The Beaufort Wind Force Scale
The Beaufort Wind Force Scale was created in 1805 by Sir Francis Beaufort, an Irish-born Royal Navy Officer. He developed a wind speed empirical model that could be understood by everyone.
The wind table features intensity levels and its corresponding general weather description, wind speed, wave height, sea and land conditions, sea state photo, and associated warning flag.
The Beaufort Wind Force Scale is the best way of assessing, with your eyes only, the wind speed in a determined spot. By observing the behavior of elements in the ocean and land, it is possible to measure the average wind force.
Although it is not a 100 percent accurate tool - the best anemometers in the world do it better - the Beaufort Wind Force Scale lets you know if, for example, you will be able to windsurf or sail away.
The scale goes from "Calm" (Level 0) to "Hurricane Force" (Level 12). The last stage of the Beaufort Wind Force Scale indicates you're experiencing more than 64 knots of wind.
From the Level 6 on, there are warning flags associated with each step up in wind speed category. It's safe to say that you probably won't be windsurfing from Level 10 on when storm warnings are raised.
The Beaufort Wind Force Scale is paramount for amateur and recreational surfers, but it should also be taken into consideration by all sailors in general. If you're riding in extreme wind conditions, the probabilities of damaging your sail are very high, and you will be putting your life at risk too.
By the way, do you know what wind is and how it is formed?
Check out the Beaufort Wind Force Scale: