On Bowen's Hypothesis

Abstract

Bowen (1953) examined daily rainfall at Sydney for January for the years 1859-1940, and found exceptional peaks to occur on the 12th and 22nd days of that month. He extended his investigations to other months and other stations, and concluded that there is a marked tendency for heavy falls of rain to occur on certain dates rather than on others and the pattern to be repeated year after year. He argued that if the feature is noticed in rainfall at a large number of stations over the globe the influence should be extraterrestrial. He put forward the now well-known hypothesis that on some calendar dates the Earth crosses a meteoric stream, and the meteoric dust entering the top of the atmosphere reaches the troposphere about 30 days later, to induce heavy rainfall, the influx of meteoric dust being supposed to provide the necessary condensation nuclei. He further strengthened his hypothesis by showing that such other occurrences as concentration of freezing nuclei counts, cirrus clouds, noctilucent clouds, and the dates on which snow first covered the ground at Tokyo all showed a tendency for maxima to fall on the preferred dates of singularity in a in all.