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Experimental measurements of the collection efficiencies of ice crystals in electric fields
Author(s) -
Latham J.,
Saunders C. P. R.
Publication year - 1970
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49709640808
Subject(s) - electric field , ice crystals , range (aeronautics) , materials science , analytical chemistry (journal) , atmospheric temperature range , chemistry , optics , thermodynamics , physics , composite material , chromatography , quantum mechanics
Abstract Experimental studies have been made of the aggregation of ice crystals of mean diameter about 5 μm upon an ice sphere of diameter 0.2 cm at the same temperature. The growth rate was found to be roughly independent of temperature over the range − 7°C to − 27°C and increased with electric field strength E to exceed the field‐free value by about 15 per cent, 40 per cent and 80 per cent in fields of 500, 1,000 and 1,500 V cm −1 respectively. At higher values of E the growth‐rate was reduced because of the ejection of clusters of ice crystals from the aggregate, probably under the influence of the intense electric forces. An appreciable amount of aggregation was observed at temperatures as low as − 37°C, in the presence or in the absence of electric fields. Absolute values of collection efficiencies at a velocity of 3 m s −1 were determined at the temperatures − 7°C, − 11°C, − 17°C and − 27°C. In the absence of an electric field collection efficiencies of about 0.3 were determined at all temperatures studied. Experiments with charged ice crystals indicated that electric fields increase the growth rate by increasing the adhesion efficiency and not the collision efficiency.