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By Hamish Johnston
Ball lightning is a phenomenon in which a fiery sphere floats through the air near the surface of the Earth, usually during a thunderstorm. Or is it?
Although ball lightning is very rare, researchers have collected thousands of eyewitness observations from around the world, and there are even a few photographs of the fiery apparitions. While some researchers have been able to create glowing orbs in the lab, physicists haven’t really been able to explain why they occur in nature.
Well, maybe that’s because ball lightning exists in the brain of the beholder – at least some of the time.
That’s the conclusion of a report recently posted on the arXiv preprint server by Alexander Kendl and Joseph Peer at the University of Innsbruck. They argue that electromagnetic pulses emitted by lightning discharges could lead to the perception of “magnetophosphenes” by persons nearby.
Magnetophosphenes are luminous shapes that are perceived by people undergoing transcranial magnetic stimulation (TMS) – a technique used to stimulate brain activity using magnetic pulses.
Kendl and Peer have calculated that a person up to 100 m away from long-duration (1–2 s) repetitive lightning discharges would receive about the same dose as a TMS subject.
Although they admit that such lightning events are rare, they claim, “Lightning electromagnetic pulse induced transcranial magnetic stimulation of phosphenes in the visual cortex is concluded to be a plausible interpretation of a large class of reports on luminous perceptions during thunderstorms.”
Although I have never seen personally a globular lightning, my daughter (16 years old) and a dozen of her friends (16 to 20 years old) saw it last August 9th 2009 (she told me a couple of days after and thereafter I interviewed all those youngsters, having exactly the same description). The sight was in Noli (Liguria, Italy) at about 10.40 pm, the ball (like 100-200 W bulb, not very bright!) was floating in perfect weather (not any cloud nor even a breeze of wind, after a perfect weather day) 3-4 m from the sea surface (20-30 m or deeper at that point), 20 m outboards from a 30 m long peer (I think nobody else from the beach noticed it). The ball was 40 cm diameter slightly elongated vertically, floated gently (no wind! and no noise) without gaining any altitude for about 2 minutes; its color was more white at the edge and more reddish inside. I was told that their first comment was ‘somebody is burning something on the sea!’, but they immediately realized nobody was there: although all of them had phone, cameras and any kind of gadget, nobody took a movie or even a single snapshot! When the light disappeared my daughter claims (but she was 20 m from it) that she had the ‘feeling’ that something was falling on the sea surface.
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About 25 years ago, ball lightning was witnessed by a number of scientists, together and independently, at the Rutherford Appleton Laboratory. Until then, there was a widespread view that the phenomenon was either in the head or on the retina, but the shared experience by the people who witnessed that event convinced them that this was real. Not all of those who saw the ball lightning had experienced the same environment during its inception. I have also spoken to a number of people who have witnessed ball lightning in aircraft, and the Russians claim that they have lost several aircraft, some as a result of the ball entering the engine intake and at least one because a ball sat on the pilot’s chest inside the cockpit. These would be a very strange kind of hallucination.
There are two comprehensive review papers by B. M. Smirnov from the institute of High Temperatures, Russian Federation (Phys. Rep. Vol. 152 (4) 177-226 (1987), Phys. Rep. Vol. 224 (4) 151-236 (1993)). Many people have tried to explain them as plasma toroids, which must be particularly appealing to Alladio (as well as me). The trouble of course, is to be able to produce an electric discharge of this sort in the laboratory at atmospheric pressure, with a time-life of several seconds. The main question to answer, I think, is what keeps the plasma from recombining. The experiments which claim to reproduce ball-lightning in the laboratory last only a short time.
Observations of these phenomena in nature are only qualitative, unfortunately, although Smirnov tried to systemathise them.
I have never seen ball lightning, despite watching many thunder storms. If this phenomenon is in the observer’s head then surely its properties are different from an external event. Leonardo convinced people that sound was coming from a bell and not just occurring in the listener’s head by covering the bell. Surely if ball lightning is an internal event it will not go behind things. This fundamental difference must have been seen already, if it does show up, but observers might not have realized what they were seeing or its implication. I await reports from those lucky enough to see these things.
On a clear summer night 20 years ago my brother and I were star gazing. I was 6 yrs old and did not know what ball lightining was. My brother went down and left me on the roof for about 15 minutes when suddenly this strange orange ball of fire came next to me from nowhere. Being 6 yrs old I was about to touch it but as I was about to this ball of fire went up in the sky and vanished. Was this a hallucination? Absolutely not. I later told my brother that I saw a shooting star which came next to me but him being the mr know it all immediately knew this was a ball of lightining. I can still remember this very vividly even though 20 yrs has passed.