Time lag in ice crystal nucleation in the atmosphere

Abstract

The nucleation of a supercooled cloud 'by atmospheric nuclei having a continuous range of nucleation temperatures is treated theoretically. A general expression is derived which, when applied to the observed distribution of atmospheric nuclei, sho'X'S that 20 - 50 % of the ice crystals produced form within the first few seconds, zehilst the remainder form at a gradually decreasing rate with an apparent time constant of about 6 minutes. There is no fundamental distinction betu:een prompt and delayed nuclei, and cold boxes IT'ith short measuring times give a correct picture of the nucleus content of the atmosphere. Show more