I know the basic answer, that the movement of air sets things vibrating which makes noise, but I don't know the specifics. For example, if the wind is blowing hard, you can often hear the wind howling at a certain pitch. This seems to be dependent on velocity because the harder the wind blows, the higher the pitch is. How does this happen? Are sounds made by the wind primarily due to the air itself vibrating or to solid objects vibrating when the air blows against them? Also, is there an easy way to predict what the frequency of the howl will be based on how fast the wind is blowing?