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Science Frontiers ONLINE No. 40: Jul-Aug 1985 |
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Multiple Whirlwind Patterns
English meteorologists are spending some of the lazy summer days out in the countryside tracking down whirl wind patterns engraved on fields of wheat and other crops. One eyewitness account of the formation of a single spial pattern has been found. However, the multiple spiral patterns excite the most interest because of their geometric regularity. Between 1980 and 1984, eight quintuplet patterns have been found consisting of a large central circle and four smaller satellite circles. Triplets were also discovered. Although the origins of the multiplet patterns are still unexplained, some interesting generalizations have emerged:
1. The whirlwinds responsible for the flattened circles of crops have lifetimes of only a few seconds, whereas dust devils may persist for many minutes; 2. These whirlwinds seem to occur around evening time instead of during the heat of the day; and 3. They are all anticyclonic, while tornados are almost all cyclonic and true heat whirlwinds are split about evenly in their spin direction.
(Meaden, G.T.; "Advances in Understanding of Whirlwind Spiral Patterns in Cereal Fields," Journal of Meteorology, U.K., 10:73, 1985.)
 | Quintuplet circles found in a grain field near Cley Hill, England. |