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No. 94: Jul-Aug 1994

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Flat-plate hail

Typical flat-plate hailston
Fig 1. A typical flat-plate hailstone from the May 17, 1993 fall.
May 17, 1993. Berkshire, England.

"As the cold front passed over Woodlands St. Mary, west Berkshire (183 meters above sea-level), at 1555 GMT, there commenced a 3-minute duration fall of unusual, flat-plate hailstones, measuring some 12 mm wide by 2 mm thick. These plates were smooth and glassy in appearance (indicating conditions of 'wet' growth) but not perfectly round, taking on an eccentric, wheel-like structure; with a 'hub' and four-spoke formation of transparent ice, having opaque areas in between."

(Anonymous; "Flat-Plate Hail -- 17 May 1993," Weather, 48:433, 1993.)

Comment. Other instances of hail platelets and small ice sheets may be found under GWP4 in Tornados, Dark Days. Ordering information here.

The spoke-like structure mentioned above, however, is most unusual. It is difficult to imagine a meteorological process that could create millions of hailstones -- all with this strange geometry.

From Science Frontiers #94, JUL-AUG 1994. 1994-2000 William R. Corliss