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No. 86: Mar-Apr 1993

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Cloud Plumes Natural But Still A Bit Anomalous

During the mid-1980s, satellites photographed strange cloud plumes that stretched hundreds of kilometers downwind of some nothern islands, especially Bennett Island, in the Soviet Arctic. Some wondered if perhaps the Soviets were conducting tests of some new type of weapon in these remote locations. With the end of the Cold War, flights of instrumented aircraft over the islands were permitted. Data from these flights support the idea that the mystery cloud plumes are formed by air currents passing over the islands. In other words, they are only orographic or mountaincaused clouds, like those sometimes seen over the Rockies.

But puzzles persist:

  1. Why are the plumes so long?

  2. Why do they form at such high altitudes -- more than 3 kilometers above the tops of the relatively small mountains on the islands?

(Monastersky, R.; "Mountains Give Rise to Perplexing Plumes," Science News, 141:422, 1992. Also: Fett, Robert W.; "Major Cloud Plumes in the Arctic and Their Relation to Fronts and Ice Movements," Monthly Weather Review, 120: 925, 1992.)

From Science Frontiers #86, MAR-APR 1993. � 1993-2000 William R. Corliss