Ball lightning is an atmospheric phenomenon, the physical nature of which is still controversial. The term refers to reports of luminous, usually spherical objects which vary from pea-sized to several meters in diameter.
It is sometimes associated with thunderstorms, but unlike lightning flashes, which last only a fraction of a second, ball lightning reportedly lasts many seconds. Laboratory experiments have produced effects that are visually similar to reports of ball lightning, but it is presently unknown whether these are actually related to any naturally occurring phenomenon. Scientific data on natural ball lightning is scarce due to its infrequency and unpredictability. The presumption of its existence is based on reported public sightings, and has therefore produced somewhat inconsistent findings. Due to inconsistencies and the lack of reliable data, the true nature of ball lightning is still unknown.
Until recently, ball lightning was often regarded as a fantasy or a hoax.Reports of the phenomenon were dismissed due to lack of physical evidence, and were often regarded the same way as UFO sightings. Recently however, the overwhelming number of sightings has caused a renewed interest in studying its existence.
Depending on the report, ball lightning can move upwards as well as downwards, sideways, or in odd trajectories such as rocking from side to side like a falling leaf. It can move with or against the wind, or simply hover, more or less stationary in the air. Sometimes it is described as being attracted to houses, cars, persons, or other objects, but sometimes the balls are reportedly repelled or are unaffected by objects. Some accounts claim the balls have passed freely through solid masses, such as wood or metal, without any effect on the ball or material, while other accounts report damage to the material, such as melting or burning. Some reports suggest an attraction to, or even an origination from electric power lines.
Ball lightning has been reported in many different colors, sometimes even transparent or translucent. It is sometimes said to contain radial filaments or sparks while others are evenly lit, and some have flames protruding from the ball surface. Its shape has been described as spherical, oval, tear-drop, or rod-like.
It has sometimes been reported during thunderstorms, sometimes issuing from a lightning flash, while sometimes it appears during calm weather with no storms in the vicinity.
The balls have been reported to disperse in many different ways, such as suddenly vanishing, gradually dissipating, absorption into an object, "pop"ing, exploding loudly, or even exploding with force, which is sometimes reported as damaging. Some accounts say the balls are lethal, killing on contact, while other accounts claim that they are harmless. Perhaps the most famous story of ball lightning unfolded when 18th-century physicist Georg Wilhelm Richmann installed a lightning rod in his home and was struck in the head - and killed - by a "pale blue ball of fire.
Natural ball lightning appears infrequently and unpredictably, and is therefore rarely (if ever truly) photographed. Although some do exist as proof.
