An examination of the terminal velocity of falling snowflakes

Abstract

Falling snowflakes were photographed against a dark background by two cameras, one camera measuring the falling velocity, and the other measuring the size. Based on these results the microwave attenuation coefficients of sleet were calculated over a wide range of microwave frequencies and air temperatures. The terminal velocity of falling snowflakes is considered to be important in the interpretation of attenuation coefficients, particularly those of sleet snow-flakes. From the aerodynamic point of view, the terminal velocity of snowflakes is presumed to depend upon their size, shape and density. That is, we can express the terminal velocity of spherical snowflakes in terms of drag coefficient of snowflakes, gravitational acceleration and density of air.
We re-examined the drag coefficient of snowflakes, and made a trial at a new calculation. This paper presents the new method to calculate falling velocity of high density snowflakes. In the results, there was a good quantitative agreement between the observational and calculation results.