Observations with a directional raingauge

Abstract

Abstract An octagonal raingauge, which was set up to study the way in which rain impinged on vertical surfaces, is described. Observations made over a period of 12 years are analysed, showing that, in the London area, walls with moderate exposure to wind and facing approximately SW. receive most rain, equivalent to about 1/4 of the normal rainfall, and walls facing N. receive least, about 1/16 the normal rainfall. An equation connecting the mean incident angle of the rain on the ground with the wind speed is derived, and an attempt is made to obtain an indication of raindrop diameter.