A joint initiative of the Department of Fisheries and Woodside Energy • http://marinewaters.fish.wa.gov.au The Coriolis Effect V2-05 – Apr 2012/1.1 • PAGE 1

The Coriolis Effect

1. OVERVIEW

Students will understand the concept of the Coriolis Effect by attempting to draw a straight line on a rotating disc and apply this principle to understanding ocean gyres.

2. LInks TO CuRRICuLumCURRICULUM FRAMEWORK (WA)

Learning Area OutcomeScience Investigating Communicating Scientifically Science in Daily Life Earth and beyond

Society and Environment Natural and Social Systems

English Viewing

Mathematics Working Mathematically Space

AUSTRALIAN CURRICULUM

Strand Sub-strandSCIENCEScience Understanding Earth and Space Sciences Physical SciencesScience Inquiry Skills Questioning and Predicting

MATHEMATICSMeasurement and Geometry Shape Location and Transformation Problem solving

3. ObjECTIVEsStudents will:

•Demonstrate an understanding of how motion appears to be affected by the rotation of a sphere.

4. TEACHER bACkgROund InFORmATIOnThe earth rotates on its axis, completing a full cycle every 24 hours. This means people on Earth are in fact moving at several hundred kilometres an hour, but we do not feel this rotation. This is because we are attached to the earth’s surface and are travelling with the rotation.

However, there is an influence over large distances for moving objects, such as an aeroplane flying to its destination or a missile aimed at a target.

The earth’s rotation causes moving objects, including water and air, to be deflected to the left in the Southern Hemisphere and to the right in the Northern Hemisphere. This force is called the Coriolis Effect.

There are some common misconceptions about the Coriolis Effect. For instance, the direction of water draining from a sink in the Southern and Northern Hemisphere has no link to the Coriolis Effect. It’s mainly due to the configuration of the plumbing!

Topics

Ocean Currents

Phase of Learning

7–10

site (location)

Classroom

Activities & duration

1. Deflected – 45 minutes

2. Down the Drain – 45 minutes

3. Ocean Gyres – 30 minutes

materials

• World globe

• Torch or lamp

• Circular disc template (North and South Pole Polar projections)

• Glue

• Cardboard box or ice cream container with top

• Drawing pin or push pin

• Scissors

• Pencil

Vocabulary

Axis (Earth’s)

Coriolis Effect

Eddy

Equator

Force

Gyre

Northern Hemisphere

Ocean Current

Southern Hemisphere

student Worksheets

1. Deflected

2. Ocean Gyres

PROCEssEs – Physical & biological Processes

A joint initiative of the Department of Fisheries and Woodside Energy • http://marinewaters.fish.wa.gov.au The Coriolis Effect V2-05 – Apr 2012/1.1 • PAGE 2

Equator

Axis

Figure 1 Moving objects are deflected to the left in the Southern Hemisphere and right in the Northern Hemisphere due to the Coriolis Effect.

Teacher Tip

The Coriolis Effect is named after French mathematician Gustave Gaspard de Coriolis (1792 –1843).

The result of the Coriolis Effect on our atmosphere and oceans is giant circulating wind eddies (cyclones and anticyclones) and ocean gyres (Figure 2).

There are five giant ocean gyres: North Atlantic, South Atlantic, North Pacific, South Pacific and South Indian.

Strong ocean currents on the eastern coast of continents such as the Gulf Stream (USA), Kuroshio Current (Japan), East Australian Current (Australia) and Brazil Current (South America) are a result of the rotational pattern of gyres.

Ocean gyres help circulate the water in the world’s oceans by moving warmer tropical waters from the equator southwards and cooler nutrient-rich water northwards. Prevailing westerlies and trade winds strongly influence the flow of ocean gyres.

Figure 2 Location and direction of global ocean gyres and major surface ocean currents.

Vocabulary

Axis (Earth’s): the imaginary line going through the north and south poles around which the earth spins.

Coriolis Effect: deflection of objects or substances moving along the surface of the earth, rightward in the Northern Hemisphere and leftward in the Southern Hemisphere.

Eddy: a water (or air) current moving against the direction of the main current, especially in a circular motion, i.e. whirlpool.

Equator: an imaginary line around the earth equidistant from the poles, dividing the earth into two equal symmetrical parts, i.e. Northern and Southern Hemispheres.

Force: any influence that produces a change in the velocity of an object.

Gyre: a circular system of ocean currents rotating clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

Northern Hemisphere: the half of the earth between the North Pole and the equator.

Ocean current: continuous steady movement of ocean water in a prevailing direction and defined area.

Southern Hemisphere: the half of the earth between the South Pole and the equator.

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A joint initiative of the Department of Fisheries and Woodside Energy • http://marinewaters.fish.wa.gov.au The Coriolis Effect V2-05 – Apr 2012/1.1 • PAGE 3

5. TEACHER PREPARATIOnUse the world globe to begin a discussion about the earth’s rotation. Reinforce students’ understanding of the concept of clockwise and counterclockwise direction.

Access the following video from BBC Four http://www.youtube.com/watch?v=Wda7azMvabE which offers a light-hearted approach to explaining the Coriolis Effect and could be shown to students after Activity 1: Deflected.

Students will work in pairs to complete Activity 1. A template has been provided and should be printed on single sided paper. Collect enough small cardboard boxes or a substitute to place a drawing pin into.

6. PROCEduRE

ACTIVITy 1: deflected

Working in pairs, students will demonstrate the concept of the Coriolis Effect by attempting to draw a straight line on a rotating disc.

steps

1. Use a world globe (or other sphere such as a large ball) to discuss how the earth rotates on its axis.

2. Locate the Equator, Northern and Southern Hemispheres, and North and South Poles.

3. Direct a light source to simulate day and night on a slowly spinning world globe. Why don’t we feel anything as the Earth moves?

