Weather vanes point into the wind, showing which direction the air is coming from.

The longer version

A weather vane works because of its shape, not because of any external power. The small arrowhead at the front offers little resistance to the air, while the larger tail at the back catches much more, so the wind swings the assembly around until the tail sits downwind and the arrow faces into the flow.

It therefore shows where the air is coming from, which is the convention used in naming winds: a northerly wind blows from the north. Vanes are mounted on a low-friction pivot in open air, well away from buildings and trees that would otherwise distort the local flow.

Where this entry sits

Clouds, wind, rain, and storms shape daily life in ways that most people barely notice. This collection explains snow, lightning, rainbows, the turning seasons, temperature, the instruments forecasters rely on, and scraps of old weather lore. The full list sits on the Weather and Climate page, where every entry is listed in order.