Meaning of Buys-Ballot's law

Buys'-Bal•lot's' law"

Pronunciation: (bīs'bu-lots'), [key]
— Meteorol. Meteorol.
  1. the law stating that if one stands with one's back to the wind, in the Northern Hemisphere the atmospheric pressure will be lower on one's left and in the Southern Hemisphere it will be lower on one's right: descriptive of the relationship of horizontal winds to atmospheric pressure.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.