Page:Popular Science Monthly Volume 16.djvu/313

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295
THE INTERNATIONAL WEATHER-SERVICE.

mind is lost in the effort to conceive the force which, in a day's time, can lift 50,000,000 tons! Yet, it would be easy to show that such figures, fabulous as they seem, do not adequately represent the cyclonic forces of a single storm. "The usual size of the cyclones in the Bay of Bengal," according to Piddington, "is from 300 to 350 miles; but," as he adds, "it would appear that they sometimes much exceed that extent"; and others give the average diameter as still greater than 350 miles. Now, in the passage of a cyclone over such a sheet of water, the vapor which has been slowly generated over its surface for many days is rapidly condensed and reconverted into water, and falls in the shape of torrential rains—as Dampier declared, "faster

PSM V16 D313 Horizontal air movements around northern hemisphere cyclone.jpg
Horizontal Movements of Air Around Center of Cyclone in Northern Hemisphere.— (Large arrow shows path of storm: smaller arrows, the winds taking a more radial direction, and increasing in velocity, as they near the center.)

than he could drink it." On the coasts of India, twenty inches have been known to fall in a single night; in the Bengal storm just mentioned, 15·2 inches fell in eighteen hours. Assuming that the mean