Ball Lightning

Summary

Glowing spheres, usually the size of a grapefruit or a football, appear during thunderstorms. They drift. They pass through windows. They last a few seconds and then fade, or explode.

Thousands of people have reported them, including physicists, pilots and meteorologists, and for most of the twentieth century they were told they had imagined it.

Then in 2012, a team in China who were not looking for it happened to have a spectrograph pointed at the right patch of ground, and they got a spectrum. It shows silicon, iron and calcium.

Those are the elements of soil.

What is documented

The reports. Ball lightning has been reported for centuries, in large numbers, from many countries, by observers of every level of training. The typical account describes a luminous sphere between roughly ten and forty centimetres across, appearing during or immediately after a thunderstorm, persisting for a few seconds, moving horizontally, sometimes passing through a window or a wall, and ending either by fading or by exploding with a sharp report.

The dismissal. For most of the twentieth century the scientific position was that no such thing existed. The reports were attributed to afterimages, to hallucination, or to misperception of ordinary lightning.

There was a serious argument for that position, and it is worth stating. The phenomenon was never photographed, never measured, never reproduced, and never observed by anybody in a position to record it. Under those conditions, scepticism is not obstinacy. It is method.

The spectrum, obtained by accident. In July 2012, researchers from Northwest Normal University in Lanzhou were on the Qinghai plateau, using spectrographs and high-speed cameras to study ordinary cloud-to-ground lightning.

On 23 July, a strike came down, and out of the ground rose a luminous ball. It travelled roughly fifteen metres and lasted about one and a half seconds, and their instruments were already recording.

They had the first spectrum of natural ball lightning ever taken. It was published in Physical Review Letters in January 2014.

What was in it. The emission lines were of silicon, iron and calcium.

These are the principal constituents of soil. The ball was made of the ground it came out of.

Leading explanations

Vaporised silicon from the soil. Leading, and now supported by observation.

In 2000, John Abrahamson and James Dinniss published a mechanism in Nature. A lightning strike hits the ground and vaporises silica in the soil, reducing it to silicon in the presence of carbon. The silicon condenses into a network of nanoparticles, which forms a filamentary, aerogel-like ball, buoyant in air.

That ball then oxidises, slowly, back to silica. Oxidation releases energy, and it releases it gradually, which is why the object glows for seconds rather than milliseconds, and why it can end in a small explosion when the reaction runs away.

The 2012 spectrum is what this hypothesis predicts. Silicon, iron and calcium, in a ball, immediately after a ground strike.

Laboratory analogues. Luminous, long-lived plasma balls have been produced in the laboratory by several methods, including microwave cavity discharges and discharges over silicon wafers. These are not proof that natural ball lightning works the same way, and they demonstrate that the phenomenon is physically possible, which was not always conceded.

What is not accounted for. A great deal.

Ball lightning reported inside aircraft in flight. Ball lightning reported forming without any nearby strike. Ball lightning reported passing through a closed glass window without breaking it, which is difficult for a ball of hot silicon aerogel to do.

Some of these reports are probably misperception. Some may be a distinct phenomenon. And some may be magnetophosphenes: the strong, rapidly changing magnetic field of a nearby lightning strike can induce currents in the visual cortex and produce the perception of a moving luminous shape that is not there.

That last mechanism is real, is testable, and is not a way of calling witnesses liars. It means that some people who report ball lightning are seeing something, and that the something is inside their heads, and that they have no way of knowing the difference.

Current status

Partially explained. The phenomenon is real, has been spectroscopically recorded once, and has a plausible mechanism supported by that recording. The mechanism does not account for the full range of reports, and one measurement is one measurement.

The registry keeps this record beside AR-0057, and the pair should be read together. Sprites and ball lightning are the same story: a phenomenon reported for a century by people who were disbelieved, and then established, in a single stroke, the moment somebody finally had an instrument pointed at the sky when it happened.

In both cases the sceptics were right to be sceptical, and wrong about the thing.

Last reviewed: July 2026. Records are provisional. Where the evidence changes, the entry changes. Found an error? Tell us.