Buys-Ballot's law, in meteorology, is the name given to a law which may be expressed as follows: In the Northern Hemisphere, stand with your back to the wind; the low pressure area will be on your left. In other words, wind travels counterclockwise around low pressure zones in the Northern Hemisphere. It is approximately true in the higher latitudes of the Northern Hemisphere, and is reversed in the Southern Hemisphere, but the angle between barometric gradient and wind is not a right angle in low latitudes. See Coriolis effect#Flow around a low-pressure area.

This rule, which was first deduced by the American meteorologists J.H. Coffin and William Ferrel, is a direct consequence of Ferrel's law. The law takes its name from C.H.D. Buys-Ballot, a Dutch meteorologist, who published it in the Comptes Rendus, November 1857. While William Ferrel theorized this first, Buys-Ballot was the first to provide an empirical validation.

Some of this article's text is from the public domain 1911 Encyclopædia Britannica.

External links

• M. Buys-Ballot, "Note sur le rapport de l'intensite et de la direction du vent avec les ecarts simultanes du barometre", Comptes Rendus, Vol. 45 (1857), pp. 765–768.

Midlatitude weather | Atmospheric dynamics | Eponymous laws

Buys-Ballotovo pravidlo | Barisches Windgesetz | Leyes de Buys-Ballot | Wet van Buys Ballot | Reguła baryczna