On the Drop Size of Rain from Clouds Formed of Water Particles alone

Studies on the Formation of Cloud and Rain IV

Abstract

In order to study how rain drops of large size are produced in clouds formed of water particles alone, we observed the drop size of rain and compared it with the state of cloud which was determined from upper air soundings.
It is usually believed that only small drops can be produced in clouds which contain no ice crystals and that the diameter of the largest drop produced in them is about 0.5mm. From our observations, however, it was found that almost in all cases drops as large as 1.5mm were produced in such clouds.
Thus, we can surmise that in low latitudes drops larger than we observed may be formed without ice crystals. We further made some considerations on the formation of such large drops in water clouds.