Summary
A laboratory investigation of the charge acquired by a riming target, simulating a soft-hailstone, during collisions with ice crystals has shown that centrifugal acceleration of the target affects the magnitude and sign of the charge transferred when the acceleration exceeds a certain value. Above this critical value, which is dependent on the ambient temperature, the charging to the hailstone is positive under low liquid water content conditions whereas at lower rotational frequencies the charging is normally negative. During collisions with supercooled water droplets, no charging was observed at low rotational frequencies. However, at high frequencies, positive charging to the hailstone was detected at all temperatures. It is suggested that these spurious charging effects are due to the break-up of the rime ice on the target surface.
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Keith, W.D., Saunders, C.P.R. The effect of centrifugal acceleration on the charging of a riming hailstone. Meteorl. Atmos. Phys. 41, 55–61 (1989). https://doi.org/10.1007/BF01032590
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DOI: https://doi.org/10.1007/BF01032590