Friday, March 23, 2007

Fulgurites in Egypt shed light on past climate

"When lightning strikes sand or soil, it melts and fuses grains into features that some have called petrified lightning bolts. Their scientific name is fulgurites, after fulgur, the Latin word for lightning.
Fulgurites are branched, thin, hollow tubes usually 1 or 2 inches in diameter and a few feet to tens of feet long. They are rough on the outside (where sand grains and other material stick to the molten material) but glassy smooth on the inside, with many bubble holes produced by vaporized gases.
They usually are considered mere curiosities, but a recent bit of research reported in the Feb-
issue of the journal Geology put fulgurites to a scientific use, to obtain 15,000-year-old climate data.
About 65 lightning flashes occur per second worldwide, but lightning is not randomly distributed ? some areas get more than others.
One area that sees few storms is the Libyan Desert in southwestern Egypt."

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