Objects that indicate the direction of the wind are known as weather vanes. Not all, however, are man made.
Flag trees, for example, are living weather vanes. They show the direction of the prevailing wind in a particular location. On mountain ridges, where trees are constantly exposed to strong winds, the windward facing branches of a tree are often stunted or killed. On the leeward side, the trunk shelters the branches. This allows them to grow to normal size. As a result, the tree is sculpted to the shape of the wind and resembles a flag waving in a breeze.
These deformed trees are common features in the windswept sub-alpine landscape, but are not limited to that terrain. Flag trees can also be seen in the tropics, where the strong, sustained trade winds contort trees in a similar fashion near the equator.
Photo Credit: jmu.edu