Science: Reviewing Scud

Ever since cloud-seeding began (TiME, Aug. 28, 1950), the scientific rainmakers have been haunted by a stimulating worry. They feared—or hoped—that their Dry Ice and silver iodide might do more than wring the water out of local masses of susceptible clouds. Rainmaking might possibly start meteorological chain reactions, conjure up violent storms, bring blizzards whistling down from Canada, or even beckon hurricanes off the open sea. This possibility had a military angle: timely cloud-seeding from a safe distance might mess up the weather of an enemy country. Last week Meteorologist Dr. Jerome Spar of New York University laid this interesting ghost, or at least cut it down considerably, by reporting on the lack of success of the Navy’s recently declassified “Project Scud.” While maintaining a neutral position, Dr. Spar agreed that the thing should be tried. Backed by the Office of Naval Research, he organized a two-year experiment that covered the U.S.’s eastern seaboard. During the periods of January to April 1953 and December 1953 to April 1954, Dr. Spar and his assistants at New York University selected 37 “meteorological situations.” Ten hours ahead of the time that they thought the clouds would be ripe for seeding, they telephoned Norfolk, Va. When zero hour came, three planes flew parallel tracks, dropping trails of Dry Ice. Simultaneously, 17 ground generators, from Tampa, Fla. to New York City, filled the air with silver iodide particles. Guided by chance, the Norfolk seeders reserved 19 of the 37 situations as “controls,” which were left unseeded. The meteorologists were not told which clouds were left unseeded. Both the ravished and the virgin situations were studied carefully. The verdict : “No evidence of large-scale meteorological effects due to seeding.” Dr. Spar does not insist that cloud-seeding has no local effects. He is convinced that Project Scud has proved that large-scale weather is not sensitive to man-started chain reactions. Not all meteorologists will accept this conclusion. Vincent Schaefer, developer of Dry Ice cloud-seeding, says that Project Scud proves only that seeding of one type produces no startling results. It does not prove that other efforts would be ineffective His former boss, Nobel Prizewinner Irving Langmuir, asked to participate in Project Scud, but was refused.