Although certain types of snow crystals may be detected with the naked eye, most of them are so tiny that their structural form cannot be determined without the aid of a microscope. If you chance to be out of doors during a snowfall, and happen to wear a dark coat of wool material, observe closely the flakes which chance to alight upon your sleeve and perhaps you may be able to recognise a true crystal.
When, as we sometimes remark, “Mother Goose is shaking out her feather bed,” and the white flakes come drifting down in large loose feathery flakes, then we may more readily discover a crystal without the aid of a glass. It is then that we find the lace-like, open, branchy and star-like shapes. These usually form during a local storm, or from a storm preceded by a warm wave. But the hard pellet-like crystals which sting our window-panes in falling, are from a very high altitude, and have been great travellers.
The study of the snow and its many mysterious phases is full of surprise and charm; and its various demonstrations fascinating and almost unexplainable. Among the many strange manifestations encountered in the kingdom of snow, perhaps there is nothing more mysterious than the so-called “snow rollers.” They are rather a recent discovery among snow students, and not frequently encountered. Two good examples of these curious rollers are given in photograph illustrations. The photographer came upon them quite unexpectedly and thought at first that the children had been amusing themselves by rolling huge snowballs. But upon investigation he discovered that these mysterious bundles of snow were quite hollow, like a large muff, and scattered at intervals over a large snow-covered field. These mysterious snow rollers form only after a light fluffy snowfall, followed by a rise in the temperature, from a degree or so above zero up to 36° or 38° above, accompanied by a peculiar stray gusty wind.
84. Clean cut prism-like crystal from high altitude
85. Suggesting a Masonic emblem. Trigonal crystal
86. The Egyptian crystal, because of its characteristic tracings
The rollers form most frequently in the foothill regions, wherein these gusty winds pour over and around the hilltops, and down across the valleys. After the temperature has reached 36° to 38° above and the snow upon the surface of the ground has been slightly dampened and rendered sticky, the capricious wind gusts scoop up here and there small particles of the moist snow, and overturn them upon that in front, forming a ridge or hollow arch, which is the commencement of the snow roller. Then the wind gets back of it, and proceeds to roll it forward, until, as it gradually rolls along it accumulates more snow, and increases in size, until it becomes too heavy a plaything for the sport of the winds, and then it stops.