Buys Ballot's law

With the wind to one's back (the stick figure is facing out of the picture), a low-pressure center (L) will be to one's left, high pressure (H) to one's right (in the Northern Hemisphere)

In meteorology, Buys Ballot's law (Dutch pronunciation: [ˈbœyz bɑˈlɔt]) may be expressed as follows: In the Northern Hemisphere, if a person stands with their back to the wind, the atmospheric pressure is low to the left, high to the right.[1] This is because 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,[2] but the angle between the pressure gradient force and wind is not a right angle in low latitudes.

A version taught to US Naval Cadets in WW2 is: "In the Northern Hemisphere, if you turn your back to the wind, the low pressure center will be to your left and somewhat toward the front."[3]

  1. ^ Encyclopædia Britannica, Buys Ballot's Law, retrieved 2009-10-06
  2. ^ Bowditch, Nathaniel (2002). The American practical navigator : an epitome of navigation. United States. National Imagery and Mapping Agency. (2002 bicentennial ed.). Bethesda, Md.: The Agency. p. 513. ISBN 0-16-051125-9. OCLC 50648886.
  3. ^ Aerology for Pilots, McGraw-Hill, (published under the supervision of the Training Division, Bureau of Aeronautics, US Navy) 1943, p. 43