Abstract
The effect of horizontal drag forces on raindrop trajectories is shown to influence strongly the detection efficiencies computed for drop cameras and disdrometers. Two examples of sheared flow involving real instruments are studied and it is found that whereas detection efficiencies remain high for both large and small drops, low detection efficiencies occur for drops of radius near 0.2 mm. These predictions are tested against field results from one of the instruments and it is shown that the theory of Rinehart is inadequate for small drops for this instrument.
