The Diurnal Variation of Precipitation Frequency over Weather Ship M

The diurnal precipitation variation over northerly oceans is studied with the aid of the 3-hr synoptic observations from Weather Ship M at 66N, 02E during the 20-year period 1949–68. The precipitation frequencies possess a maximum in the morning during the whole year and a pronounced daytime minimum during the months March–September. The remaining months have a less pronounced diurnal variation and during September–April there is usually also an evening maximum. January and February even indicate a night minimum of precipitation frequency.