An experimental test of theoretically calculated collision efficiencies of cloud drops

An experimental method was devised for testing theoretically calculated collision efficiencies of cloud drops. The experiment was carried out with drops of radii A ranging between 35 and 95 μ which collided and coalesced with smaller drops of radii a corresponding to values p = a/A which ranged between 0.47 and 1.00. It was found that the experimental results were consistent with the theoretical calculations of Shafrir and Neiburger for the case that 38 ≤ A ≤ 95 μ and p ≤ 0.90 and with the theoretical calculations of Neiburger for the case that A ≥ 70 μ and p > 0.90. For the case that A < 60 μ and p > 0.90, our experimental results deviated from the theoretical ones in that at p = 1 the theory predicted zero collision efficiencies, whereas experimentally it was found that the collision efficiency was non-zero.