Why should the wind at the weather automatic station be calibrated to the north?

Because facing north, there is no projection and no reflection. The shadow of obstacles around the automatic weather station should not be projected on the light receiving surface of the sunshine and radiation observation instrument, and there is no object with strong sunlight reflection nearby. The wind measurement of meteorological automatic stations should be selected in places that can represent the weather and climate characteristics of most surrounding areas, and try to avoid the influence of small areas and local environment. At the same time, it should be chosen on the windward side with the strongest local wind, not in valleys, depressions, steep slopes and cliffs.