Contents

14 September 1973
Vol 181, Issue 4104

About The Cover

(Upper Left) Optical effects produced by water droplets in a cloud photographed 10 minutes prior to seeding with silver iodide. After artificial seeding, optical effects produced by ice crystals appeared (upper right and lower left and right). See page 1043. [Photographs, upper left and right, P.V. Hobbs and L.F.Radke Atmospheric Sciences Department, University of Washington, Seattle; photographs lower left and right, F.M. Turner, University of Washington]