Time Dependent Characteristics Of The Heterogeneous Nucleation Of Ice

Download or read book Time-dependent Characteristics of the Heterogeneous Nucleation of Ice written by Macdonald Physics Laboratory. Stormy Weather Group and published by Macdonald Physics Laboratory ; Stormy Weather Group. This book was released on 1965 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dependence of heterogeneous nucleation of supercooled water drops on temperature and the duration of supercooling has been studied. The rain-sized drops were placed on an oiled aluminium surface and thermoelectric refrigeration was used to provide constant cooling-rates and to maintain constant temperatures. Once-distilled tap-water and melted snow and hail were investigated. Only the first two of these showed definite time-dependent properties. The experimental results are inconsistent with the hypothesis that all drops have equal probability of nucleation (stochastic hypothesis), and also with the hypothesis that the freezing temperature of a drop is the characteristic temperature of one of the impurities contained in the drop (''singular'' hypothesis). The results can be explained if the existence of a variety of nuclei is recognized, each of which is most likely to cause nucleation in a different range of temperatures, and if the nucleation probability associated with each impurity is a function of the temperature of the sample. (Author).