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Waves, Tides, and Waves, Tides, and Currents Currents Science 6 Science 6

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Page 1: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Waves, Tides, and Waves, Tides, and CurrentsCurrents

Science 6Science 6

Page 2: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Where are the Oceans? Identify the Oceans

Tides

Currents

Waves

The Ocean Floor

Ocean Storms

Page 3: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms
Page 4: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

PREDICT: What percent of the earth is covered in water? What percent is land? Explain your prediction.

Page 5: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

PREDICT:What percent of the earth’s water is salt? What percent is fresh? Explain your prediction.

Page 6: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms
Page 7: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

WavesWaves

•A wave is a rhythmic A wave is a rhythmic movement that movement that carries energy carries energy through matter or spacethrough matter or space..

•All waves have the same main All waves have the same main partsparts..

Page 8: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

•Still-Water Line - The level of the ocean if it were flat without any waves.

Crest - The highest part of the wave above the still-water line.

Trough - The lowest part of the wave below the still-water line

•Wave Height - The vertical distance between the crest and the trough.

•Wavelength - The horizontal distance between each crest or each trough.

Page 9: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

•Wave Period - The time it takes for two successive waves to pass a particular point. For example, if you are standing on a pier and start a stopwatch as the crest of a wave passes and then stop the stopwatch as the crest of the next wave passes, you have measured the wave period.

Wave Frequency - The number of waves that pass a particular point in a given time period.

Fetch – The distance the wind blows over open water.

Amplitude - The amplitude is equal to one-half the wave height or the distance from either the crest or the trough to the still-water line.

Page 10: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

WavesWaves

• The highest part of a wave is the crest.The highest part of a wave is the crest.

• The lowest part of a wave is the trough.The lowest part of a wave is the trough.

Page 11: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Parts of Ocean WavesParts of Ocean Waves

Page 12: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

WavelengthWavelength• The distance from the crest of one wave to The distance from the crest of one wave to

the crest of the wave next to it is called the crest of the wave next to it is called wavelength.wavelength.

Page 13: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Wave HeightWave Height

• Wave height is the vertical distance from Wave height is the vertical distance from the trough to the crest.the trough to the crest.

Page 14: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms
Page 15: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

WavesWaves

• Most ocean waves are caused by Most ocean waves are caused by wind that blows across the surface of wind that blows across the surface of the waterthe water..

• Friction between the wind and water Friction between the wind and water transfers energy from the wind to the transfers energy from the wind to the water.water.

Page 17: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

WavesWaves

• The longer and harder the wind The longer and harder the wind blows and the greater the distance blows and the greater the distance over which it blows, the higher the over which it blows, the higher the waves become…..waves become…..

Page 18: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms
Page 19: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms
Page 20: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Wave MovementWave Movement

• The wave travels The wave travels forward…. forward….

• But the water But the water particles do notparticles do not!!

• The water particles The water particles move in a circular move in a circular pattern as they are pattern as they are temporarily temporarily displaced by the displaced by the energy of the wave.energy of the wave.

Page 21: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

© 2002 Brooks/Cole, a division of Thomson Learning, Inc.

Ocean WavesOcean Waves

Page 22: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Transfer of EnergyTransfer of Energy

• A wave is really a A wave is really a transfer of energy transfer of energy from one water from one water molecule to the nextmolecule to the next. .

• If all the water itself If all the water itself moved forward all the moved forward all the oceans would empty oceans would empty onto the shore!!!!!onto the shore!!!!!

Page 23: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Why Do Waves Break?Why Do Waves Break?• Water molecules do tend to travel forward Water molecules do tend to travel forward

as they break on shore.as they break on shore.

• Waves break when they approach shallow Waves break when they approach shallow waterwater..

Page 24: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

BreakersBreakers

• The bottom of the wave is slowed down The bottom of the wave is slowed down by friction with the ocean floor.by friction with the ocean floor.

• The top of the wave is still moving The top of the wave is still moving forward, traveling faster than the bottom.forward, traveling faster than the bottom.

• Its momentum causes it to move past the Its momentum causes it to move past the bottom part of the wave.bottom part of the wave.

• When this happens the wave topples over When this happens the wave topples over on itself, forming a breakeron itself, forming a breaker..

