Microcinematographic Studies of Contact Nucleation

Abstract

Water drops of 2 mm diameter were supercooled on a glass slide, sprayed with AgI particles, and photographed at low magnification with a 16-mm movie camera at a speed of 64 frames per second to determine the nature of freezing by contact nucleation. In each case; nucleation was initiated at the point of particle contact and continued over the entire surface of the drop. The interior of the drop then froze toward the center at a much slower rate. The surface structures and crystallization rates by contact nucleation compare favorably with those found by other workers where water was frozen in containers.