Ball lightning

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Image:Ball Lightning.jpg TEST 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). [1]

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 (A. B. Pippard, (1982), Ball of Fire?, Nature v298, p702)

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Reports

Ball lightning discharges were once thought to be extremely rare occurrences, but recent research shows that a few percent of the US population have been witnesses (Uman). Ball lightning is photographed very rarely, and details of witness accounts can vary widely. Many of the properties observed in ball lightning accounts conflict with each other, and it is very possible that several different phenomena are being incorrectly grouped together. The discharges can appear during thunderstorms, sometimes issuing from a lightning flash, but large numbers of encounters occur during good weather with no storms within hundreds of miles. Ball Lightning tends to float (or hover) in the air and take on a ball-like appearance. The shape can be spherical, ovoid, teardrop, or rod-like with one dimension being much larger than the others. The longest dimension observed is between fifteen and forty centimeters. Many are red to yellow in color, sometimes transparent, and some contain radial filaments or sparks.

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.

Image:Ball lightning.PNG

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, ball lightning appeared, 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.

Many attempts have been made over the years to produce ball lightning in the laboratory, but it is easy to mistake other phenomena for ball lightning. Most prominent among these are glowing spheres produced by high-energy arcs between metal electrodes. Such arcs often expel small droplets of molten metal that are heated to extremely high temperatures. Because of their high heat content, these droplets will continue to glow quite brightly for several seconds after landing on a floor or other surface, and their odd physical characteristics can cause them to roll, still glowing brightly, for some distance after landing. They thus mimic the most common description of ball lightning before cooling down into a small speck of metallic dust. The most familiar instance of these glowing spheres is the "weld spatter" usually seen during arc welding operations. The spheres can also be produced when a switch carrying very large electric currents is operated improperly, or during certain grinding or other machining operations.

Recently scientists at Tel Aviv University have claimed to have produced ball lightning in the lab using a microwave drill and ceramic substrate. (see [2])

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Analysis

For a long time the phenomenon was treated as myth. Although speculation continues, there is now agreement that it is neither mythical nor purely psychological. Surveys have been taken of eyewitness accounts by at least 3000 people, and it has been photographed several times. There is as yet no widely accepted explanation.

Difficult features of the lightning include its persistence and its near-neutral buoyancy in air. There has been no convincing laboratory demonstration of ball lightning until February 2006 when Israeli scientists announced that they had created a short-lived effect using the same technology found in microwave ovens.

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.
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Esoteric explanations

The natural phenomenon of ball lighting has been reportedly the source of some reports of supernatural phenomena, ranging from will o' the wisps to UFOs. Some people believe the ball lightning phenomena are ghosts or spirits. References can be seen in the will o' the wisp and other spirits that take the guise of orbs of light. Some UFO skeptics have suggested that many apparent close encounters are actually observations of ball lightning. UFO enthusiasts report seeing ball lightning often at crop circle sites and believe them to be some kind of intelligence or come from some kind of intelligence while not denying that it is indeed ball lightning.

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Quotations

"...Our conclusion is that these fireballs are primarily RF in origin, and not nuclear phenomena..." - Corum
"...No theory of ball lightning exists which can account for both the degree of mobility that the ball exhibits and for the fact that it does not rise...." - Talbot
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See also

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Further reading

  • Barry, James Dale. Ball Lightning and Bead Lightning. New York: Plenum Press. 1980.
  • Cade, Cecil Maxwell and Delphine Davis. The Taming of the Thunderbolts. New York: Abelard-Schuman Limited. 1969.
  • Coleman, Peter F. Great Balls of Fire-A Unified Theory of Ball Lightning,UFOs, Tunguska and other Anomalous Lights. Christchurh,NZ : Fireshine Press. 2004.
  • Golde, R. H. Lightning. Bristol: John Wright and Sons Limited. 1977.
  • Golde, R. H. Lightning Volume 1 Physics of Lightning. Academic Press. 1977.
  • Singer, Stanley. The Nature of Ball Lightning. New York: Plenum Press. 1971.
  • Singer, Stanley. Ball lightning: the scientific effort, Phil. Trans. R. Soc. London v360, pp5-9. 2002.
  • Stenhoff, Mark. Ball Lightning, An Unsolved Problem in Atmospheric Physics. New York, Boston,Dordrecht, London, Moscow: Kluwer Academic/Plenum Publishers. 1999.
  • Uman, Martin A. Lightning. Dover Publications 1984.
  • Viemeister, Peter E. The Lightning Book. Cambridge: MIT Press. 1972.
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External links

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