Beaufort Scale – Ursus Volans

Many kites, particularly those purchased from kite suppliers, are labelled with information as to the safe range wind speeds in which the kite can be flown. The figures are typically specified in Miles per Hour (mph), Kilometers per Hour (kph, km/h) or Beaufort wind speed (bft).

For the uninitiated, you might think having this information is a little bit pointless since not many of have wind speed meters, however in 1805 Sir William Beaufort came to our rescue when he invented the Beaufort Scale.

This empirical scale, allows us judge wind speed by simple observation of the environment. Initially purely through observation of sea conditions, the scale has been adapted for land use, making it ideal for kite flyers. The scale is typically stated as a range of forces from 0-12, however it can go a far as force 17 in areas regularly subjected to hurricanes and typhoons, but for kite flying purposes I have only listed forces 0-7 since above Force 5 things can get dangerous and rapidly out of control.

Beaufort Wind Scale	Mean Wind Speed		Limits of wind speed		Wind descriptive terms	Land Conditions	Kite Flying
bft	kph	mph	kph	mph
0	0	0	<1	<1	Calm	Calm. Smoke rises vertically.	Indoor and no-wind kites, Frisbees and R/C models. Drinking beer and shooting the breeze (outside if its warm)
1	4	2	1-6	1-3	Light air	Wind motion visible in smoke. Tips of branches and grass move slightly	Ultra light, soarer and delta kites.
2	9	6	7-11	4-7	Light Breeze	Wind felt on exposed skin. Leaves rustle and flags flap slowly	Lightweight and small medium sized kites. Some lifters and limited line laundry.
3	17	11	12-19	8-12	Gentle Breeze	Leaves and smaller twigs in constant motion. Light flags extend.	Ideal for all but the heaviest kites. Lifters with full lines of laundry.
4	24	15	20-29	13-18	Moderate Breeze	Dust and loose paper. Small branches begin to move.	Ideal for large, sparred kites (Box kites). Heavier lines and secure anchors for lifters.
5	35	22	30-39	19-24	Fresh Breeze	Smaller trees sway.	Strong, stable, high-wind kites using anchored lines. Exercise caution with lifters, double check anchors.
6	44	27	40-50	25-31	Strong Breeze	Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult.	If you have got kites up, now is the time to get help and walk them down.
7	56	35	51-62	32-38	Moderate Gale	Whole trees in motion. Effort needed to walk against the wind.	Indoor kites (indoors). Drinking beer and shooting the breeze.