Size Distribution, Crystal Form and Falling Velocity of Snow-Flake

[摘要] The size-distribution, falling velocity, and crystal form of snow-flakes were observed, mainly on those of graupel type. Observation for the size-disribution was made by the absorbing method using filter paper which was grounded by fine methylen-blue particles. The trace diameter of melted snow was transformed to equivalent water drop diameter. At the same time we took microphotograph of the crystal form. For observation of falling velocity, a dark box was made in which snow falling space was illuminated by a high pressure mercury lamp, and the traces of falling snow-flakes were taken by a camera in dotted lines, and then falling velocity was calculated from the length of the line. Some considerations were made on the result of these observations, and the followings are summarized: 1) The size-distribution of snow-flakes is shown in figure 8. 2) A number of small size particles (smaller than 0.25mm) related disconstruction of the snow-flakes. 3) If the each size is transformed to precipitation amount, 0.25_??_1.25mm is the most predominent part. 4) Frequency distribution for the falling velocity were shown in Figure 9 and 10. 5) Relation between the size of crystal and diameter of droplet is shown in Figure 11, 0.8_??_1.5mm graupel gathered along dw=0.499 ds line. where dw is the water droplet diameter and ds is the size of crystal. 6) There is no relationship between size of crystal and diameter of droplet in the particles smaller than 0.8mm in diameter.

[学科分类] 大气科学