A wind tunnel investigation on the riming of snowflakes. Part II: natural and synthetic aggregates.

Natural and artificial snowflakes have been rimed both in free fall and while suspended on a thin flexible fiber in the UCLA cloud tunnel. The results of these experiments show that during the early stage of riming, the motions exhibited by a riming aggregated do not affect the distribution of the rime accretion, in agreement with the observations of the riming behaviour of porous ice disks, reported in Part I of this study. It was also found that the collection kernel of a 10-mm diameter porous aggregate increased with respect to porosity at the same rate as that in Part I of this study. A discussion is presented of the free-fall behavior and the time evolution of the terminal velocities of riming aggregats.-Authors