Page 25: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

© 2002 Brooks/Cole, a division of Thomson Learning, Inc.

Wind Waves Approaching Wind Waves Approaching ShoreShore

What happens when wind waves break against the shore?

Page 26: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Breaking WavesBreaking Waves• In general waves break when the depth of the In general waves break when the depth of the

water is a little greater than the height of the water is a little greater than the height of the wave.wave.

• Water depth 1.3 times the wave heightWater depth 1.3 times the wave height• A wave 30 cm high will break in 40 cm water.A wave 30 cm high will break in 40 cm water.

Page 28: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms
Page 29: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

• The gravitational forces of the moon and sun on the water causes the tides..

• The moon, being nearest, has the greatest effect even though the sun is the larger of the two.

• High tides are generated on the sides of the Earth nearest to and farthest from the moon

What causes tides?

Page 30: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

During new and full moon phases the moon, sun, and Earth are aligned causing a greater gravitational pull on the Earth.

This results in higher high tides and lower low tides.

Page 31: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Spring TidesSpring Tides• The Moon moves around Earth and Earth The Moon moves around Earth and Earth

moves around the Sun.moves around the Sun.• The Moon, Earth, and Sun line up twice a The Moon, Earth, and Sun line up twice a

month-when the moon is full and then month-when the moon is full and then when it is new.when it is new.

• The Moon and Sun pull together on The Moon and Sun pull together on EarthEarth’’s oceans.s oceans.

• The result is high tides that are very high The result is high tides that are very high and low tides that are very low; Spring and low tides that are very low; Spring TidesTides

• Spring refers to the Spring refers to the ““springing upspringing up”” of the of the water, not the spring season.water, not the spring season.

Page 32: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Neap TidesNeap Tides• When the Sun and Moon are at a 90 When the Sun and Moon are at a 90

degree angle with Earth, they no longer degree angle with Earth, they no longer pull in the same direction.pull in the same direction.

• The pull of the Sun works against the pull The pull of the Sun works against the pull of the Moon.of the Moon.

• High tides are not so high and low tides High tides are not so high and low tides are not so low; Neap Tidesare not so low; Neap Tides

• Occur twice each month, when the Moon is Occur twice each month, when the Moon is in its first quarter and its third quarter in its first quarter and its third quarter phases.phases.

Page 33: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Spring and Neap TidesSpring and Neap Tides

•http://home.hiwaay.net/~krcool/Astro/moon/moontides/

• http://www.enchantedlearning.com/http://www.enchantedlearning.com/subjects/astronomy/moon/subjects/astronomy/moon/Tides.shtmlTides.shtml

Page 34: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms
Page 35: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

What is a Current?

A current is a continuous flow of water in a given direction

A current is like a river in the ocean

Page 36: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Types of Ocean Currents

There are two types of currents in the ocean:

Surface Currents

Density Currents

Page 37: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Causes of Surface Currents

Three things cause surface currents:

1. Wind

2. Continents

3. Rotation of the Earth, also known as the Coriolis Effect

Page 38: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Heating of the Earth’s Surface

• The sun’s rays strike the Earth at different angles

• At the equator, the rays strike the Earth almost perpendicular to its surface, warming up a small area.

• At high latitudes, the curve of the Earth causes the rays to strike a larger surface area-So the same amount of heat is distributed over a larger area.

• The farther from the equator, the cooler the Earth

Page 39: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

What Causes the Wind?

• This difference in temperature between the equator and the poles causes our atmosphere and ocean to circulate.

• What does warm air do? • What does cooler air do?

• This exchange of warm air and cool air causes the winds that prevail over the Earth.

Page 40: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Fig. 16.14, p.407

Prevailing Winds

Page 41: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Surface Ocean Currents

•Surface currents are caused by the transfer of energy from winds.

•Surface currents occur in the top 100 – 300 m of water.– Example: Gulf Stream – 80km wide, 5km

velocity (at fastest)

•Gyre – circuit of currents around the periphery of an ocean basin (e.g. Gulf Stream is part of the North Atlantic Gyre)

Page 42: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

The water of the ocean surface moves in a regular pattern called surface ocean currents. The currents are named. In this map, warm currents are shown in red and cold currents are shown in blue.

