Accession Number : AD0623994

Title :   EXPERIMENTS ON THE NUCLEATION OF ICE 1961-63,

Corporate Author : MCGILL UNIV MONTREAL (QUEBEC) STORMY WEATHER GROUP

Personal Author(s) : Stansbury,E. J. ; Vali,Gabor

Report Date : AUG 1965

Pagination or Media Count : 27

Abstract : Results of recent nucleation experiments with raindropsized samples of distilled water, snow and hail were reported in MW-41 (Vali and Stansbury 1965). In the years 1961-63 similar experiments with less sophisticated equipment produced data on more than 20,000 freezing events. The work of MW-41 indicated that the dependence of freezing temperatures on cooling rate in the earlier experiments was small. The data has therefore been re-examined. For distilled water, the frequency distribution of freezing events with temperature has the shape predicted by the stochastic hypothesis. The mean freezing temperature of drops of distilled water increases by 1 degree when the volume is doubled. The behaviour of distilled water during and just following an interval at constant temperature is not predicted correctly by the stochastic hypothesis. For drops of natural precipitation the distributions cannot be described simply in analytical form: water from Alberta hail shows the warmest freezing temperatures, precipitation from Montreal freezes at somewhat colder temperatures. For drops formed from hail, the experiments suggest that the temperature of freezing is related to the specific nucleus content of the drops, and cannot be explained on a stochastic basis alone. (Author)

Descriptors :   (*NUCLEATION, ICE), (*ICE, NUCLEATION), FREEZING, SUPERCOOLING, HAIL, SNOW, WATER, PHASE

Subject Categories : Snow, Ice and Permafrost

Distribution Statement : APPROVED FOR PUBLIC RELEASE