Ball lightning is a natural phenomenon, or debatably, a pseudoscientific theory. It is sometimes associated with thunderstorms. It takes the form of a long-lived, glowing, floating object, as opposed to the short-lived arcing between two points commonly associated with lightning. An early attempt to explain ball lightning was recorded by Nikola Tesla on March 5, 1904 (Electrical World and Engineer).
Some laboratory experiments claim to produce ball lightning, but there is no consensus that the phenomenon reproduced is related to the natural one. The natural occurrences are, by their nature, difficult to document accurately. Consequently many scientists continue to dispute the existence of ball lightning as a distinct physical phenomenon (see, for example, the review by Singer (2002)). In one such occurrence, Singer reports that staff at the Cavendish Laboratory, Cambridge apparently saw ball lightning, although Brian Pippard, the Head of Department, was skeptical on its reality.
Sometimes the discharge appears to be attracted to a certain object, and sometimes to move randomly. After several seconds the discharge leaves, disperses, is absorbed into something, or, rarely, vanishes in an explosion.
Ball lightning has been seen in places as diverse as "escorting" World War II bombers, flying alongside their wingtips. During this period, due to the enigmatic nature of this phenomenon, these appearances were referred to as "foo fighters." Other accounts place ball lightning as appearing over a kitchen stove to wandering down the aisle of an airliner. One report described ball lightning engulfing and following a car, causing the electrical supply to overload and fail.
One of the earliest recorded, and most destructive, occurrences is thought to have taken place during The Great Thunderstorm at Widecombe-in-the-Moor, Devon, in the United Kingdom, on October 21, 1638. Four people died and around 60 were injured when what appears to have been ball lightning struck a church.
Another reference to ball lightning appears in Laura Ingalls Wilder's book On the Banks of Plum Creek [Harper Trophy, 1937] in which the lightning appears during a thunderstorm near a cast iron stove in the family's kitchen. It is described as appearing near the stovepipe, then rolling across the floor, only to disappear as the mother chases it with a willow-branch broom.
Notorious British occultist Aleister Crowley also reported witnessing what he referred to as "globular electricity" during a thunderstorm on Lake Pasquaney in New Hampshire in 1916. As related in his Confessions, he was sheltered in a small cottage when he "noticed, with what I can only describe as calm amazement, that a dazzling globe of electric fire, apparently between six and twelve inches in diameter, was stationary about six inches below and to the right of my right knee. As I looked at it, it exploded with a sharp report quite impossible to confuse with the continuous turmoil of the lightning, thunder and hail, or that of the lashed water and smashed wood which was creating a pandemonium outside the cottage. I felt a very slight shock in the middle of my right hand, which was closer to the globe than any other part of my body."
A famous example of the violent potential of ball lightning occurred in 1753 when Professor Georg Richmann, of Saint Petersburg, Russia created a kite flying aparatus similar to that built by Benjamin Franklin a year earlier. He was attending a meeting of the Academy of Sciences, when he heard thunder. The Professor ran home with his engraver to capture the event for posterity. While the experiment was underway, a large ball lightning showed up, collided with Richmann's head and killed him, leaving a red spot. His shoes were blown open, parts of his clothes singed, the engraver knocked out; the doorframe of the room was split, and the door itself torn off its hinges.
Recently scientists at Tel Aviv University claim to have produced ball lightning in the lab using a microwave drill and ceramic substrate.
A popular hypothesis is that ball lightning is a highly ionized plasma contained by self-generated magnetic fields: a plasmoid. This hypothesis is not initially credible. If the gas is highly ionized, and if it is near thermodynamic equilibrium, then it must be very hot. Since it must be in pressure equilibrium with the surrounding air, it will be much lighter and hence float up rapidly. Magnetic fields, if present, might provide the plasmoid's coherence, but will not reduce this buoyancy. In addition a hot plasma cannot persist for long, because of recombination and heat conduction.
There may, however, be some novel form of plasma for which the above arguments do not fully apply. For example, a plasma may be composed of negative and positive ions, rather than electrons and positive ions. In that case, the recombination may be rather slow even at ambient temperature. One such theory involves positively charged hydrogen and negatively charged nitrites (NO2) and nitrates (NO3). In this theory, the role of the ions as seeds for the condensation of water droplets plays an important role.
Other suggestions include:
- that some stored chemical energy is slowly being released, providing persistence and thrust.
- that ball lightning is some form of induction phenomenon. (Ball lightning having allegedly been witnessed inside metal aircraft.)
- that the lightning is a Hill's vortex, like a smoke ring.
