The Beaufort scale was long in use as a system for estimating wind speeds. It was introduced in 1805 by Admiral Sir Francis Beaufort (1774-1857) of the British navy to describe wind effects on a fully rigged man-of-war sailing vessel, and it was later extended to include descriptions of effects on land features as well.

0Smoke rises vertically and the see is mirror smoothcalm0000
1Smokes moves slightly with breeze and shows direction of windlight air1-31-51-3<2
2You can feel wind on your face and hear the leaves start to rustlelight breeze4-66-114-72-3
3Smoke will move horizontally and small branches start to sway. Wind extends a light flaggentle breeze7-1012-198-124-5
4Loose dust or sand on the ground will move and larger branches will sway, loose paper blows around, and fairly frequent whitecaps occurmoderate breeze11-1620-2813-186-7
5Surface waves form on water and small trees swayfresh breeze17-2129-3819-248-10
6Trees begin to bend with the force of the wind and causes whistling in telephone wires and some spray on the sea surfacestrong breeze22-2739-4925-3111-13
7large trees swaymoderate gale28-3350-6132-3814-16
8twigs break from trees, and long streaks of foam appear on the oceanfresh gale34-4062-7439-4617-20
9branches break from treesstrong gale41-4775-8847-5521-24
10weak trees are uprooted, and the sea takes on a white appearancewhole galem48-5589-10256-6425-28
11widespread damagestorm56-63103-11765-7329-32
12structural damage on land and storm waves at seahurricane>46>118>74>33