Abstract
WITH this issue appears the first of a series of supplements which it is proposed to publish from time to time dealing descriptively with subjects of wide scientific interest. The present supplement is devoted to a discourse delivered at the Royal Institution on March 2 by Dr. G. C. Simpson, director of the Meteorological Office, and it provides in a convenient form a synopsis of existing knowledge of common meteorological phenomena. The method of dealing with the subject is characteristic of the present-day physicist, and it is essentially interesting. . Saturation and relative humidities are somewhat fully described, and this is followed by a discussion of condensation at temperatures above the freezing point. It is of interest to note that the number of nuclei present in the air varies from a minimum of about 100 per c.c. to 100,000 or 150,000 per c.c. at times in cities such as London and Paris. Condensation nuclei are formed in various ways, one being the household fires and factory chimneys which produce large quantities of nucleus-forming material, chiefly sulphurous oxide. In England something like 5000 tons of sulphur are burnt each day in coal fires, giving enough sulphur products to pollute the atmosphere of the whole of Great Britain. Haze and mist, though so much alike in appearance, appear to be fundamentally different, haze owing its origin to foreign matter and a small amount of water, while mist is due to an actual precipitation of water from vapour to liquid. On the other hand, there appears to be no fundamental difference between mist and fog, fog is generally only a dense mist. Above the fog temperature inversion prevents all upward motion of the air and the smoke made by large towns is kept fairly stationary and within a few hundred feet of the ground. Clouds, rain, thunderstorms, hail, snow, and other aspects of weather are so often topics of conversation that Dr. Simpson's authoritative discourse upon them will be welcomed by all scientific readers.
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Current Topics and Events. Nature 111, 507–510 (1923). https://doi.org/10.1038/111507a0
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DOI: https://doi.org/10.1038/111507a0