Whether or not ball lightning exists as a physical phenomenon is a question still under considerable debate. Our own Skeptoid has dug into the phenomenon in the past. A recently published paper brings new evidence into the debate. Let’s take a look!
The paper, Observation of the Optical and Spectral Characteristics of Ball Lightning by Jianyong Cen, Ping Yuan, and Simin Xue, was published last week in the Physical Review Letters of the American Physical Society. The researchers managed to capture video and spectrographs of a rare case of ball lightning while doing video captures of regular lightning. The paper itself is not available without buying it, but Philip Ball, a freelance writer with the American Physical Society, provides a good write up. His article also provides an image and the video of the ball lightning (with spectrograph) for us to view. Take a look.
The article describes ball lightning as:
Ball lightning typically appears during thunderstorms as a glow, ranging from the size of a golf ball to several meters across, which floats in the air for between one second and tens of seconds. There are many historical reports of such “fireballs” injuring or even killing people and setting buildings alight, and they have sometimes been given supernatural explanations.
It is noted that glowing plasma balls have been created in the lab via various mechanisms, but that these may or may not be representative of naturally occurring ball lightning. The article continues:
One popular theory is that ball lightning is caused when lightning striking the ground vaporizes some of the silicate minerals in soil. Carbon in the soil strips the silicates of oxygen through chemical reactions, creating a gas of energetic silicon atoms. These then recombine to form nanoparticles or filaments which, while still floating in air, react with oxygen, releasing heat and emitting the glow. If that’s so, one should expect to see atomic emission lines of silicon and other soil elements in the spectrum.
Happily, this observation included a spectrograph. Analysis of the spectrum revealed:
The researchers found that the spectrum contained several emission lines from silicon, iron, and calcium—all elements expected to be abundant in soil.
Bob Yirka of PhysOrg also reported on the paper. He writes:
The researchers report that they were not out to capture video of ball lightning, instead, they were video-taping lightning strikes as part of a genera research effort. As they were recording, a ball lightning event occurred right in front of their camera. They report that it came into being just off the ground, travelled for about five meters before rising slightly higher and traveling for another fifteen meters before disappearing. The entire event last just over a second and a half.
Interesting stuff. Be sure to check out the video on the APS site. The video is time expanded from 1.5 seconds (real time) to 10 seconds to make it more clear. While video evidence is compelling in many cases, the spectrographic evidence is very compelling in this case. It allows us to more easily rule out hoaxes, artificial light sources, and misidentified lights. While the questions of ball lightning are not yet settled, this evidence strongly argues for the reality of the phenomenon and gives pointers for further research.