In physics, the Coriolis force is an inertial force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motion of the object. In one with anticlockwise rotation, the force acts to the right. Deflection of an object due to the Coriolis force is called the Coriolis effect. Though recognized previously by others, the mathematical expression for the Coriolis force appeared in an 1835 paper by French scientist Gaspard-Gustave de Coriolis, in connection with the theory of water wheels. Early in the 20th century, the term Coriolis force began to be used in connection with meteorology.
Image from Cursus seu Mundus Mathematicus (1674) of C.F.M. Dechales, showing how a cannonball should deflect to the right of its target on a rotating Earth, because the rightward motion of the ball is faster than that of the tower.
Image from Cursus seu Mundus Mathematicus (1674) of C.F.M. Dechales, showing how a ball should fall from a tower on a rotating Earth. The ball is released from F. The top of the tower moves faster than its base, so while the ball falls, the base of the tower moves to I, but the ball, which has the eastward speed of the tower's top, outruns the tower's base and lands further to the east at L.
A carousel is rotating counter-clockwise. Left panel: a ball is tossed by a thrower at 12:00 o'clock and travels in a straight line to the center of the carousel. While it travels, the thrower circles in a counter-clockwise direction. Right panel: The ball's motion as seen by the thrower, who now remains at 12:00 o'clock, because there is no rotation from their viewpoint.
Due to the Coriolis force, low-pressure systems in the Northern hemisphere, like Typhoon Nanmadol (left), rotate counterclockwise, and in the Southern hemisphere, low-pressure systems like Cyclone Darian (right) rotate clockwise.
Gaspard-Gustave de Coriolis
Gaspard-Gustave de Coriolis was a French mathematician, mechanical engineer and scientist. He is best known for his work on the supplementary forces that are detected in a rotating frame of reference, leading to the Coriolis effect. He was the first to apply the term travail for the transfer of energy by a force acting through a distance, and he prefixed the factor ½ to Leibniz's concept of vis viva, thus specifying today's kinetic energy.
Gaspard-Gustave de Coriolis
Title page of an 1829 copy of "Du Calcul de L'Effet Des Machines"
Introductory page of an 1829 copy of "Du Calcul de L'Effet Des Machines"
First page of an 1829 copy of "Du Calcul de L'Effet Des Machines"
