The Coriolis effect is the apparent deflection of a moving object due to the rotation of the Earth. Winds, moving water, ships, and aircraft are among those things most noticeably affected. A moving object, water current, or airstream appears to be deflected to its right in the Northern Hemisphere and to its left in the Southern Hemisphere.
The deflection is sometimes explained as being caused by a hypothetical force, called the Coriolis force, which acts in a direction perpendicular to the direction of the motion of the object. The effect is named after the French mathematician G. G. de Coriolis, who published an explanation of it in 1835.