This lesson introduces the Coriolis force, explains why it appears in rotating frames, and traces how scientists came to understand it. These ideas matter because Earth’s rotation influences large-scale motion in the atmosphere and oceans.
A reference frame is a viewpoint or coordinate system used to describe motion. An inertial frame is not accelerating or rotating. Newton’s laws take their simplest form in such a frame. Earth’s surface, however, rotates, so an observer fixed to Earth uses a rotating frame.
All flashcards
Why is the Coriolis force called a pseudo-force?
It is an apparent force used to describe motion from a rotating frame, not a separate physical interaction.
What determines the strength of the Coriolis force?
The object's mass, the frame's rotation rate, and the object's velocity relative to that frame.
What is geostrophic flow?
Large-scale flow in which pressure-gradient and Coriolis forces nearly balance, making motion approximately parallel to isobars.
What is the Eötvös effect?
A small vertical contribution to Coriolis acceleration, such as the upward acceleration of eastward-moving objects near the equator.
What is a Coriolis flow meter used to measure?
Fluid mass flow rate and density, using changes in the vibration of a fluid-carrying tube.
Quiz questions
An object moves parallel to the rotation axis of a rotating frame. What is its Coriolis force?Answer: Zero, because its velocity is parallel to the frame's angular velocity.
When does the Euler force arise in a rotating reference frame?Answer: When the frame's angular velocity changes with time.
In low-Rossby-number flow, what force balance produces approximately geostrophic motion?Answer: A near balance between pressure-gradient and Coriolis forces.
In which direction does air circulate around a low-pressure system in the Northern Hemisphere?Answer: Anticlockwise
For an air parcel moving under the Coriolis force alone, how does inertial-circle radius depend on speed and Coriolis parameter?Answer: It equals speed divided by the Coriolis parameter.
Based on the Wikipedia article Coriolis force, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.