EXPLANATION OF WIND ROSES:

The wind roses in blue color are located in the center of each 5° square on the surface of the Earth
Each rose shows the distribution of the winds that have prevailed in the area over a considerable period of time.
The wind percentages are summarized for calm and for the Cardinal and Inter cardinal compass points.
The arrows fly with the wind,indicating the direction from which the wind blew. |
The length of the shaft, measured from the outside of the circle to the end of the visible shaft (not necessarily to the end of the last feather), using the appropriate scale below, gives the percentage of the total number of observations in which the wind has blown from that direction.
The number of feathers shows the average force of the wind on the Beaufort scale. The figure in the center of the circle gives the percentage of calms. When the arrow is too long (over29 percent) to fit conveniently in the 5° square, the percentage is indicated numerically on the shaft.

FOR EXAMPLE:

The sample wind rose should be read thus:
In the reported observations the wind has averaged as follows:

N. 32 percent, Beaufort force 5;
N.E. 11 percent, Beaufort force 4;
E. 8 percent, Beaufort force 4;
S.E. 4 percent, Beaufort force 4:
S. 3 percent, Beaufort force 4 ;
S.W. 5 percent,Beaufort force 4;
W. 10 percent, Beaufort force 4;
N.W. 25 percent, Beaufort force 4;
Calms 2 percent.

SCALE OF WIND PERCENTAGES:

 

BEAUFORT SCALE

SCALE	DESC.	SPEED	WAVE HEIGHT	CONDITIONS	ON LAND	FLAG WARNING
0	Calm	< 1 knot < 1 mph < 2 km/h < 0.5 m/s	0 ft (0 m)	Sea like a mirror	Smoke rises vertically.
1	Light air	1–3 knots	0–1 ft	Ripples with appearance of scales are formed, without foam crests	Direction shown by smoke drift but not by wind vanes.
		1–3 mph
		2–5 km/h	0–0.3 m
		0.5–1.5 m/s
2	Light breeze	4–6 knots	1–2 ft	Small wavelets still short but more pronounced; crests have a glassy appearance but do not break	Wind felt on face; leaves rustle; wind vane moved by wind.
		4–7 mph
		6–11 km/h	0.3–0.6 m
		1.6–3.3 m/s
3	Gentle breeze	7–10 knots	2–4 ft	Large wavelets; crests begin to break; foam of glassy appearance; perhaps scattered white horses	Leaves and small twigs in constant motion; light flags extended.
		8–12 mph
		12–19 km/h	0.6–1.2 m
		3.4–5.5 m/s
4	Moderate breeze	11–16 knots	3.5–6 ft	Small waves becoming longer; fairly frequent white horses	Raises dust and loose paper; small branches moved.
		13–18 mph
		20–28 km/h	1–2 m
		5.5–7.9 m/s
5	Fresh breeze	17–21 knots	6–10 ft	Moderate waves taking a more pronounced long form; many white horses are formed; chance of some spray	Small trees in leaf begin to sway; crested wavelets form on inland waters.
		19–24 mph
		29–38 km/h	2–3 m
		8–10.7 m/s
6	Strong breeze	22–27 knots	9–13 ft	Large waves begin to form; the white foam crests are more extensive everywhere; probably some spray	Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.
		25–31 mph
		39–49 km/h	3–4 m
		10.8–13.8 m/s
7	High wind, moderate gale, near gale	28–33 knots	13–19 ft	Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind; spindrift begins to be seen	Whole trees in motion; inconvenience felt when walking against the wind.
		32–38 mph
		50–61 km/h	4–5.5 m
		13.9–17.1 m/s
8	Gale, fresh gale	34–40 knots	18–25 ft	Moderately high waves of greater length; edges of crests break into spindrift; foam is blown in well-marked streaks along the direction of the wind	Twigs break off trees; generally impedes progress.
		39–46 mph
		62–74 km/h	5.5–7.5 m
		17.2–20.7 m/s
9	Strong/severe gale	41–47 knots	23–32 ft	High waves; dense streaks of foam along the direction of the wind; sea begins to roll; spray affects visibility	Slight structural damage (chimney pots and slates removed).
		47–54 mph
		75–88 km/h	7–10 m
		20.8–24.4 m/s
10	Storm, whole gale	48–55 knots	29–41 ft	Very high waves with long overhanging crests; resulting foam in great patches is blown in dense white streaks along the direction of the wind; on the whole the surface of the sea takes on a white appearance; rolling of the sea becomes heavy; visibility affected	Seldom experienced inland; trees uprooted; considerable structural damage.
		55–63 mph
		89–102 km/h	9–12.5 m
		24.5–28.4 m/s
11	Violent storm	56–63 knots	37–52 ft	Exceptionally high waves; small- and medium-sized ships might be for a long time lost to view behind the waves; sea is covered with long white patches of foam; everywhere the edges of the wave crests are blown into foam; visibility affected	Very rarely experienced; accompanied by widespread damage.
		64–72 mph
		103–117 km/h	11.5–16 m
		28.5–32.6 m/s
12	Hurricane force	≥ 64 knots	≥ 46 ft	The air is filled with foam and spray; sea is completely white with driving spray; visibility very seriously affected	Devastation.