Weather – Wind roses Explained


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.



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.




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. Gale pennant.svg
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. Gale pennant.svg
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. Gale pennant.svg
Gale pennant.svg
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). Gale pennant.svg
Gale pennant.svg
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. Storm warning.svg
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. Storm warning.svg
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. Storm warning.svg

Storm warning.svg