Buys-Ballot's law

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Facing the wind, high-pressure area (H) is on your left-hand side on the north hemisphere

In meteorology, Buys-Ballot's law 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.

[edit] 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.

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.