Abstract
Sizes of about 54, 000 raindrops are measured for 249 observation periods of 9 rainfalls by filter paper method. Results are analysed according to the rainfall intensity of each period.
(1) Rainfall intensity R<1mm/hr
Graph of logarithm of raindrop number Nd (per cubic meter, per 0.1mm dropdiameter interval) against diameter d (mm) shows a parabola-like curve. The maximum of Nd occurs at 0.3 or 0.4mm diameter of drops. The curve resembles to the curve (e) of the model calculation by Mason and Ramanadham1).
(2) Rainfall intensity R between 1mm/hr and 8mm/hr
Number of raindrops larger than 1mm in diameter shows remarkable increase compared with the Marshall-Palmer distribution. The growing, process of the drops larger than 1mm in diameter seems to be different from that of the smaller drops.
