When I was a nuclear physics graduate student some decades ago, I spent some time teaching myself about plasma physics by reading textbooks.  While doing this, I also tried to apply the ideas I was learning to a very mysterious physical phenomenon, ball lightning.  Eventually I became frustrated and put the problem aside.  Except for using ball lightning as a techno-prop in my hard-SF first novel, Twistor, I had more-or-less forgotten about this puzzling phenomenon until recently, when I had the pleasure of a visit from Prof. Peter Handel of the University of Missouri in St. Louis, one of the theorists who has developed a possible explanation of the phenomenon.  I will devote this column to ball lightning.

Few people have actually seen ball lightning, because its production seems to be a very rare event.  Nevertheless, the phenomenon has been widely reported since the Middle Ages.  Over 10,000 reports of observations of ball lightning have been collected in a database in Russia , primarily from reports from Russia, Japan, and Europe.  While this suggests that ball lightning may occur frequently, all attempts by scientists at systematic detection and observation have failed.  Handel suggests (see below) that this failure may be because such scientific "lightning observatories" have been placed in mountainous regions (because there is more lightning there), while ball lightning is observed mainly in flat landscapes.

A typical observation goes something like this.  There is a normal lightning strike, and afterwards a glowing ball is observed.  The ball may range from tennis ball to beach ball size.  It may hover in the air, or move horizontally, often erratically, or bounce or roll on the ground, or climb a tree or utility pole, or race along a power line.  Its color is usually a brilliant white, but bright red, blue, and green glows have also been reported.  Some observers have reported seeing tangled filamentary structures within the ball.  It sometimes makes a buzzing, hissing, or frying noise and may have an acrid odor like ozone or sulfur dioxide, or nitric oxide.  It usually lasts a few seconds, and its disappearance may be silent, or may be punctuated by a loud bang or explosion, perhaps with glowing streamers.  The ball lightning may float into a building or car or airplane, but curiously seems to do little damage when this happens, despite its sometimes explosive and high-energy behavior in open areas.  There have been many reports of a lightning ball passing through a glass window pane, occasionally damaging the glass but usually not.  There have also been reports of ball lightning quenching in a tub of water and bringing the water to a boil.  There was one incident where a lightning ball quenched in a rain barrel, and the water temperature was measured shortly afterwards.  The amount of energy contained in a lightning ball is variable and not well quantified, but it is estimated to range from about 10² to 10⁸ joules.

Among the many reports, perhaps 15 were made by scientists, including some quite distinguished in fields like astronomy, physics, and atmospheric science.  The staff of the Cavendish Laboratory at Cambridge University in the UK reported one such observation.  There have been a few photographs by observers who saw the phenomenon and snapped a picture.  There have been many more photographs from cameras left on time exposure to record lightning in a storm, with a ball lightning image discovered later when the film was developed.  The have also been a few reports of man-made ball lightning.  Some of these were accidents, like the unintentional shorting of a large submarine battery, but others were planned.  Plasma physicists have produced "plasmoids", spheres of magnetically self-confined plasma that bear some resemblance of ball lightning, but these are created only in good vacuum conditions and had millisecond lifetimes or less.  There were also Soviet experiments in 1977 in which researchers used electrical discharges with potentials of up to 12 kV to vaporize tubes of ice or plastic in atmosphere, producing brilliant balls about the same size as those reported for ball lightning, but these lasted only a few milliseconds.  Systematic efforts to create long-lived balls from discharges have not been successful.

For the past few centuries reports of ball lightning have attracted the attention of many scientists, including Arago, Faraday, Arrhenius, Kelvin, Boys, and Kapista.  Faraday doubted the existence of ball lightning, but many others have speculated on its underlying mechanism.  However, the ball lightning characteristics of high energy content, floating or moving in mid-air at atmospheric pressure (instead of rising or falling), and the relatively long lifetime has eluded plausible theoretical explanation.  Nevertheless, the literature of published papers and conference proceedings contains on the order of 100 theories attempting to explain ball lightning.  However, not one of these theories has gained acceptance outside its own circle of advocates.  This is the kind of scientific situation that arises when rival theories describe a rare and mysterious phenomenon, so that the predictions of the theories cannot be checked against detailed observations or laboratory tests.

The multiplicity of theories can be classified into four categories: (1) Ball lightning is formed by the separation of matter from bright channel of ordinary lightning; (2) ball lightning is formed by the excitation or combustion of some clump of matter (perhaps from the ground or from a tree) by normal lightning; (3) ball lightning is produced when fuel gasses in the atmosphere are ignited by a lightning stroke; and (4) ball lightning is produced as an electrical discharge by electromagnetic radiation emitted in an atmospheric process.  Theories in category (4) can be subdivided into those in which the energy source is within the ball and those in which the energy source is external.  For this column, I will limit myself to two of the many theories of ball lightning.

