A Photographic Rain Recorder for Studying Showers in Marine Air

Abstract

This recorder was designed primarily as a means for answering the following questions about shower rains: What is the duration and time of occurrence of showers, and how do these quantities vary from day to day over periods of many weeks? Emphasis in construction was placed upon recording frequently the occurrence or the absence of rains of a relatively low intensity, upon long periods of unattended operation remote from power sources, and upon portability. It had been shown that the standard recording rain gauges detect only about one-third of the showers of the type under study. The instrument developed detects even the very light showers, for it makes a photographic record each thirty seconds of most of the range of raindrop sizes which may be falling. Drops in the size range of 0.3 to 2.0 mm diameter can be photographically recorded on 120-m rolls of film over a period of five days without a servicing of the instrument. Rain records are presented illustrating the capacity of the instrument to do the job for which it was designed.