Which instrument is primarily used to measure wind direction and speed?

The instrument primarily used to measure wind direction and speed is the anemometer. This device is specifically designed to assess wind characteristics, providing readings on both how fast the wind is blowing (speed) and in which direction it is coming from. An anemometer typically features rotating cups or blades that turn in response to the wind, with the rotation speed correlating to wind speed. Additionally, some anemometers are equipped with a wind vane component that determines wind direction, giving a comprehensive understanding of wind behavior in a given area.

In contrast, a barometer measures atmospheric pressure, a thermometer measures temperature, and a hydrometer assesses the specific gravity of liquids. Each of these instruments serves a distinct purpose and does not provide information about wind direction and speed, which is why they are not suitable for this specific measurement.