In meterological observations the mean wind is usually an average taken over ten minutes preceding the time of observation. A gust is a fluctuation above the mean typically lasting from a few seconds to a few minutes. Windflow is always turbulent due to the roughness of the Earth's surface. Gustiness is much increased by the presence of buildings, trees and rocky country, but at the same time the mean wind is decreased by friction. For this reason winds over the sea are usually less gusty then over land.
Wind direction is measured in degrees from true north.
The knot unit has its origins in naval history. Wind speeds are often given on the Beaufort scale which was originally devised for ships at sea. In forecasts for ships or aircraft, wind speed is usually quoted in knots.