The term for the distance over which wind blows uninterrupted is called the

   Fetch

Explanation:  Fetch is a measure that determines the distance, during which the wind blows without encountering any obstacles. Usually this refers to wind blowing over the surface of the sea, and fetch in that case is the distance in which the wind blows without meeting a reef, or before it reaches the coast. It means a clear distance above the sea surface without any obstacles is the fetch of the wind.

grav force prop 1/r squared 2r all squared is 4rsquared 1/4rsquared quartered