Wind as a predominantly horizontal motion of air compensates the difference between spheres of different atmospheric pressure. It is a directed quantity (vector) therefore the measurement of direction and speed is necessary for its complete description.

The wind direction is defined as that direction from which the wind blows. To give details about it one uses a direction scale called wind rose in which the north direction is defined as zero and counting is done clockwise. Main wind directions are North (360°), East (90°), South (180°) and West (270°).
The wind speed is a measurement of the distance the moving air particles cover per time unit. So it may be given in m/s or in km/h or mph respectively. In international use also knot (1 kn= 1 sm/h)

The measurement of the horizontal wind speed and wind direction is taken by an anemometer 10m above even and obstacle free ground.

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