Final answer:
The deflection of moving fluids as a result of Earth's rotation is called the Coriolis force, which significantly affects large-scale phenomena like weather systems and ocean currents.
Step-by-step explanation:
The deflection of moving fluids such as air and water as the result of Earth's rotation is known as the Coriolis force. This inertial force causes the apparent deflection of moving objects when viewed in a rotating frame of reference, like that of the Earth. It is most observable on a large scale, like in the rotation of weather systems and ocean currents, where it has substantial effects. For example, in the Northern Hemisphere, the Coriolis force deflects moving fluids to the right, leading to the counterclockwise rotation of hurricanes, while in the Southern Hemisphere, it deflects to the left, causing a clockwise rotation.
The Earth's rotation is slow enough that it is nearly an inertial frame. To observe the effects of the Coriolis force, especially the fictitious forces and slight departures from Newton's laws, one must usually perform precise experiments or observe large-scale phenomena like weather patterns and ocean currents where the effects are easily noticeable.