which weather instrument could be used to determine the direction that wind is blowing
Measurement techniques. A variety of instruments can be used to measure wind direction, such as the windsock and wind vane. Both of these instruments work by moving to minimize air resistance. The way a weather vane is pointed by prevailing winds indicates the direction from which the wind is blowing. The larger opening of a windsock faces the direction that the wind is blowing from; its tail, with the smaller opening, points in the same direction as the wind is blowing. Modern instruments used to measure wind speed and direction are called anemometers and wind vanes, respectively.