Accession Number : AD0758858

Title :   Freezing Water with Sized AgI Particles. Part II: Theoretical Considerations.

Descriptive Note : Technical rept.,

Corporate Author : ARMY ELECTRONICS COMMAND FORT MONMOUTH N J

Personal Author(s) : Gerber,Hermann E.

Report Date : MAR 1973

Pagination or Media Count : 34

Abstract : VELOPED FOR THE HETEROGENEOUS NUCLEATION RATE OF SUPERCOOLED WATER DROPLETS BY THERMALLY GENERATED AgI particles. The rate equations are determined as a function of the AgI particle size, shape, and surface structure, critical embryo shape, temperature, and ice-AgI contact angle in water. The assumptions and approximations inherent in this treatment are evaluated. It was determined that the important assumption of an appreciable nucleation rate is inconsistent with the large uncertainty in the value of the contact angle. As a consequence, classical theory could account for the experimentally determined dependence of activity on the particles' surface area. The appreciable nucleation rate also may not be used in Fletcher's ice-filled pits site theory. It is shown how the statistical nature of the nucleation process provides a method by which classical and site theory may be differentiated. (Author)

Descriptors :   (*NUCLEATION, SILVER COMPOUNDS), (*ARTIFICIAL PRECIPITATION, CONDENSATION), SUPERCOOLING, WATER VAPOR, IODIDES, FREEZING, PARTICLE SIZE, NUMERICAL ANALYSIS, THEORY

Subject Categories : Atmospheric Physics
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE