Buys Ballot's law
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Buys Ballot's law(baɪs bəˈlɒts; bɔɪs)
(Physical Geography) a law stating that if an observer stands with his back to the wind in the N hemisphere, atmospheric pressure is lower on his left, and vice versa in the S hemisphere
[named after C. H. D. Buys Ballot (1817–90), Dutch meteorologist]