In hurricane reports, people in high rise buildings above the 10th floor are advised to go to lower floors to avoid the higher wind speeds occurring at higher elevations. Why are wind speeds higher as the altitude increases?
Dean Clark, Glencoe
Friction with the ground and ground-based objects is the answer. Air moving across objects loses energy to those objects and slows down accordingly. This is true in all situations, not just in hurricanes. Winds at the ground are lower than a foot higher up, stronger at a few feet above the ground, and higher still as one goes above that. In most instances, wind speeds increase up to the top of the planetary boundary (friction) layer generally located about 2,000 ft. above ground level. Above this level, frictional drag becomes negligible.