Indicates wind direction

Answer:

Wind vane or weather vane  

windsock

Explanation:

Your question should be what indicates wind direction?

Firstly, wind is the movement or motion of air in the atmosphere.  Wind can be measured in various way depending on the information you are after. One may want to measure the speed or the direction.

Wind direction is where the wind blows from,  that is the direction where it comes from. For example the wind that blows from the north is known as northerly wind . Wind direction can be measured in degree. Various techniques and instruments can be use to indicate or measure wind direction . A rather crude method is ardently listening to the sound ofwind . One can also use a wet finger to know the direction of wind.

A sophisticated  method to indicate wind direction is the windvane or windsock. The wind vane has a horizontal pole resting on a vertical pole that allows for easy movement of the horizontal pole.  The horizontal pole has a flattened end on the edge. The prevailing wind changes the direction of the horizontal pole thereby indicating direction of the wind.

The wind sock act almost the same manner as the wind vane. Only that a light fabric is attached to the vertical pole . when wind blows the light fabric get filled with air and stretched horizontally , giving you the direction where the wind blows.  The picture above is a wind vane and a wind sock.