...Following an intense flash of lightning, there appeared a 'ball of fire' hovering about 30cm above the surface of the water, apparently unaffected by the prevailing wind. The ball then crackled and hissed as it flew past his head before passing into a group of nearby trees...
The evidence for Ball lightning
For those of us living in temperate latitudes the most dramatic demonstration of the raw force of nature is often afforded by a spectacular electric storm. And the statistics are equally impressive: at any instant there may be 2000 active thunderstorms around the world creating 100 lightning flashes occurring every second, with one moderately sized storm generating several hundred megawatts of power - equivalent to a small nuclear power station. With each lightning strike discharging currents as high as 20000 amps in a tiny fraction of a second, it comes as little surprise that such storms can be accompanied by rarely seen and as yet poorly understood phenomena.
Much recent research has concentrated on the mysterious red 'sprites' and blue jets seen to dance above active storms (see issue one of AA&ES, pages 47-49), but perhaps the strangest manifestation of all is ball lightning which has been reported the world over since accurate records began. It generally takes the form of a glowing sphere, 1 to 100cm (0.4 to 40") in diameter, lasts for seconds rather than minutes and can follow a meandering path at speeds of a few metres per second before vanishing silently or with a small explosion. While there are still some scientists that doubt its existence, there are many more that are increasingly of the opinion that reliable eye-witness reports - a few of which follow - are describing a similar phenomenon.
An account from Rushford, near the town of Thetford in the county of Norfolk, concerns some farm labourers helping to gather the asparagus harvest in May 1949. Peggy Filby and her teenage sister Delia were among the group that took to the shelter of a tarpaulin covered trailer in the open field once the heavy rain from an approaching thunderstorm began to fall. Soon after, a loud report coinciding with a brilliant flash signalled a nearby lightning strike.
Delia and other members of the group then saw what was described as a football-sized, softly glowing orange-red ball of light. It emitted neither sparks or rays, nor did it vary in luminosity as it appeared to 'bounce' across the field in the direction of the startled witnesses. Within a few seconds the ball disappeared soundlessly once it reached the metal trailer and Delia was one of the workers who experienced something akin to an electric shock as it did so.
The year 1967 found M. Dmitriev, a Russian chemist, camping on the banks of the River Onegaw. He claims that, following an intense flash of lightning, there appeared a 'ball of fire' hovering about 30cm above the surface of the water, apparently unaffected by the prevailing wind. The ball then crackled and hissed as it flew past his head before passing into a group of nearby trees. Dmitriev then describes the sphere apparently bouncing from tree to tree "like a billiard ball" and emitting a trail of bluish smoke. After a few minutes it was lost to view.
Another startling sighting - and certainly one of the most detailed and scientifically credible - comes from Professor Roger Jennison (Department of Electronics, University of Kent) concerning his experiences on board a late-night flight from New York to Washington in March 1963. He later wrote of his experiences in the November 1969 issue of Nature. Jennison states that the phenomenon occurred after the aircraft encountered a thunderstorm in which it was enveloped by a bright and audible electrical discharge.
Some seconds later a glowing sphere some 20cm in diameter emerged from the pilot's cabin and passed down the aircraft's central aisle approximately 50cm from Jennison. The ball moved on a straight course the whole length of the aisle 75cm above the floor at a velocity relative to the aircraft of about 1.5 ms-1. It was blue-white in colour and its optical output amounted to about 5 to 10 Watts. Interestingly, no heat was felt when it passed close by and the limb darkening (like that of the Sun) gave it an almost solid appearance, indicating that it was optically opaque. No asymmetry could be seen in any dimension so it was impossible to determine whether or not it was spinning.
Prof. Jennison's observation is interesting since it is hopefully revealing of the nature of ball lightning. It generally occurs shortly after normal cloud to ground lightning and, from this latter case, is capable of being generated within an electrically screened environment since the aircraft fuselage would act very much like a Faraday cage. It appears to be able to pass through glass and other solid objects, sometimes causing damage to them in the process, yet it doesn't emit heat (though there are exceptions to this that may relate to another class of object, as we shall see in a moment). Sometimes a hissing or crackling sound is emitted, or it may be perfectly silent.
One of the favoured explanations offered by sceptics is that the ball is merely an ignited puff of gas released when lightning strikes the ground. This may explain a fleeting 'Will-O'-the-Wisp' seen in marshy areas where naturally occurring methane gas may be liberated from rotting organic matter, but it fails to account for the previous sighting in the aircraft. Also, how is a burning flame to pass through a solid object or not to radiate heat when it is clearly seen to pass close by? Another suggestion that ball lightning is merely the familiar after-image seen hovering in front of the eyes following a sudden exposure to a bright light is equally untenable.
A simple answer to the phenomenon doesn't appear to be forthcoming and tentative explanations rely heavily on theoretical physics. One of the current favourites concerns electromagnetic plasmoid models: the greatest problem for the theorist is explaining how sufficient energy be contained within such a small space without it being emitted steadily and continuously, but sometimes suddenly. Dr. Geoff Endean (School of Engineering and Computer Science, University of Durham) has suggested that the energy containment problem can be circumvented since a very rapidly rotating electric field can exist in a plasma without a magnetic field with no apparent limit to the electrical field strength - heady stuff indeed.
Furthermore, it has also been suggested that ball lightning may occur quite frequently but the electromagnetism associated with it is not strong enough to render it visible to the eye on the vast majority of occasions. Another rather more radical theory invokes anti-matter as the root cause. The idea is that it is drawn down from the upper atmosphere by the circulating air currents in thunderstorms where it interacts with ordinary terrestrial matter, whereupon both are annihilated with a tremendous release of energy that makes the glowing ball. With the lack of solid scientific evidence or theory, however, it is almost inevitable that there are also those on the fringe who attribute an extra-terrestrial origin to the light phenomenon.
Whatever it may turn out to be and however it manifests itself, there are countless eye-witness reports that describe a phenomenon of apparently similar nature to ball lightning that occurs in fine weather away from any storms or lightning. These are the so-called Earth lights or Earthquake lights, and they offer a fascinating glimpse of a new branch of geological science that could offer an explanation to the vast majority of UFO sightings. This is what we shall explore next month.
by Adrian Ashford