You can use a variety of tools to determine the direction of the wind. In a pinch, you can simply put your finger in the air to feel the wind’s direction, but if you need a more accurate reading, try a wind sock or a pinwheel. These and other instruments are useful as aids in determining weather patterns, or simply measuring the current conditions.
Wind socks are very basic devices that measure wind direction and provide a rough idea of the wind's intensity. A wind sock is a tubular piece of fabric or thin, flexible fabric attached to a pole. When there is no wind, the fabric hangs vertically from the attached pole. When wind begins to blow through the wind sock, it fills the windsock and causes the sides to expand away from each other. This results in the windsock's rounded, cylindrical appearance and also causes the windsock to raise up to a horizontal position. Either the pole or the harness attached to the windsock can rotate when the wind changes direction, so the direction of the windsock will indicate the direction of the wind.
A weather vane works similarly to a wind sock. Instead of a tubular sock, the weather vane is made by placing a horizontal pole at the top of a vertical pole. The poles are joined together so that the horizontal pole can move independently of the structure's base. The horizontal pole has a flattened, vertical end that reacts to wind. This flattened end may be any broad, flat shape, such as the traditional rooster shape. When wind blows on the broad side of this end, it pushes it and causes the pole to rotate. When the pole has rotated to a position parallel to the wind's direction, the flattened end is also parallel, and air moves by the flattened end on either side of it without having any further effect the pole's position.
A pinwheel is a windmill-style turbine that spins perpendicularly to the wind affecting it. Like wind socks and weather vanes, a pinwheel can be attached to a rotating base. This allows the pinwheel to change direction with the wind, and it will spin facing into the oncoming wind.
An anenometer is any device that measures wind direction and intensity. It may be simple, such as the devices described above, or it may be a complex, computer-aided machine that measures and records wind patterns over time. More advanced anenometer machines are used to aid in professional weather reporting and air traffic control. They are also used to monitor the ideal conditions for spacecraft launches, and as surveying tools when prospecting for wind-generated power stations.