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Burn, Bang, Burp
Fri Mar 11, 2005
Listen in RealAudio 
Hi I'm Bryan Yeaton and this is The Weather Notebook. Ball lightning is usually seen
during thundery weather. Witnesses describe a floating globe, often about the size of a
basketball, and typically white or yellow -- sometimes with a bluish glow over the
surface.
It might last as much as a minute before either fading away or - sometimes --
exploding. Correspondent Allan Coukell takes you into the lab for some recent ball
lightning experiments.
Alan: The dancing, glowing spheres known as ball lightning are a scientific mystery.
The latest theory comes from John Abrahamson, of University of Canterbury in New
Zealand, who has been trying to create ball lighting in the high voltage lab. He calls his
theory the "bang, burp, burn bang" theory of ball lightning.
John Abrahamson: "The bang is the normal lightning strike, which you hear as
thunder."
Alan: It starts when ordinary forked lightning blasts the ground.
JA: "It goes underground, it goes through the soil. During that passage it heats the soil
intensely, vaporizing some of the soil."
Alan: The burp comes when the heat of expanding gases propels the hot soil vapour
into the air.
JA: "The burp [FX: Whoof] is the jet from beneath the soil."
Alan: A cloud of circulating gases and soot is formed. According to the theory, this then
begins to burn.
JA: "The material which condenses within that little sphere above the soil, that starts
burning in a special way. And that's the ball lightning."
Alan: The burning sphere might then exhaust its fuel and fade away [music fades] or it
might overheat and explode the final "bang" of the bang-burp-burn-bang theory of ball
lightning.
That's Allan Coukell of Auckland, New Zealand. The Weather Notebook is a production
of the Mount Washington Observatory and is underwritten by Subaru of America and
the National Science Foundation.
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