1911 Encyclopædia Britannica/Buys Ballot's Law

BUYS BALLOT’S LAW, in meteorology, the name given to a law which may be expressed as follows:—“Stand with your back to the wind; the low-pressure area will be on your left-hand.” This rule, the truth of which was first recognized by the American meteorologists J. H. Coffin and W. Ferrel, is a direct consequence of Ferrel’s Law (q.v.). 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. The law takes its name from C. H. D. Buys Ballot, a Dutch meteorologist, who published it in the Comptes rendus, November 1857.