Abstract
During the period from August to September in 1954 the investigation of substances in raindrops and of aerosols in the air were made at several stations in the central part of Hokkaido. The results obtained are as follows.
(1) The size distribution of the particles is expressed by a formula dN/dr=kr-4 for the range of particle radius r below 10μ, and for the particles of r>10μ we have a formula dN/dr=k'r-5.
(2) The number of large hygroscopic nuclei in the air is about 500/m3.
(3) The number of large non-hygroscopic particles of radii larger than 15μ in the air is about 4000/m3 and it seems that these non-hygroscopic particles also serve as the nuclei of raindrops.
(4) The mass of non-hygroscopic particles in raindrops is considerably larger than that of hygroscopic particles.
(5) The larger non-hygroscopic particles are captured by raindrops more easily than the smalle_??_ ones.
