Wind and Altitude: The Boating Encylopedia

Wind and Altitude: Information from Answers.com: "The speed of the wind rises with altitude, where it is less affected by the friction of the sea. This difference is discernible even over a relatively short distance equal to the height of a yacht’s mast.It follows, then, that if the true wind speed is higher aloft, the apparent wind direction up there is different from the apparent wind down below."