Sailing Glossary - Term Sonic anemometer

An anemometer which measures wind speed by means of the properties of wind-borne sound waves. It operates on the principle that the propagation velocity of a sound wave in a moving medium is equal to the velocity of sound with respect to the medium plus the velocity of the medium. The sonic anemometer is an absolute instrument and has the advantages of a very short time-constant and an absence of moving mechanical parts.