Experimental determination of collection efficiencies for small water droplets in air

This paper describes measurements of collection efficiencies for gravitational collisions between water drops of radius R = 30 to 55 μ and saline droplets of radius r = 1 to 12 μ. the results agree quite well with those obtained earlier by Picknett for drops of R = 30, 40 μ and also with the collision efficiencies computed by Hocking, Mason and Shafrir and Neiburger except that, for values of r / R < 0·1, the experimental values are consistently higher than the calculated values and fail to show the sharp cut‐off predicted by theory. the experiments support Hocking's prediction that drops of R ⩽ 18 μ will fail to collect droplets of smaller size.