Apparent wind that measures wind speed in knots and wind direction in degrees relative to the heading of the boat. Modern instrumentation can calculate the true wind velocity when the apparent wind and boat speed and direction are input. In sailboat racing, and especially in speed sailing, apparent wind is a vital factor, when determining the points of sail a sailboat can effectively travel in. A vessel traveling at increasing speed relative to the "prevailing wind" will encounter the wind driving the sail at a decreasing angle and increasing velocity. Eventually, the increased drag and diminished degree of efficiency of a sail
Wind power in Thailand kW capacity at Hua Sai District in Nakhon Si Thammarat Province, and later in 2009, another of 1.5 MW capacity. Also in 2009, two wind turbines of 1.25 MW capacity each were installed by EGAT at the upper reservoir of Lam Takhong Cholapawattana power plant, a hydroelectric power plant in Sikhio District, Nakhon Ratchasima Province, becoming Thailand’s first large electricity-generating wind power plant. Thailand has relatively low average wind speeds with most areas being of class 1-1.4 wind speed, or about 2.8–4 m/s measured at 10 m. This is because Thailand is near the equator which has generally low wind