Hot wire and hot film sensors are used for measurements of fluctuations in the wind. Such anemometers are in competition with both mechanical and sonic anemometers. At least some of the mechanical sensors are more stable in calibration, and less expensive. The high frequency resolution of the hot wire/hot film sensors, however, cannot be matched by any other anemometers. Also, they can be made small enough and fast enough to measure within the dissipation range. Hot wire sensors have been used in atmospheric turbulence measurements since 1936; there are review articles by Bradshaw (1963), Comte Bellot (1976), Corrsin (1963), and Sandborn (1972).