抄録
The measurement of electric charge on individual cloud particles of diameter larger than 15μw as carried out at the top of Mt. Teine in winter through the 1957 and 1959 seasons. The result obtained is described. The particles are classified into supercooled cloud droplets, frozen cloud droplets and ice crystal particles.
Only a small part of the number of supercooled cloud droplets was electrified, and the number of the droplets charged negatively was much more than that charged positively. About a half of frozen droplets was electrified, and the number of the droplets carrying negative charge was larger than that of those charged positively. The supercooled or frozen cloud droplets which were electrified were considerably larger than that of not electrified cloud droplets. Most of ice crystal particles was electrified. The magnitude of charge on the cloud droplets was roughly proportional to the mass of the droplets. Generally, the cloud droplets electrified intensely were observed only when clouds were active electrically and unstable colloidally.
Considering those results, it was proposed that the cloud droplets would be electrified by capturing the ions produced by point discharge during their growing process, therefore, the sign of charge on the cloud droplets is determined by the sign of electric field under the cloud base.
