Harvepino/ShutterstockPicture a hurricane: A huge wind storm traveling in a circle around the eye. Weirdly enough, every hurricane you see spins counterclockwise—and even during the worst hurricane season in a while, you’ll never see one in the Southern Hemisphere.
It all comes down to the Earth’s rotation. No matter where in the world you are, it takes the planet 24 hours to rotate once—but certain areas are moving faster than others.
Think about it: If you’re standing right by the North Pole, you’d only end up traveling six feet or so in a day, so you’d be going about 0.00005 miles per hour. But on the equator, you’d need to make it all 25,000 or so miles around the Earth—about 1,040 miles per hour, according to the NOAA and NASA.
Those different speeds create something called the Coriolis effect, which gives storms a curved path. To put it in perspective, picture yourself standing on the equator, directly south of New York City. At the equator, you’d be standing on the fastest part of the world. Once you let go of the ball, it will keep up that fast west-to-east speed, even when it gets to the slower parts of the world. The ball’s path would curve, so it would end up landing a bit east of New York instead of right on it.
Tropical storms go through that same effect. As a tropical storm starts to brew, the winds start moving toward an area of low pressure near the surface of the water. The storms are big enough for the Coriolis factor to have an effect. In the northern hemisphere, air moving north curves east, while the air moving south curves west—a counterclockwise direction.
In the south, the winds do just the opposite, and the clockwise storms are called typhoons instead of hurricanes. (Learn the difference between more nature words you always confuse.)
Winds get pushed away from the equator, so you’ll actually never find a hurricane or typhoon within less than seven degrees of the equator, says meteorologist Chris Landsea, a science and operations officer at the National Hurricane Center. “Right on the equator, the winds and low pressure areas don’t feel the force of the Coriolis itself,” Landsea tells CNBC. “So one of the safest places from hurricanes in the tropics is right on the equator, because hurricanes never form there or track there.” If you aren’t lucky enough to be on the equator for hurricane season, learn how a water bottle could save your life during a hurricane.
Looking for more tropical storm trivia? Find out where hurricanes get their names from.