1.Calm or Force Zero Calm or zero wind: the wind speed is below 1 knot (Knot). When there is no wind, the sea surface is as smooth as a mirror.

2. Light Air or Force One: The wind speed is between 1 and 3 knots. After soft winds continue to blow for a period of time, the wave height will still be around 0.1 meters (0.25 feet), but there will be many ripples (ripper) on the sea surface.

3. Light Breeze or Force Two: Wind speed between 4 and 6 knots. After the light wind continues to blow for a period of time, numerous small waves (Small Wavelets) that are like fish scales but will not break will appear on the sea surface. The wave height is between 0.2-0.3 meters (0.5-1 feet). If it is illuminated by sunlight or moonlight, the sea will appear sparkling.

4. Gentle Breeze or Force Three: Wind speed between 7 and 10 knots. After the breeze continues to blow for a period of time, large waves (Large Wavelets) with wave heights ranging from 0.6 to 1 meter (2 to 3 feet) will appear on the sea surface. The heads of some water waves will begin to break, resulting in sparse patches on the sea surface. A small white cap wave appears.

5. Moderate Breeze or Force Four: Wind speed is between 11 and 16 knots. After the gentle wind continues to blow for a period of time, the wavelength (Wavelength) of the sea waves will increase, and there will be many small white hat waves on the sea surface. The wave height is roughly between 1-1.5 meters (3.5-5 feet).

6. Fresh Breeze or Force Five: Wind speed is between 17-21 knots. After the strong wind continues to blow for a period of time, the sea surface will set off medium waves with a longer wavelength (Wavelength), with a wave height between 2-2.5 meters (6-8 feet), and there will be white cap waves that are not very dense. Some of the white hat waves will appear and spray into the air due to the wind.

7. Strong Breeze or Force Six: The wind speed is between 22 and 27 knots. After strong winds continue to blow for a period of time, larger waves with a height of 3 to 4 meters (9.5 to 13 feet) will appear on the sea surface. White cap waves can be seen everywhere, and the waves (Crest) will burst out with spray (Spray) due to the wind. ) will have more white hat waves.

8. Near Gale or Force Seven: Wind speed is between 28 and 33 knots. After the strong wind continues to blow for a period of time, the waves will rise straight up, with the height of the waves roughly between 4 and 5.5 meters (13.5 and 19 feet). The white foam (Foam) produced after the waves break will begin to be blown away by the wind. Into a not very thick blanket and/or not very long strands.

9.Gale or Force Eight: Wind speed is between 34-40 knots. After the strong wind continues to blow for a period of time, the sea surface will set off medium-sized high waves with a long wavelength (Wavelength). The wave height is between 5.5 - 7.5 meters (18 - 25 feet). The waves will be blown into more fine shapes by the strong wind. Spindrift, the white foam broken from the waves will be distributed downwind in the form of blankets and/or wisps.

10. Strong Gale or Force Nine: The wind speed is between 41 and 47 knots. After strong winds continue to blow for a period of time, large waves with a wave height between 7-10 meters (23-32 feet) will appear on the sea surface. The waves will begin to roll violently, and a thicker blanket-like white foam will appear on the sea surface, mixed with long or long Short wisps of white foam and misty spindrift may reduce visibility.

11. Storm or Force Ten: wind speed between 48 and 55 knots. After the strong wind continues to blow for a period of time, the wave height will be between 9 - 12.5 meters (29 - 41 feet), and the wave will begin to appear like a mountain. A large number of blanket-like white foam will appear, making the sea surface appear paler, and the air will be dense with mist. Visibility will be greatly reduced. When a ship sails in strong winds, it will experience violent rolling and pounding from time to time.

12. Violent Storm or Force Eleven: wind speed between 56 and 63 knots. After the storm continues to blow for a period of time, the wave height will be between 11.5 - 16 meters (37 - 52 feet). The sea surface will not only have extremely rough waves, but also be covered with thick blanket-like white foam, and the surrounding environment will be dark. , visibility was extremely poor.

13. Typhoon or Hurricane: Winds above Force Eleven are called typhoons or hurricanes, with wind speeds of 64 knots or above.