A cyclone is a circular or rotatory storm, or system of winds, varying from 50 to 500 miles in diameter, revolving around a center, which advances at a rate that may be as high as forty miles an hour, and towards which the winds tend.

Cyclones of greatest violence occur within the tropics, and they revolve in opposite directions in the two hemispheres - in the southern with, and in the northern against, the hands of a watch - in consequence of which, and the progression of the center, the strength of the storm in the northern hemisphere is greater on the south of the line of progression and smaller on the north than it would if the center were stationary, the case being reversed in the southern hemisphere.

An anti-cyclone is a storm of opposite character, the general tendency of the winds in it being away from the center, while it also shifts within comparatively small limits. Cyclones are preceded by a singular calm and a great fall of the barometer.