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Ball Lightning Explained

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  • Jeroen Kumeling
    ... 100-watt ... a
    Message 1 of 1 , Feb 4, 2000
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      |http://www.discovery.com/news/briefs/brief2.html
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      |Ball Lightning Explained
      |Feb. 3, 2000 -- Ball lightning -- rare but dazzling spheres of bouncing
      |light -- may form with a poof when lightning strikes the Earth, say
      |scientists who propose a new theory to explain the phenomenon�s origins.
      |
      |Ranging in size from a golf ball to a soccer ball, ball lightning has been
      |reported during thunderstorms since the Middle Ages. As bright as a
      100-watt
      |lightbulb, an average ball lightning glows blue-white for about 10 seconds,
      |but can last up to a minute before exploding or disintegrating. Some hiss
      |like discharging power lines.
      |
      |Scientists estimate one out of a hundred people has seen one, although many
      |witnesses face disbelief.
      |
      |"They are for sure real," says Graham Hubler, a physicist at the Naval
      |Research Laboratory, who once saw ball lightning. "But they are so far out
      |of your experience, you don�t know what you�ve seen."
      |
      |One reason ball lightning is so mysterious is that scientists have been
      |unable to produce it in the laboratory. Until now, they assumed the orbs
      |formed out of thin air.
      |
      |But John Abrahamson of the University of Canterbury in New Zealand has a
      |more earthly explanation: When lightning strikes certain types of soils,
      |silicon in the earth vaporizes "like a smoker�s puff," then condenses into
      |tiny solid wires.
      |
      |A thousand times thinner than a human hair, these wires then coalesce into
      a
      |charged, ball-shaped network that glows when infiltrated by oxygen in the
      |air, according to the theory presented in this week�s journal Nature.
      |
      |One glowing sphere entered a woman�s house and hovered above her table�s
      |metal frame.
      |
      |"She could see within the ball lightning these chains, web-like structures
      |radially forming and reforming. This is very close to the theory that I�ve
      |put forward," says Abrahamson.
      |
      |His explanation far surpasses previous theories, according to Hubler. "I
      |believe his is the first model ever put forward that can explain nearly all
      |the features of ball lightning."
      |
      |The new theory is also testable. Abrahamson has found silicon in the soil
      |where lightning has struck. And lab experiments have produced tiny silicon
      |wires. He thinks they�ll successfully make a ball of lightning in the next
      |year.
      |
      |Efforts to understand these "ephemeral cotton-candy kind of things" still
      |suffer from lack of visible evidence, Hubler says, urging any readers who
      |have captured ball lightning on film to contact the researchers.
      |
      |By Emily Sohn, Discovery News Brief
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      |
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