Radar Echo Structure of Middle-Level Precipitating Clouds and the Charge of Raindrops (II)

Change of Electrical Properties of Raindrops

Abstract

Electrical properties of raindrops originated from middle-level precipitating clouds were studied on the basis of the simultaneous observations of the charge on raindrops and the structure of RHI radar echoes.
Main results are as follows: Raindrops with large positive charge were observed only when the intensive echo-regions in the streaks from generating cells passed over the site of observation. Except for the raindrops with large positive charge, large and small raindrops from middle-level clouds tended to be charged negatively and positively, respectively. The amount of charge on raindrops originated from warm rain clouds was smaller than that from middle-level clouds. It was inferred that the amount of charge on precipitation particles from middle-level clouds was not changed when the particles fell through low-level convective clouds.