Buys Ballot, Christoph Heinrich Diedrich

Buys Ballot, Christoph Heinrich Diedrich (krĭs`tôf hīn`rĭkh dēd`rĭkh bois` bälō`), 1817–90, Dutch meteorologist. Director of the Dutch Royal Meteorological Institute after 1854, he strove to organize and standardize a system for representing meteorological findings and formulated (1857) Buys Ballot's law. This states that, in the Northern Hemisphere, if one stands with his back to the wind, the area of low pressure is to his left. In the Southern Hemisphere the reverse is true. The explanation lies in the deflection, caused by the earth's rotation, in the movement of air from areas of high pressure to areas of lower pressure. A related law had been deduced earlier by the U.S. meteorologist William Ferrel.