The New Student's Reference Work/Whirlwind
Whirl′wind′, a small vortex motion of the earth's atmosphere, generally produced by the meeting of two contrary winds. Prof. R. W. Wood has shown a neat method of producing artificial whirlwinds. He heats a large iron plate — say four feet square — by placing a number of Bunsen burners underneath. While the plate is hot, a little sal-ammoniac is scattered over it. The fumes thus produced render visible the vortices formed by the two currents of air coming over opposite edges of the hot plate. See Cyclone and Storm.