Research Article
Jun 1970
Arizona Weather Modification Research Program
Publication: Journal of the Irrigation and Drainage Division
Volume 96, Issue 2
Abstract
The paper presented here is an interim progress review for the period ending with the fourth summer season at Flagstaff. In 1967, randomized seeding of isolated cumulus clouds was the main experiment. A simple computer model served successfully for test cloud selection, and evaluation of the results. This experiment demonstrated statistically significant cloud-top height increases averaging 6,000 ft and approximate doubling of precipitation. Cloud interiors were probed with an instrumented aircraft. In contrast to events in unseeded clouds, the observations in seeded cumuli showed rapid spread of glaciation throughout the clouds. Subsequently, additional buoyancy and organization of the upcurrent, and early shutting off of precipitation growth were noticed. The study in 1967 also involved exploratory trials with the seeding of larger storm systems, in order to organize and stimulate them. In 1968, a program called COOP II brought together the capabilities of several groups to continue the studies with special emphasis on the storm systems and on the optimizing of seeding techniques.
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Published In
Journal of the Irrigation and Drainage Division
Volume 96 • Issue 2 • June 1970
Pages: 103 - 110
Copyright
© 1970 American Society of Civil Engineers.
History
Published in print: Jun 1970
Published online: Feb 11, 2021
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Authors
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Paul B. MacCready Jr.
Pres., Meterology Research, Inc., Altadena, Calif
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