A typhoon is a mature tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere. This region is referred to as the Northwestern Pacific Basin, and is the most active tropical cyclone basin on Earth, accounting for almost one-third of the world's annual tropical cyclones. Anyone who has ever looked at an image of a hurricane knows it spins. Part of this is due to the center of low pressure — the “eye” — at the center of the storm. But it also has to do with physics. In fact, tropical cyclones — the general name for the storms called typhoons, hurricanes or cyclones in different parts of the world — always spin counterclockwise in the Northern Hemisphere, and spin in the opposite direction in the Southern Hemisphere.