The wind vane is one of the oldest meteorological instruments (known since classical Greece). Installed at 10 metres height (WMO standard), its pointer shows where the wind comes from: pointing north means a north wind. It is paired with an anemometer for speed.
Modern vanes in automatic stations use potentiometers or optical encoders and report direction in degrees (0–360°). Wind direction is vectorially averaged over 2–10 minutes to filter turbulent fluctuations.