4. Have the materials available for each pair.

5. Direct students to read and follow directions on Student Worksheet 1: Deflected and reinforce safety when using scissors. This activity requires Appendix 1: Southern Hemisphere and Northern Hemisphere Template to complete the worksheet.

6. Monitor and check students’ answers.

References

Australian Bureau of Meteorology, Forecasting the weather: Monitoring the weather, http://www.bom.gov.au/info/ftweather/page_14.shtml

ABC Science 2010, Which way do cyclones spin? Australian Broadcasting Corporation, http://www.abc.net.au/science/articles/2010/03/24/ 2853824.htm [10 October 2010].

NASA: Ocean Motion, Wind driven surface current: Gyres background, http://oceanmotion.org/html/background/wind-driven-surface.htm

NOAA Ocean Education Service, Currents, http://oceanservice.noaa.gov/education/tutorial_currents/welcome.html

student Worksheet

1. Deflected

Appendix 1: Southern Hemisphere and Northern Hemisphere Template

A joint initiative of the Department of Fisheries and Woodside Energy • http://marinewaters.fish.wa.gov.au The Coriolis Effect V2-05 – Apr 2012/1.1 • PAGE 4

ACTIVITy 2: down the drain

Students will debunk a common misconception that water draining from a sink in the different Hemispheres will swirl in a certain direction due to the Coriolis Effect.

steps

1. Ask students if they have noticed the direction water drains from a sink or bath when the plug is pulled. They may believe that the above misconception is a truth.

2. Instruct the students that they will be conducting an experiment to test whether water exiting a sink will travel in a counterclockwise direction (deflected to left) as per Activity 1. Develop some hypotheses.

3. Locate several sinks in the school where water can be filled and a plug pulled. The sink need not be filled completely (promote water efficiency). One-third full is probably enough to cover the plug and generate water movement.

Teacher Tip

Alternatively, ask students to perform the experiment at home and report their findings in class the following morning.

4. Collate and discuss results back in the classroom.

5. View the story Coriolis from ABC TV Catalyst program 30 March 2006 http://www.abc.net.au/catalyst/stories/s1604444.htm

6. Reinforce the concept that the Coriolis Effect applies to moving objects over large distances.

ACTIVITy 3: Ocean gyres

Students will locate on a map the world’s five giant ocean gyres.

steps

1. Using the world globe, lead a discussion about how the investigation in Activity 1 and 2 revealed how ocean currents would be deflected.

2. Help students locate ocean gyres using the figure provided in the lesson plan or set a research task.

3. Locate the five main ocean gyres.

4. Using Student Worksheet 2: Ocean Gyres, locate and draw the five main ocean gyres. Make sure to include arrows showing direction of flow and name of the gyre.

Related Resources

Coriolis: Catalyst 2006, television program, Australian Broadcasting Corporation, 30 March. http://www.abc.net.au/catalyst/stories/s1604444.htm. [10 July 2010]

BBC Four 2009, What’s the Coriolis Effect? – Winds, video, 23 April, http://www.youtube.com/watch?v=Wda7azMvabE. [10 July 2010].

student Worksheet

2. Ocean Gyres

A joint initiative of the Department of Fisheries and Woodside Energy • http://marinewaters.fish.wa.gov.au The Coriolis Effect V2-05 – Apr 2012/1.1 • PAGE 5

sTudEnT WORksHEET 1: deflected

deflectedIn this activity you will discover the strange effects of the Coriolis Effect.

Instructions:

1. You have been provided with a template of the earth viewed from the South Pole and another viewed from the North Pole. To complete your Earth, stick them together using glue, making sure that the two pages line up accurately.

2. Cut out the earth.

3. Indicate the direction of the earth’s rotation by drawing an arrow in a clockwise direction in the Southern Hemisphere and an arrow in a counterclockwise direction in the Northern Hemisphere.

4. Using a cardboard box or other materials provided by your teacher, place your Earth on top and push through a drawing pin into the South Pole.

5. Find a partner to rotate the earth in slow and steady pace.

6. Using a pencil, try to draw a straight line from the South Pole to Perth, while your partner starts to rotate the earth in a clockwise direction.

7. Where did the line end up?

__________________________________________________________________________________

8. Which direction was the line deflected?

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9. Flip the Earth to the Northern Hemisphere.

10. Try drawing a straight line from the North Pole to Tokyo, Japan, while your partner starts to rotate the earth in a counterclockwise direction.

11. Where did the line end up?

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12. Which direction was the line deflected?

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13. Based on your findings, describe how your two lines behaved when trying to draw a straight line.

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14. Write your own definition of the Coriolis Effect.

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Name: _______________________ Date: __________

A joint initiative of the Department of Fisheries and Woodside Energy • http://marinewaters.fish.wa.gov.au The Coriolis Effect V2-05 – Apr 2012/1.1 • PAGE 6

APPEndIx 1: Hemisphere Templates

southern Hemisphere Template

A joint initiative of the Department of Fisheries and Woodside Energy • http://marinewaters.fish.wa.gov.au The Coriolis Effect V2-05 – Apr 2012/1.1 • PAGE 7

APPEndIx 1: Hemisphere Templates continued...

northern Hemisphere Template

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Name: _______________________ Date: __________

sTudEnT WORksHEET 2: Ocean gyres

Ocean gyresLabel and draw the direction of the five giant ocean gyres.

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suggEsTEd AnsWERs: Ocean gyres

Ocean gyres

NORTHPACIFIC

NORTHATLANTIC

SOUTHATLANTIC

SOUTHPACIFIC

SOUTHINDIAN