It has not until quite recently been possible to measure with any degree of accuracy, and photograph raindrops in the exact size in which they fall. But now that it has become possible to do this, it is most interesting to know the process. It is also most important to be able to know that certain types of raindrops fall during given storms. For instance, a very large type of raindrop emanates from a violent thunder-storm, when there is vivid lightning. Another distinct type belongs to the general storm, and there are many others, their form and size being governed entirely by the clouds and the character of the storms from which they fall.
Hundreds of samples of raindrop impressions have recently been secured, and the method employed to collect and photograph them is most unique. To secure these raindrop impressions, emanating from various storms and clouds, a shallow tin receptacle about four inches in diameter was used, the bottom of the tin being covered with fine, uncompacted flour an inch deep. The flour was then exposed to the rain for about four seconds, and the raindrops allowed to remain in the flour until each drop had hardened as it fell. These dough pellets, or raindrop impressions were found, in every instance, to correspond very closely in size to the raindrops as they fell. When thoroughly dried out they were carefully removed from their bed of flour, labelled and photographed. This method of determining the relative dimensions of raindrops which fall during various types of storms, has proven to be the most satisfactory method as yet discovered.
142. Beautiful type of window-ice growing like delicate sea-weed
143. Window-pane ice. Resembling pampas grass
144. Another type of window-pane ice
The large raindrops are invariably great travellers. The larger the drops the greater the height from which they fell. Some of them travel a distance of five to eight miles before reaching the earth.
Raindrops falling from very high altitudes invariably start out as snowflakes, as the upper section of a rain-cloud, when formed in the high frigid altitudes, is usually composed of snow. The general rain-storm usually furnishes small to medium-sized drops. But sudden thunder-storms, where the clouds gather in dense, mountain-like formations, as the one shown in the photographed illustration, furnish the very largest raindrops which fall, unless we except those which may sometimes result from the melting of large hailstones, which emanate sometimes from very violent storms of the whirling, tornado type.