What is Buys Ballot’s law?

In 1857, Buys Ballot formulated a law identifying the relationship between wind and pressure distribution. The law states that

Face the true wind and the low-pressure area will be on your right hand side in the northern hemisphere, left in the southern hemisphere.

 CAUTION!!! Buys Ballot’s Law should not be applied

  • Near the equator: This is because the Coriolis Force is negligible at or within few degrees of the equator and therefore winds blow directly across the isobars from HP to LP areas.
  • In the vicinity of land: The wind experienced may not be the free unobstructed wind. It may be wind deflected by the land.