Buys Ballot , Christoph Hendrik Diederik

(1817–1890) Dutch meteorologist

Buys Ballot was the son of a minister from Kloetinge in the Netherlands. He was educated at the University of Utrecht, obtaining his PhD in 1844, and became professor of mathematics in 1847 and professor of physics in 1867. He did much to organize the observation and collection of meteorological data in the Netherlands and founded, in 1854, the Netherlands Meteorological Institute.

He is best remembered for the law on wind direction he formulated in 1857. This states that an observer facing the wind in the northern hemisphere has the lower pressure on his right and the higher pressure on his left; in the southern hemisphere this is reversed. Its justification is clearer if stated in the equivalent form: in the northern hemisphere winds circulate counterclockwise around low-pressure areas and clockwise around high-pressure ones.