Page 43: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Surface-Ocean Currents

• Most are part of the gyres that circulate in the ocean basins

• Gyres circulate clockwise in the northern hemisphere

• Gyres circulate counterclockwise in the southern hemisphere

• Why?

Page 44: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Fig. 16-12, p.384

Observe direction of circulation of gyres

Page 45: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

The Coriolis Effect

• The Coriolis Effect is caused by the Earth’s rotation.

• Because the Earth is spinning objects do not move above it in a straight line.

• Objects are deflected in a curved path.• This is what causes clouds in a hurricane

to swirl.• This is also why winds and currents

move in circular paths

Page 46: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Coriolis Effect

•Why don’t we notice the Coriolis Effect?

• Something has to move a very long way before the Coriolis effect is

noticeable - at least several hundred miles.

• For example, if you throw a football the path only curves a tiny bit due to the Coriolis effect - far too small for

you to ever notice.

Page 47: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Coriolis Effect AnimationCoriolis Effect Animation

• Click below for animationClick below for animation

• http://www.classzone.com/books/http://www.classzone.com/books/earth_science/terc/content/earth_science/terc/content/visualizations/es1904/visualizations/es1904/es1904page01.cfmes1904page01.cfm

• http://www.kidsgeo.com/geography-http://www.kidsgeo.com/geography-for-kids/0089-coriolis-effect.phpfor-kids/0089-coriolis-effect.php

Page 48: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Current: continuous flow of Current: continuous flow of water in a given directionwater in a given direction

Surface currents – wind-driven flow in the top Surface currents – wind-driven flow in the top 400m of seas 400m of seas

• Example: Gulf Stream – 80km wide by 650m deep, 5km Example: Gulf Stream – 80km wide by 650m deep, 5km velocity (at fastest)velocity (at fastest)

• Winds blow in particular directions due to Winds blow in particular directions due to differential heating of the earthdifferential heating of the earth’’s surfaces surface

• Gyre – circuit of currents around the Gyre – circuit of currents around the periphery of an ocean basin (e.g. Gulf periphery of an ocean basin (e.g. Gulf Stream is part of the North Atlantic Gyre)Stream is part of the North Atlantic Gyre)

• Westerlies and trade winds produce gyresWesterlies and trade winds produce gyres

Page 49: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Westerlies and trade winds Westerlies and trade winds produce gyresproduce gyres• Trade winds blow from east to west Trade winds blow from east to west

toward the equator. As they move over toward the equator. As they move over the oceans, they push surface currents the oceans, they push surface currents from east to west.from east to west.

• Westerly winds (westerlies) blow from Westerly winds (westerlies) blow from west to east, pushing surface currents west to east, pushing surface currents along with themalong with them..

• http://www.weatherwizkids.com/http://www.weatherwizkids.com/wind1.htmwind1.htm

• http://www.kidsgeo.com/geography-for-http://www.kidsgeo.com/geography-for-kids/0095-westerlies.phpkids/0095-westerlies.php

• http://www.kidsgeo.com/geography-for-http://www.kidsgeo.com/geography-for-kids/0094-trade-winds.phpkids/0094-trade-winds.php

Page 50: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms
Page 51: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Surface-Ocean CurrentsSurface-Ocean Currents

• Most are part of the gyres that Most are part of the gyres that circulate in the ocean basinscirculate in the ocean basins

• Gyres circulate Gyres circulate clockwise clockwise in the in the northern hemispherenorthern hemisphere

• Gyres circulate Gyres circulate counterclockwise counterclockwise in in the southern hemispherethe southern hemisphere

Page 52: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

                                       

                   

                                       

                   

                                       

                   

On your map, color the warm currents red and the cold currents blue. Label the 4 oceans.

Atlantic OceanPacific Ocean

Arctic Ocean

Indian Ocean

Page 53: Waves, Tides, and Currents Science 6. Where are the Oceans? Identify the Oceans Tides Currents Waves The Ocean Floor Ocean Storms

Neptune’s Web

Ocean Weather, Temperature, and Tides

Ocean Planet Exhibit in the Smithsonian Museum of Natural History

Secrets at Sea Game