Ball lightning – a natural phenomenon or sensory deception?

by Dr. Alexander G. Keul, Salzburg

 
The formation of ball lightning remains a riddle of atmospheric physics (Stenhoff, 1999). Is it a still unexplained natural phenomenon, a side-effect of a conventional cloud-ground lightning flashes or only sensory deception?

"It must have been mid-August [1968], when in the afternoon, at about 3 P.M., a heavy thunderstorm hit the area of Maria Woerth [Carinthia, Austria]. [We] were in the Villa Anna immediately near the lakeshore [of Lake Woerther]. After a violent lightning flash and thunderclap (simultaneously), a brightly shining ball of approximately 20 cm diameter with a discharge corona moved through the room, hissing like a Christmas sparkler, to the open balcony door, then along a wooden balcony pillar to the ground and about a further 300 m out onto the lake surface, where another discharge happened with the sound of thunder. The movement of the ball was steadily linear and rotating. It is still puzzling for me today how the ball entered the building since the windows were closed and they later had no traces. The ball moved above the floor in bed height. At the wooden balcony pillar it caused fire damage, i.e. at several spots the timber was smoldering, and afterwards we also found some shattered roof tiles in front of the house. After the event, there was a sulphur-like smell in the room. Obviously through discharges at the ball’s surface, NOx-compounds originated. My wife and I were not hurt by this incident, but nevertheless suffered a proper shock. We were about 1.5 m distant from the ball lightning track. According to my memory, the ball had a relatively clear outline. I would call its color white-blue with a slightly reddish touch."
(Alfred Geiswinkler, 1997, personal communication). 

This elaborate technical report of a certified electrical engineer, retired BEWAG director (the electricity company of Burgenland Federal Province), stands for thousands of eyewitness reports worldwide that still leave scientists amazed.

The first (and only) German-language scientific book on ball lightning by Walther Brand (1923) appeared 90 years ago and listed over 100 case reports. A reprint of the book appeared in 2010. The recent research situation was summed up by Professor Martin A. Uman, senior lightning expert of the University of Florida (1987, 23):

"Despite the relative wealth of similar ball lightning observations over a period of centuries, reports that leave little doubts as to its reality, there is still no consensus as to the physical mechanism or mechanisms responsible for ball lightning".

The astrophysicist Axel Wittmann, Goettingen Observatory, Germany, compiled the following, still valid, fact file about the phenomenon (1976):


In a 2000-2001 research project, the author statistically evaluated over 400 case reports from Central Europe, among them 250 from Austria (Keul & Stummer, 2002). The most ball lightning rich Austrian areas were Styria, Lower and Upper Austria. Reports had not gender effect; the age of the observers was between 16 and 93. The cases scattered throughout the 20th century. 85 percent of the cases occurred in the summer, 70 percent during thunderstorms. Only one object was seen in over 90 percent of the cases, in every second case less than five meters (!) distance, vanishing usually within three to five seconds. The object size was 25 to 30 centimeters. 60 percent of the objects shone red-orange-yellow, over 10 percent emitted sparks. Every third case happened inside buildings, often scaring observers. With a case density of 1 per 28,000 inhabitants, Austria even lies before Japan (1:61,000) internationally. 

Eyewitness reports can show large subjective variations. What about actual "hard" physical proof? A U.S. research project examined the photo material of the "Prairie Network", camera stations that photographed meteorite falls at night, and found 120,000 lightning events, but only 24 ball and bead lightning records (the latter shows several objects; Barry, 1980). In 1978, Werner Burger from St.Gallenkirch in the Montafon Valley (Vorarlberg,  Austria) was lucky to obtain an especially detail-rich nighttime ball lightning color photograph by time exposure (Keul, 1992). Despite numerous expert appraisals and two computer image analyses the case is still unexplained.

 
1992, a ball lightning case at Perg, Upper Austria, was analyzed by psychology (witness interview), lightning protection (securing of traces) and a lightning location network expert (ALDIS). It showed traces of a low-energy CG lightning flash (Keul, Gugenbauer & Diendorfer, 1993).

On April 19, 2003, Sabine and Thomas Fuchs, two teenagers from Zwoenitz, Saxony, Germany, were filming lightning flashes with their webcam with laptop connection at 6:45 P.M. On the four minutes record, they later discovered a strange object which flew upwards over the opposite rooftop within two seconds in a "wavy" trajectory. It is white-yellow on the video, shows "smoke" and two luminous outbreaks. 56 webcam single frames were superposed, measured and screened for possible fraud by video experts of the Department for Digital Television at Salzburg College - they did not find any sign for it (Keul, 2004).


The lightning handbook of Rakov and Uman (2003) lists 16 explanation models in a chapter about ball lightning: 11 theories with an inner source of energy (combustion, plasma, vortex, charge separation, nuclear energy) and 5 with an outer source of energy (EM field, earth EM feld, cosmic radiation, antimatter). To be ecologically valid, a theoretical explanation must match the data of natural observations and experiments, which is still left to do.

Beside the 16 explanatory categories of Rakov and Uman, there were attempts (e.g. from the Swiss lightning research pioneer Berger) to explain ball lightning as sensory deception. Berger and others suggested a dazzling of the human eye by a near lightning flash and its after-image (however, its color would have to change, it would have to move together with head/eye motion and always cover objects of the environment). With the emergence of electromagnetic records (MRI) and stimulation (TMS) of the human brain, a new hypothesis claimed that ball lightning could be a EM hallucination caused by nearby lightning flashes. Without unambiguous experimental results, positive (e.g. Cooray  & Cooray, 2008) and negative effect estimations (e.g. Keul, Sauseng  & Diendorfer, 2008) contradict each other.
 
An interesting field experiment was arranged by the Martin Uman research group at Florida (Hill, Uman et al., 2010): On their rocket-firing range at Camp Blanding, where artificial lightning discharges have been triggered repeatedly, in 2008 eight triggered discharges were led over several prepared materials. Over saltwater, silicon wafers, a steel surface or coniferous branches, luminous phenomena were recorded for one half to one second caused by ionization and combustion. The researchers don't claim to have generated ball lightning, however, the optical effects were produced by quite different causes (arcs on steel, silicon, saltwater, wood). A light ball on steel reached 33 centimeters on the film record.

Ball lightning research therefore remains exciting, even without big research budgets. In 1988, a first international congress was held in Japan and an Internationally Committee on Ball Lightning was established that organizes congresses every two years.
English short reports on some ICBL congresses can be found at:
http://home.planet.nl/~icblsec/pg_reports.html
Vladimir Bychkov, vice-president of the ICBL, finds that further progress will be possible by a closer  look at the interaction of ball lightning with solid materials (metal, sand, glass) and he prefers a physical ball lightning model with combustion of solid materials in the plasma (Bychkov et al., 2010). 

Ball lightning as a phenomenon is known all over Europe. In Estonia it is called keravälk, in Denmark kuglelyn, in Hungary gömbvillam, in Iceland urdarmani (Keul, 2005). The technical memorandum COST P18, signed by Europe's 30 leading lightning-researchers, also quotes ball lightning as a research topic (Thottapillil, 2005).

Visitors who have seen ball lightning or know about a case, a photo or a video, are asked to send in a short note to the author. Each letter/email is answered and, if necessary, treated confidentially.
 

Dr. Alexander G. Keul
Salzburg University, Hellbrunnerstr. 34, 5020 Salzburg (Austria)
e-mail: alexander.keul(at)sbg.ac.at
 

Literatur

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