Abstract
LONDON. Royal Meteorological Society, October 15.—Mr. C. J. P. Cave, president, in the chair.—L. F. Richardson: The brown corona and the diameters of particles. As a result of experiment the following variety of Airy's formula has been found to be in rough agreement with measurements on various holes and spheres: 5-3? 10-5 cm. (diameter of obstacle) · ((radius of chestnut? (radius of brown corona) source) In view of Ray's work this will not be applicable to the smallest cloud-droplets of 2 microns diameter; but is more likely to apply to drops of ordinary size of, say, 5 to 20 microns diameter.—L. F. Richardson: Photometric observations on clouds and clear skies. With an improved instrument made at Benson, it was shown that the difference-of-brightness at the moon's-limb, as measured by the instrument, is independent of the glow of the sunlit sky. It was also shown that the transparency of blue sky alters during twilight. Observations on clouds enable one to compute the rainfall equivalent to the cloud on those occasions when a corona reveals the size of the droplets; a certain very dark thunder-cloud was like a rain-factory holding in stock only one hour's output.—L. J. Sutton: Notes on haboobs. Haboobs are severe sandstorms of a type apparently confined almost entirely to the Sudan, where they are most frequent in the central region. Nearly all of them occur during the rainy season, i.e. May to October, and at Khartoum, for example, they are experienced more than once a week during this period and last about three hours on the average. Haboobs probably owe their origin to the heating up of a large region for four or five days, but owing to the wide distances between meteorological stations in the Sudan, it has not been possible to discover where any particular haboob originated or to follow its track.
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Societies and Academies. Nature 114, 666–667 (1924). https://doi.org/10.1038/114666b0
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DOI: https://doi.org/10.1038/114666b0