Rensselaer Union, Volume 12, Number 3, Rensselaer, Jasper County, 2 October 1879 — Forms of Lightning. [ARTICLE]

Forms of Lightning.

Different forms of lightning are thus described by the Christian Union: A flash of lightning is a very large spark of electncity; just the same thing that one sees given by an electrical machine in a lecture on natural philosophy, the only difference being that the best machines will not give a spark more than a yard long, while some flashes of lightning have been estimated to be several miles in length. According to their appearance, various names have been given to these sparks in the sky, though in reality all the several kinds are one and the same thing. On a warm summer evening, one often sees the clouds on the horizon lit up with brilliant glows of lightning unaccompanied any sound of thunder. To this appearance the name of “heat lightning” has been given, and the warm weather is often assigned as its cause. In point of fact, the heat lightning is only that of a thunder-shower so far off that, while the observer can see the flash, no sound of thunder reaches him, and the intervening clouds veil and reflect the flash till it becomes a glow instead of the sharp streak usually seen, '

Where the flash, starting from one point, branches oat and divides into several parts, it has reoeived the name of “ forked lightning.” This is usuallyseen when the discharge is near the observer. Single flashes bearing a zigzag or crinkled aspect are denominated “chain or zigzag lightning,” probably from their resemblance to a chain thrown loosely on the ground. Again, when several discharges occur from about the same place at the same time, and are screened by rain or clouds, so as to fight up the heavens with a broad, bright glow, the title of “sheet lightning” is applied. These four comprise all the common forms. There is, however, one rare manifestation, called “ ball lightning.” In this phenomenon, a small globe or ball of apparent fire very slowly rolls along the ground, and after a time suddenly explodes, scattering destruction around. There are but few instances of this on record, and no very satisfactory explanation has ever accounted for this curious appearance.