Dutch meteorologist and chemist Christoph Hendrik Diederik Buys Ballot (1817–1890) was a pioneer in meteorology, especially when it came to explaining how air flows in large weather systems. The law that bears his name refers to the fact that when you stand with your back to the wind, the air pressure will be lower on your left than on your right in the Northern Hemisphere, and the opposite is true if you are standing in the Southern Hemisphere. This phenomenon—which actually only proves to be true during well-organized weather systems—was also discovered by American climatologist William Ferrel (1817–1891). Ferrel actually formulated this theory a few months before Buys Ballot. The Dutchman graciously acknowledged that the credit deserved to go to Ferrel, but the “law” had already been denoted Buys Ballot’s Law, and the name stuck.