Ball Lightning

Ball lightning is described as luminescent spherical objects ranging from pea-sized up to several metres across, usually linked with thunderstorms. It is so rare that only about one in a million lightning strikes is thought to produce it, yet more than 10,000 written accounts exist. The Royal Meteorological Society describes it as a bright spherical object averaging about 25 centimetres, sometimes several metres across.

The earliest known account of ball lightning comes from the monk Gervase of Canterbury and dates to 1195, describing a fiery globe that descended from a dense cloud during a storm. An early English account uncovered in 2022 pre-dates the previous earliest English description by nearly 450 years. C&EN likewise places the oldest report at 1195 in England and notes that Georg Richmann was killed by a globe of fire in his Saint Petersburg laboratory.

Witnesses typically describe fist-size floating spheres of fire that spin, hover and sometimes explode, with most modern accounts far less dramatic than the 1638 church case. A recent European Severe Storms Laboratory record from 2022 logged a yellowish burning object with licking flames on a wavy path about 15 m above a road. Even with the spectrum in hand there is still no widely accepted explanation; hypotheses date back to the 1840s, when the English physician William Snow Harris first brought the phenomenon into science.

A literature review records the typical diameter of ball lightning as most commonly 10–20 cm (4–8 inches). A Cumbrian observer in July 2013 described a 60 cm glowing patch of grass followed by an orangey-yellow light passing right in front of her during a storm. Video of a 2012 event showed an apparent size of about 5 m across over ~15 m of travel.

The typical lifetime runs from one second to over a minute. Brightness flicker has been measured at about 100 Hz, possibly from a 50 Hz power line. Plasma explanations face a basic obstacle: hot plasma in air tends both to recombine and disappear and to rise away.

The vapour-silicon hypothesis holds that heat separates oxygen from soil silica, leaving pure silicon that condenses into a charged aerosol glowing as it re-oxidises. A silica hypothesis explains the glow as vaporized soil silica condensing into charged nanoparticles that burn, but cannot easily explain sightings inside aircraft. Aerosol theorists argue that fine particles react chemically and electromagnetically inside the ball, some picturing a radiant fluff ball of filaments.

The single published natural spectrum of ball lightning was captured by chance on the Tibetan Plateau in July 2012 during ordinary lightning research, while the team was photographing ordinary strikes. The observation was made with two slitless spectrographs at a distance of 0.9 km (900 m). The results appeared in Physical Review Letters on 17 January 2014.

The observed ball travelled at about 8.6 m per second and spanned roughly 5 m on camera. Its temperature was assessed as cooler than the parent lightning.

No explanation of ball lightning is widely accepted, and hypotheses about its nature reach back to the 1840s, when the English physician William Snow Harris first brought the phenomenon into science.

One family of explanations treats the ball as the afterglow of vaporized soil: lightning vaporizes silicate minerals, and the released silicon recombines into nanoparticles that glow as they oxidize in air.

A different line of reasoning holds that the rapidly changing magnetic field of a close lightning flash can excite neurons and so produce ball-like hallucinations.

Laboratory analogues include microwave fireballs, water-discharge fireballs, silicon-wafer arcs and plasma toroids that last only about 200 milliseconds.

Abrahamson and Dinniss proposed in 2000 that a strike on soil vaporizes silicon compounds and the resulting nanoparticle network glows as it oxidizes.

Interest in ball lightning has persisted for decades, sustained in part by the International Committee on Ball Lightning, which has run symposia on the subject since a 1988 meeting in Tokyo. The phenomenon under discussion is described as luminescent spherical objects ranging from pea-sized up to several metres across, usually linked with thunderstorms. Reports place its size anywhere from a golf ball to a small car, its duration from seconds to minutes, and its ending either in a gradual fade or in a violent explosion.

The observational record of ball lightning is thin, uneven, and largely anecdotal. The one published natural spectrum appeared in Physical Review Letters at the start of 2014 and was captured by chance during ordinary lightning research on the Tibetan Plateau during the summer of two thousand and twelve while the team was photographing ordinary strikes .

• 1195
  Earliest known account
  The monk Gervase of Canterbury describes a fiery globe descending from a dense cloud during a storm ^{1Turritopsis dohrnii · Wikipedia ↗}
• 1840s
  Entry into science
  The English physician William Snow Harris first brings the phenomenon into science ^{1Turritopsis dohrnii · Wikipedia ↗}
• summer of 2012
  Spectrum captured
  A team photographing ordinary strikes on the Tibetan Plateau records a spectrum by chance during ordinary lightning research
• start of 2014
  Spectrum published
  The one published natural spectrum appears in Physical Review Letters