|
Force |
Wind Speed
MPH/Knots |
Wave Height
(feet) |
Designation |
Description |
| 0 |
<1 |
<1 |
0 |
Calm |
Smoke rises vertically. Tree leaves do not move. Sea mirror calm. |
| 1 |
1-3 |
1-3 |
Ripples |
Light Air |
Smoke drift indicates wind direction. Weather vane does not move. Ripples but without foam crests |
| 2 |
4-7 |
4-6 |
0 to 4" |
Light Breeze |
Wind felt on face. Weather vane begins to move. Leaves rustle. Small wavelets. Crests do not break. |
| 3 |
8-12 |
7-10 |
4" to 1' 8" |
Gentle Breeze |
Winds extends light flags. Leaves and twigs in constant motion. Large wavelets. Perhaps scattered whitecaps. |
| 4 |
13-19 |
11-16 |
2-4 |
Moderate Breeze |
Dust and loose paper raised. Small branches move. Small waves. Fairly frequent whitecaps. |
| 5 |
20-24 |
17-21 |
4-8 |
Fresh Breeze |
Small trees sway. Moderate waves. Many whitecaps. |
| 6 |
25-31 |
22-27 |
8-13 |
Strong Breeze |
Large branches move. Wind whistles in wires. Large waves begin to form. White foam crests. Probably spray. |
| 7 |
32-38 |
28-33 |
13-20 |
Moderate Gale |
Whole trees move; Walking affected. Sea heaps up and white foam blown in streaks along the direction of the wind. |
| 8 |
39-46 |
34-40 |
13-20 |
Fresh Gale |
Twigs break off trees. Walking difficult. Moderately high waves. Crests begin to break into spindrift. |
| 9 |
47-54 |
41-47 |
13-20 |
Strong Gale |
Slight structural damage occurs. Branches break. High waves. Dense foam along the direction of the wind. Crests of waves begin to roll over. Spray may affect visibility. |
| 10 |
55-63 |
48-55 |
20-30 |
Whole Gale |
Trees uprooted. Considerable structural damage. Very high waves with overhanging crest. The surface of the sea takes a white appearance. The tumbling of the sea becomes heavy and shock like. Visibility affected. |
| 11 |
64-73 |
56-63 |
30-45 |
Storm |
Widespread damage. Extremely high waves. The sea is completely covered with long white patches of foam lying in the direction of the wind. Visibility affected. |
| 12 |
74+ |
64+ |
45+ |
Hurricane |
Severe and extensive damage. The air is filled with foam and spray. Sea completely white with driving spray. Visibility very seriously affected. |
| 1 KNOT=1.15 MPH / 1 MPH=.87 KNOTS |
|