- a scale of wind forces, described by name and range of velocity, and classified as from force 0 to force 12, or, sometimes, to force 17.
- a scale of the states of sea created by winds of these various forces up to and including force 10.
- an international scale of wind velocities ranging for practical purposes from 0 (calm) to 12 (hurricane force). In the US an extension of the scale, from 13 to 17 for winds over 64 knots, is used
