Hurricanes and tropical storms that hit North America or any place in the northern hemisphere spin counterclockwise. All cyclones and tropical storms in the southern hemisphere spin clockwise. The direction of a hurricane’s spin is caused by a phenomenon called the Coriolis effect.

Hurricanes are the most violent storms on Earth. They form near the equator over warm ocean waters. Actually, the term hurricane is used only for the large storms that form over the Atlantic Ocean or eastern Pacific Ocean.

Hurricanes usually form in the Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and the Pacific Ocean. Hurricanes are most common in the Pacific Ocean, but the Western Pacific is the most active.

Hurricanes form when warm moist air over water begins to rise. The rising air is replaced by cooler air. This process continues to grow large clouds and thunderstorms. These thunderstorms continue to grow and begin to rotate thanks to earth’s Coriolis Effect.

At least 31 tropical cyclones have affected Western Africa and its surrounding islands since records began in 1851. The majority of the storms affect West Africa and Cape Verde islands during the months of August and September which are the active months of a typical Atlantic hurricane season.

Thanks to the Coriolis Effect’s impact on air and water, the movement happens in a curved direction; the north goes to the right and the south goes to the left. This is why hurricanes rotate counterclockwise in the northern hemisphere and cyclones in the southern hemisphere rotate clockwise.

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If the Earth did not rotate on its axis, the atmosphere would only circulate between the poles and the equator in a simple back-and-forth pattern.

Remarkably, hurricanes spin counter-clockwise in the Northern Hemisphere and clockwise in the Southern hemisphere. This differential spinning is due to Earth’s rotation. It is this pushing that causes hurricanes in the North to rotate counter-clockwise and those in the South, clockwise.

Because of the rotation of the Earth, the Coriolis effect means that hurricanes and other giant storm systems swirl counter-clockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere. In theory, the draining water in a toilet bowl (or a bathtub, or any vessel) should do the same.

The Coriolis force is simply too weak to affect such small bodies of water. The Coriolis force is caused by the earth’s rotation. It is responsible for air being pulled to the right (counterclockwise) in the Northern Hemisphere and to the left (clockwise) in the Southern Hemisphere.