"Ball lightning" refers to a rare phenomenon that appears as a glowing ball of light in the sky during a thunderstorm. It is not fully understood and can appear in different sizes and colors. Full definition
Most ball lightning lasts from a few seconds to a minute before fading away or exploding. (sciencemag.org)
Many scientists believe ball lightning is a ball of plasma formed when lightning strikes the ground, but the exact mechanism is unclear despite the many theories proposed. (newscientist.com)
The model, he says, explains «90 % to 95 % of the sightings of ball lightning» that scientists have gathered from reliable witnesses. (sciencemag.org)