Beaufort Scale

The Beaufort Scale is regularly used in weather forecasts, something of interest to all outdoor modellers.

Here is the standard table describing the wind speed and effects of the various levels of the scale.

Force	Description	Result	Wind speed
Force	Description	Result	mph	Knots
0	Calm	Smoke rises vertically	0-1	<1
1	Light air	Wind direction indicated by smoke but not wind vanes	1-3	1-3
2	Light breeze	Wind noticeable, leaves move, wind vane moves.	4-7	4-6
3	Gentle breeze	Leaves and small twigs in constant motion.	8-11	7-10
4	Moderate breeze	Wind raises dust and loose paper. Small branches are moved.	12-18	11-16
5	Fresh breeze	Small trees in leaf start to sway. Crested wavelets form on inland waters.	19-24	17-21
6	Strong breeze	Large branches in motion, wind whistles. Umbrellas used with difficulty.	25-31	22-27
7	Near gale.	Trees in motion, awkward to walk against wind.	32-38	28-33
8	Gale	Twigs break, hard to walk.	39-46	34-40
9	Strong gale	Some structural damage may occur, slates removed etc.	47-54	41-47
10	Storm	Trees uprooted, considerable structural damage.	55-63	48-55
11	Violent storm	Widespread damage.	64-72	56-63
12	Hurricane	Widespread damage.	72+	>63