Ball lightning

Ball lightning is a rare and unexplained phenomenon described as luminescent, spherical objects that vary from pea-sized to several meters in diameter. Though usually associated with thunderstorms,^[1] the observed phenomenon is reported to last considerably longer than the split-second flash of a lightning bolt, and is a phenomenon distinct from St. Elmo's fire.

Some 19th-century reports^[2][3] describe balls that eventually explode and leave behind an odor of sulfur. Descriptions of ball lightning appear in a variety of accounts over the centuries and have received attention from scientists.^[4] An optical spectrum of what appears to have been a ball lightning event was published in January 2014 and included a video at high frame rate.^[5][6] Laboratory experiments have produced effects that are visually similar to reports of ball lightning, but how these relate to the supposed phenomenon remains unclear.^[7][8]