On the Probabilistic Analysis of Precipitating Cells Defined by the Spatial Concentration of Falling Snow Particles

摘要

Photographic observations were carried out on the spatial concentration of falling snow particles. Photographs were taken by 8 mm cine camera at the rate of 16 frames a minute. The main results are described as follows :1) The frequency of each concentration which is classified by 10-particle difference, was obtained in the shower and continuous types of snowfall. The distribution curve of frequency may be explained from a general compound Poisson's distribution in the case of shower, while it is represented approximately as a Gaussian distribution in the cese of continuous one.2) In the case of snow shower, the probability density function of cells that their average spatial concentration lies between λ and λ+dλ was obtained, where λ is the concen-tration averaged on each cell. It may be thought that the probability distribution function consists of two curves : one of them has a steeper and larger maximum value than the other one, which may be thought Gaussian distribution in form, at low concentration. This result illustrates that the former corresponds to the distribution curve of original cells and the latter is due to snow particles blown down from neighbouring trees and roofs of huts.3) Auto-correlations were calculated from the fluctuation of spatial concentration in both cases.