Beaufort wind scale
The Beaufort wind scale is a range of numbers from 0 to 17 representing the force of winds, together with descriptions of the corresponding land and sea effects. The Beaufort number 0 means calm wind less than 1 kilometer per hour (0.62 mph), with smoking rising vertically. Beaufort 3 means light breeze, 12–19 km/h (8–12 mph), with leaves in constant motion. Beaufort 11 is a violent storm, 103–117 km/h (64–72 mph) and Beaufort 12 is a hurricane 118+ km/h (73+ mph) with devastation. Beaufort 13–17 indicates the force of the hurricane.
The scale is named after its inventor, Admiral Francis Beaufort (1774–1857).