The Coriolis Effect
Lesson notes
Overview
On a rotating planet, moving air and water curve — right in the north, left in the south. This topic is rated intermediate and is number 19 of 98 in Earth & Space. Builds on the basics with relationships, methods and trade-offs.
What you are seeing
The panel above shows a model of an Earth or space system that you can adjust. The animation is drawn live from the model, so everything you see responds to the sliders. Press Space to pause, use Restart to replay from the start, and change the speed to slow down quick events.
In depth
Because the Earth rotates, moving air and water appear to curve when viewed from the surface: to the right in the northern hemisphere and to the left in the southern. The effect arises because the surface moves faster at the equator than near the poles, and the apparent acceleration is a = −2Ω × v. It is zero at the equator and strongest at the poles. It makes cyclones spin anticlockwise in the north and clockwise in the south, and shapes the wind and ocean currents.
Reading the relationship
The expression "a_c = −2Ω × v" is a compact summary of the idea. It uses the symbols a_c, Ω, v; name what each one stands for before you start. Then use the sliders to see how changing one quantity changes the others.
A guided exploration
1. Run the animation once with the default settings and describe in words what happens. 2. Change one slider at a time and note which quantity responds most. 3. Push each slider to its extreme and decide whether the result still makes sense.
Try this
Predict the outcome first, then test extreme slider values to find where the pattern changes or breaks.
Common pitfalls
Earth and space systems work on very different scales of time and distance. Check which scale a number refers to before comparing it with another.
How it connects
It builds on “Enhanced Greenhouse Warming”, the topic before it in Earth & Space. Once you are comfortable, continue with “Global Wind Circulation”.
Why it matters
Earth and space science helps us understand our planet, its climate and the wider universe.
Where you might use it
- Revising “The Coriolis Effect” before a class, exam or certification
- Forecasting weather and understanding climate records and their uncertainty
- Planning for earthquakes, floods and other natural hazards in cities
- Interpreting satellite images, space missions and the age of rocks and stars
Frequently asked questions
What is The Coriolis Effect?
On a rotating planet, moving air and water curve — right in the north, left in the south. It is an intermediate topic in Earth & Space.
How do I use the The Coriolis Effect simulation?
The panel at the top shows a model of an Earth or space system that you can adjust. Move the sliders one at a time, then press Space to pause the animation and look closer.
What does the formula mean?
The expression a_c = −2Ω × v packs the idea into symbols. Name each symbol first, then change one quantity with the sliders and see which others respond.
Who is this topic for?
Builds on the basics with relationships, methods and trade-offs. If the quiz feels hard, reread the lesson notes and try the previous topic first.
What should I learn before this?
Start with “Enhanced Greenhouse Warming”, the previous topic in Earth & Space. Each topic in a subject builds on the ones before it.
How do I track my progress?
Press “Mark as learned” on this page. Progress is stored only in this browser and is never sent anywhere. The Browse page can show topics you have learned or still need to learn.
Quick quiz
More in Earth & Space
See all →Global Wind Circulation
Hadley, Ferrel and polar cells move heat from the equator, bent by the Coriolis effect.
Ocean Currents and the Conveyor Belt
Wind and density differences drive a global circulation of heat through the oceans.
El Niño and La Niña
Shifts in Pacific trade winds and sea surface temperature alter weather worldwide.