"Although there is at least one textbook on lightning that questions the existence of ball lightning and I have never seen the phenomenon personally, I feel that there is no question that ball lightning exists. I have talked to six eyewitnesses of the phenomena and think there is no reasonable doubt as to the authenticity of their observations. Furthermore, the reports are all remarkably similar and have common features with the hundreds of observations that appear in the literature.
"Ball lightning is typically described as a luminous ball one to 25 centimeters in diameter having about the intensity of a 20-watt incandescent lamp; the phenomenon usually occurs after a lightning strike. It almost always moves, has a top speed of about three meters per second and floats about one meter above the ground. The motion can be counter to the prevailing breeze and can change direction erratically. Ball lightning may last up to 10 seconds, whereupon the ball extinguishes either noiselessly or with a bang. There have been many observations of ball lightning inside of houses and even in airplanes. There have also been a number of observations of ball lightning passing through closed glass windows, with no apparent damage to the glass. Usually there is no discernible heat production, although a recent observation reported a wooden plank that was singed. Several people have reported the smell of ozone and nitrogen oxides associated with ball lightning and also static in a transistor radio.
"Scientists have struggled for decades to formulate a plausible explanation for the existence of a stable plasma ball. A hot globe of plasma should rise like a hot-air balloon, yet observations do not generally report such behavior. Why does such a ball move, usually counter to the wind? What energy source sustains the lightning ball, given that such a ball would be expected to diminish rapidly in intensity?
"There have been hundreds of papers, and at least three books, discussing ball lightning. Most theories raise more questions than they claim to solve. Probably the most famous theory was advanced by the Russian Nobel Prize winner Pyotr Kapitsa, who claimed that ball lightning is caused by a standing wave of electromagnetic radiation. But why should there be a standing wave of electromagnetic radiation? Other theories assert a variety of sources of energy for ball lightning, including atomic energy, antimatter, burning material or the electrical field from a cloud.
"There is no generally accepted theory of ball lightning. I have my own theory, published in the Journal of Physics D: Applied Physics, ("A Theory of Ball Lightning as an Electric Discharge" in Vol. 29, No. 5, pages 1237-1244; May1996). I propose that ball lightning is powered by the electrical field associated with dispersing charges in the earth after a lightning strike. The movement of the ball is controlled by the velocity of the electrical charge as it disperses in the ground after the initial period of electrical 'breakdown' that occurs at the moment of the strike. In my paper, I suggest that this discharge is similar to a corona discharge (as occurs around high-voltage transformers) and consists of a succession of electrical pulses that take place on a microsecond time scale.