Glossary
Fetch
The unobstructed distance that wind travels across a water surface. A longer fetch lets wind sweep away more moist air and build waves, generally increasing wind-driven evaporation over large open water bodies.
Fetch is why wind speed and surface size interact: a large reservoir with a long fetch loses more to wind than a small, sheltered pond at the same wind speed. Reducing fetch — for example with windbreaks — is one way to cut wind-driven loss.