Beaufort wind scale
Wind force by knots with the classic sea-state descriptions.
| Force | Knots | Name | Sea state |
|---|---|---|---|
| 0 | <1 | Calm | Sea like a mirror |
| 1 | 1–3 | Light air | Ripples without crests |
| 2 | 4–6 | Light breeze | Small wavelets |
| 3 | 7–10 | Gentle breeze | Large wavelets, scattered whitecaps |
| 4 | 11–16 | Moderate breeze | Small waves, fairly frequent whitecaps |
| 5 | 17–21 | Fresh breeze | Moderate waves, many whitecaps |
| 6 | 22–27 | Strong breeze | Large waves, extensive foam crests |
| 7 | 28–33 | Near gale | Sea heaps up, foam streaks |
| 8 | 34–40 | Gale | Moderately high waves, spindrift |
| 9 | 41–47 | Strong gale | High waves, dense foam |
| 10 | 48–55 | Storm | Very high waves, white sea surface |
| 11 | 56–63 | Violent storm | Exceptionally high waves |
| 12 | 64+ | Hurricane force | Air filled with foam and spray |