (or more!). Spider lightning refers to long, horizontal moving flashes often seen on the underside of stratiform clouds. (Not to be confused with intracloud lightning within a single cloud).

But cloud-to-ground isn't the only type of lightning—it's not even the most common. From ball lightning to volcanic lightning, here's a tour of some of Mother Nature's most startling displays. Think you can do better?

Lightning may flash on Earth about 100 times per second, but much remains a mystery about it. Scientists have discovered many strange forms of lightning over the years — everything from fiery...

According to the U.S. National Severe Storm Laboratory, there are five to 10 times as many lightning flashes inside clouds as there are cloud-to-ground strikes. Here's a look at the different...