The Measurement of Shower Rainfall Using an Airborne Foil Impactor

Abstract

Size spectra of raindrops are deduced from samples of shower rainfall obtained at cloud base during the course of a cloud seeding experiment. Estimates are made of the errors to be expected when an aircraft impactor is used a) to sample rain by making one pass through it, and b) to derive the total flow of water from a cloud using measurements made during repeated passes through rain from the cloud and assuming a particular cloud model. The sampling error in the total mow of water from a cloud is found to be about 14 per cent for the smaller clouds, failing to about 3 per cent for the larger ones, which is satisfactory for cloud seeding experiments.