There are a number of theories in category (2) and (3) that focus on a chemical explanation of ball lightning.  The basic hypothesis is that a lightning strike creates an "aeronet", a fractal tangle of fibers that has very low density, approaching that of air at atmospheric pressure, and can therefore float rather than falling to the ground.  In part, this idea is motivated by observations of filamentary structure in lightning balls and the observation that dye molecules in electric fields can form spheres of fibers.  In a scenario proposed by Abrahamson and Dinniss, a lightning stroke produces a fiber network formed by chains of nanoparticles made of metal or metal compounds susceptible to oxidation.  The large surface area of such a network and the subsequent oxidation of the material are used to account for the glow and the energy release.

In my view, the serious problem with all such explanations, and indeed with all theories that fall into categories (1) through (3) above, is that in many instances ball lightning has been observed to pass easily through a glass window pane without damaging the glass.  At least for lightning balls with this capability, the passage through glass would seem to rule out any explanation that involves combustion of gas or self-confined plasmas or transport of glowing matter.

This leaves the theories in category (4), involving some form of electromagnetic process.  I find the most compelling of these to be the maser-caviton theory of Handel and Leitner, building on previous ideas of Kapitsza.  The basic idea is that the high electric field pulse accompanying a lightning stroke in a flat terrain can create a population inversion from the storage of energy in the rotational energy levels of water molecules.  The large atmospheric maser (i.e., laser for microwaves) thereby created can occupy a volume of several cubic miles and can last for many seconds.  This restless sea of stored energy can form an elaborate and irregular standing wave pattern which "spikes" in some locations.  At such a spike, the ball lightning discharge forms and is fed by the action of the maser, drawing energy from the entire maser volume.  The result is what is called a "soliton" of electromagnetic radiation, forming a hot cavity in the high-field region surrounded by a glowing plasma of ionized air.

This scenario fits many of the observations.  Such a soliton could pass through glass unimpeded, since only microwaves need to make the passage.  The observed irregular motions and interaction with conducting objects could be explained by the standing waves, because distant conducting objects (e.g., cars on a road outside or wind blown trees) should cause shifts in the standing wave patterns and move the spike of energy.  Similarly, the observed buoyancy in air is consistent, since there is no mass to support.  The reports of lightning balls entering structures like buildings and airplanes and doing little damage is also consistent, because the structure boundaries would restrict the maser volume from which the lightning ball could draw energy.

The problem with the Handel-Leitner theory is that it is difficult to test.  Production of cubic miles of population-inverted water molecules is not something readily done in the laboratory.  There have been demonstrations of 0.2 GHz microwaves after electrical discharges in moist air, but these results are only suggestive.  Perhaps a definitive confirmation of the theory might be supplied by detecting the presence of strong microwaves accompanying ball lightning.  However, the rarity of ball lightning events makes such an observation rather unlikely.

Are there SF implications for ball lightning?  As I said in the introduction, I've already used it in Twistor as a techno-prop to create a weak link between shadow universes, but it may have other uses.

I like the Handel-Leitner theory because of its SF possibilities.  One could imagine a weapon that harnesses the energy present in a thunderstorm to throw lightning balls at the opposition.  Or an alien planet that has a permanent population-inverted volume pumped by lightning or tidal forces, where ball lightning is a common occurrence, a normal part of the environment.  Or perhaps know phenomena like the Great Red Spot of Jupiter could be explained by maser action in the very active Jovian atmosphere.  In any case, there are likely to be further developments in this area.  I'll try to report them if and when they occur.

John G. Cramer's 2016 nonfiction book (Amazon gives it 5 stars) describing his transactional interpretation of quantum mechanics, The Quantum Handshake - Entanglement, Nonlocality, and Transactions, (Springer, January-2016) is available online as a hardcover or eBook at: http://www.springer.com/gp/book/9783319246406 or https://www.amazon.com/dp/3319246402.

SF Novels by John Cramer: Printed editions of John's hard SF novels Twistor and Einstein's Bridge are available from Amazon at https://www.amazon.com/Twistor-John-Cramer/dp/048680450X and https://www.amazon.com/EINSTEINS-BRIDGE-H-John-Cramer/dp/0380975106. His new novel, Fermi's Question may be coming soon.

Alternate View Columns Online: Electronic reprints of 212 or more "The Alternate View" columns by John G. Cramer published in Analog between 1984 and the present are currently available online at: http://www.npl.washington.edu/av .

References:

Ball Lightning Overviews

"Recently reported sightings of ball lightning . . .", J. Abrahamson, A. V. Bychkov, and V. L. Bychkov, Phil. Transactions of the Royal Society of London A 360, 11-35 (2002).

"Ball lightning - The scientific effort", Stanley Singer, Phil. Transactions of the Royal Society of London A 360, 5-9 (2002).

Ball Lightning Theories

"Ball lightning caused by oxidation of nanoparticle networks . . .", J. Abrahamson and J. Dinniss, Nature 403, 519-521 (2000).

"Development of the maser-caviton ball lightning theory", P. H. Handel and J-F. Leitner, Journal of Geophysical Research 99, 10,689-10,691 (1994).