SEASONAL DISTRIBUTION OF RAIN. This is in many respects more important than the total annual quantity. It is the combination of rain fall, temperature, and sunshine that determines the character of the vegetation in each part of the globe. In the Northern Hemisphere some stations have a large rainfall in June and .July, when the sun is nearly overhead; but other sta tions have the minimum rainfall at this season. In the tropics most stations have two minima and two maxima of rainfall during the year. In the Southern Hemisphere, where the sun has its maximum power in December or January, even greater diversities appear. The growth of the perennial vegetation, and especially the annual plants and the important crops, is entirely. con trolled by. these relations of sunshine and rain. In regions where the rainfall is insufficient to perfect the important grain crops, recourse must be had to irrigation, the success of which again depends upon the annual distribution of snow and rain.
Various types of rain prevail over the ocean as well as over the land, although. unfortunately, we have but very few measurements of the actual rainfall at sea, and must. therefore, speck only of the frequency of the rain. Thus on the Atlantic and Pacific oceans. under or near the equator, is a rainy belt. where the pressure is always low. the winds exceedingly light, varia ble o• calm : here the sun almost invariably rises ill a clear sky, but about midday clouds begin to gather. and in a short time the whole face cf the sky is covered with dark clouds which pour down prodigious quantities of rain. Toward evening the clouds disappear: the sun sets in a clear sky, and the nights arc serene and fine. In latitudes 25° N. to 35° N. on
both Atlantic and Pacific there is a region of northeast trade winds in which the rainfall is comparatively light and occurs equally in all parts of the earth.
The details of the distribution of rainfall in the United States are given by Professor A. J. Henry in his ''Rainfall of the United States," Wm!her Bur«in Ti, 1897, and especially in the article, "Rainfall and Charts of Rainfall," in the Monthly Weather Ret'iciv for April, 1902 (Washington, D. C.).
Any bird popularly believed to foretell rain. Many of these birds are cuckoos. Both of the North American species have this reputation, as also have the black anis of Mexico and southward, which are fre quently called 'rain-crows.' In the middle west ern portion of the United States the bird com monly called 'rain-crow' is the yellow-billed cuckoo, The East Indian cuckoos, called 'koels' (q.v.)„ have the same reputation, and are com monly known in India and the Malay countries as 'rain•hirtis' and 'foretellers.' To what extent this repute is justified is a question admitting of discussion. Birds, as well as other animals, are no doubt sensitive to changes in the tempera tore and humidity of the air, and some may be quick to recognize that certain of these changes portend disagreeable weather. The immediate effect or their anticipations may lead them to make outcries indicative of discomfort or alarm. A great variety of information and folk-sayings on this subject is given in Dunwoody's "Weather Proverbs," Signal Serriee Notes, No. hr. (War Department, Washington, 1883). For Oriental superstitions, see Ibis (London, 1879).