Design of “Snow Crystal Sondes”

Abstract

A sampling and recording sonde, called a ?Snow Crystal Sonde,? was designed to observe the vertical distribution of snow crystals in a snow cloud. The shape of snow crystals was recorded on the surface of a circulating film coated with polyvinyl formvar solution during the ascent of the sonde. A radiosonde was released at the same time and place as the snow crystal sonde, in order to render a precise comparison between the snow crystal shape and the air temperature in the cloud. As the result of observation it was ascertained that Nakaya's Ta?s diagram was completely applicable to the growth of natural snow crystals. The snow crystal sonde was also found to be useful to measure the growth rate of snow crystals, and the space density of snow crystals and supercooled cloud droplets.