The Coriolis effect is an apparent deflection of moving objects when the motion is depicted relative to a rotating reference frame.
deflection: action/process to turn aside/change direction from straight path
relative to: in relation, comparison, or proportion to thing (or measured from a reference frame)
[3]
In a reference frame with clockwise rotation, the deflection is to the left of the object's motion; in one with counterclockwise rotation, the deflection is to the right. Though recognized previously by others, the mathematical expression for the Coriolis force appeared in an 1835 paper by French scientist Gaspér-Gustave de Coriolis, in connection to the water wheels theory.
The fundamental cause of the Coriolis effect is Earth's rotation. Due to its rotation on its axis from west to east (near the equator) move faster than those near the poles. If an object or fluid moves northward/southward away from the equator, it retains its initial eastward momentum. As it travels to higher latitudes where the Earth moves slower beneath it, the object appears to curve eastward relative to the surface. Conversely, an object moving from a pole toward the equator lags behind the faster-moving land beneath it, curving westward relative to the ground.
conversely: in opposite/reversed manner; introduce statement contrasting with
In physical geography and meteorology, the Coriolis effect plays a critical role in shaping global weather patterns and atmospheric circulation. It prevents air from flowing directly from high-pressure to low-pressure areas, instead causing winds to curve around pressure centers. This deflection drives the rotation of large storm systems: cyclonic weather systems rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Similarly, ocean currents are deflected by the Coriolis force, producing large rotating gyres across major ocean basins.
The Coriolis effect must also be accounted for in ballistics, aviation, and spaceflight. Long-range projectiles, such as naval artillery shells and missiles, undergo measurable lateral displacement during flight if the rotation of the Earth is not factored into targeting equations. Aircraft flying long distances must continuously make minor navigational adjustments to maintain a straight ground track.
Since the Earth does a full rotation a day, the Coriolis force exerted on small regular objects is weak. Consequently, usual myths suggesting household water drains clockwise or counterclockwise depending on the hemisphere are false; the rotation direction in a domestic sink/toilet is determined by the basin's shape and initial water currents rather than planetary rotation.
The Coriolis force is an apparent/inertial force acting upon an object in motion within a rotating reference frame.
The reference frame provides a centrifugal force that pushes things outward or into its internal frames, like gravity does to anything on Earth, causing its path to deflect to the right/left while the Coriolis force deflects it sideway, but only if the object is moving across the rotating frame.
[4] Fig. 1
[4] Suppose an astronaut, in space, in a spinning disk-shaped hollow space ship, where his feet are stuck to the ground like on Earth due to the centrifugal effect exerted onto his body. If they released a ball, it's dropped down onto the ground or outward due from the disk due to the centrifugal force, similar as gravity (Fig. 1).
[4] Fig. 2
[4] If the ball is thrown upward, the it'll travel in a straight line away from them til it touches the edge of the wheel (Fig. 2).
However, in reality, the ball would also deviant a bit as it fell.
If it's thrown higher, it's thrown further while deviating to the ground (Fig. 3).
The force that causes the ball to deviate is the Coriolis force
[4] Fig. 3
While spinning, each point inside the wheel has a circular force that rotates alongside the wheel (Fig. 4).
By throwing the ball up, it approaches the rotation axis and should move slower to follow the wheel, but as it conserved its initial motion, it moves faster than the wheel and go by it and fall to the other side (Fig. 5).
[4] Fig. 4
[4] Fig. 5
If the wheel were larger, the Coriolis force would be negligible. This works similarly in carousels and on Earth.