St. Elmo’s Fire Mimicked Using Rockets

Mysterious balls of lightning, sometimes called St. Elmo’s Fire, have now been mimicked by scientists using regular lightning borrowed from thunder clouds.

Using tethered rockets to trigger and direct lightning to the ground and through a wide variety of materials, lightning researchers at the University of Florida at Gainesville have managed to create some short-lived balls of fire that have a lot in common with the naturally-occurring floating balls of light.

The researchers hope that by recreating ball lightning they might get a better understanding of how it works.

“There are literally thousands of first-hand reports of ball lightning events,” said Dustin Hill, the lead author on a paper on the work which appears in the August issue of the Journal of Atmospheric and Solar-Terrestrial Physics. But because ball lightning is so unexpected and brief, there is virtually no scientific data on it.

“It’s certainly a mysterious phenomenon,” said Hill. “There is no hard evidence. There’s no quantitative data at all. It’s extremely subjective.”

Making even those first-hand reports less reliable is the fact that human perception is unreliable in these cases, said Hill. This is due to what’s called persistence of vision — the same thing that allows us to watch movies and not see them as a series of individual snapshots. The phenomenon makes a short-lived flash appear a lot longer than it actually is. The brightness of the balls also probably give the impression that the ball is much larger than it is, he added.

Hill isn’t questioning what people report. But as someone who has watched a lot of lightning and compared it to actual measurements, he knows the effect.

To try and see how regular lightning strikes might lead to floating balls of light, the researchers directed eight lightning pulses through a wide variety of materials.

“We tested roughly 100 different samples of materials,” said Hill. That list of materials was created with the help of physicists and other people all around the world.

The most successful materials they channeled lightning through were stainless steel and above pine tree wood. With this they managed to make small bright balls that lasted a fraction of a second. Stainless steel is not very likely to be the cause of ball lightning seen over the past several centuries — particularly in the centuries before stainless steel was invented.

Some previous laboratory experiments have also managed to ignite floating wisps of silicon into something that resembles ball lightning. The actual lightning experiments duplicated that effect repeatedly, said Hill.

These experiments point to one possible explanation of ball lightning: that it isn’t actually lightning at all. Rather, it is some material that has been vaporized and ignited by lightning. It burns briefly and then blinks out. But is it really ball lightning?

“What it demonstrates is that it is possible to produce luminous events at the surface that to an untrained observer looks like ball lightning,” said Richard Orville, professor and director of the Cooperative Institute for Applied Meteorological Studies at Texas A&M University.

In other words, the Florida researchers have not reproduced ball lightning, said Orville, nor have they claimed to. That’s because no one really knows what ball lightning is.