What is ball lightning, a reality or myth?

"Ball lightning is an unexplained and potentially dangerous atmospheric electrical phenomenon. The term refers to reports of luminescent, spherical objects that vary from pea-sized to several meters in diameter. Though usually associated with thunderstorms, the phenomenon lasts considerably longer than the split-second flash of a lightning bolt. Two reports from the nineteenth century say that the ball eventually explodes, leaving behind an odor of sulfur. The actual existence of the ball lightn