On the Frozen Small Raindrops Observed at Syowa Station, Antarctica

Frozen small raindrops of drizzle size (a few hundred microns in diameter) were observed at a surface temperature of -12℃ on April 16 and July 2,1977 at Syowa Station (69.0°S, 39.6°E), Antarctica. The morphology and size distributions of these frozen raindrops were examined. The frozen particles were classified as having rugged surfaces, spikes, bulge and shattered, these were the same morphological features examined in laboratory experiments by TAKAHASHI (J. Meteorol. Soc. Jpn, 54,448,1976; ibid., 57,458,1979), but this time they were found in natural precipitation elements. The mean diameter of these raindrops was 180μm in both cases. Frozen small raindrops are considered to be produced by a coalescence of supercooled droplets in layer clouds, they froze after forming