Apparent wind in knots and degrees. Note that a number of additional factors come into play when converting the measurements from the masthead anemometer into the true wind if a high degree of accuracy is required, including the following: In the presence of a current, the true wind is considered to be that measured on the craft drifting with the water over the bottom, and wind with respect to the sea bed as the "ground" or "geographical wind". The apparent wind on board (a boat) is often quoted as a speed measured by a masthead transducer containing an anemometer and wind vane
Wind profile power law of wind speed can provide different power densities for the same average wind speed. Wind profile power law The wind profile power law is a relationship between the wind speeds at one height, and those at another. The wind profile power law relationship is : where formula_2 is the wind speed (in metres per second) at height formula_3 (in metres), and formula_4 is the known wind speed at a reference height formula_5. The exponent (formula_6) is an empirically derived coefficient that varies dependent upon the stability of the atmosphere. For neutral stability conditions, formula_6 is approximately 1/7, or 0.143. In