Wind direction is measured by using a device called a wind vane. This instrument, which is also referred to as a weather vane, is typically mounted at high places, such as rooftops.
In meteorological terms, wind direction pertains to the direction where the wind originates. Traditionally, wind vanes are designed with an arrow pointer in front and fins in the rear. The instrument works by aligning the pointer to where the wind is blowing. For instance, a southerly wind causes the arrow to point southward.
Wind direction can also be determined by using a windsock, which is commonly used in airports. It is also useful when approximating wind velocities.