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Electrical corona from ice hydrometeors
Author(s) -
Griffiths R. F.,
Latham J.
Publication year - 1974
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.49710042404
Subject(s) - corona (planetary geology) , thunderstorm , lightning (connector) , corona discharge , mechanics , electric field , range (aeronautics) , atmospheric sciences , materials science , meteorology , physics , geology , voltage , thermodynamics , power (physics) , quantum mechanics , venus , composite material , astrobiology
In contradiction to earlier work it has been found that substantial corona currents can be initiated from ice surfaces over a wide range of conditions. Measurements have been made of the critical fields required to initiate corona from ice particles a few millimetres in length suspended in a uniform electric field. The variables included size, shape, purity, orientation and the surface features of the particles, their initial charge, pressure and temperature. Currents of about 0.1 μA at onset were obtained and the details of the forms of discharge and associated currents were determined as a function of applied field. A particularly interesting finding was that substantial corona currents were obtained only at temperatures higher than −18°C. A semi‐quantitative explanation of these results is given in terms of the surface conductivity of ice. The characteristics of the streamers observed have been related to the Dawson‐Winn model as extended by Phelps. In view of these new results it is suggested that the role of corona from ice hydrometeors in a thunderstorm is of much greater importance than has previously been realized, particularly in connection with the initiation of lightning and the enhancement of ionic conductivity; the onset fields for corona emission from ice in the central regions of thunderclouds are probably in the range 400 to 500 kV/m.