Ocean Waves, Tides and Currents

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Ocean Waves, Tides and Currents
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Waves

• A Wave is a rhythmic movement that carries energy
  through matter or space.
• In oceans, waves move through seawater

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Waves

• Caused by
• Wind
• Earthquakes
• Gravitational force of the Moon and Sun.

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Parts of a Wave

• Crest highest point of a wave
• Trough lowest point of a wave
• Wave Height vertical distance between the crest
  and the trough
• Wavelength horizontal distance between two
  crests or two troughs

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Wavelength
Crest
Wave Height
Still Water
Trough
Wave Parts
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Wave Movement

• When a wave passes through the ocean, individual
  water molecules move up and down but they do not
  move forward or backward.

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Wave Movement

• When a wave breaks against the shore, the crest
  outruns the trough and the crest collapses.
• Called a breaker.
• In this case, water does move forward and
  backward.

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Waves Caused by Wind

• When wind blows across a body of water, friction
  causes the water to move along with the wind.
• Wave Height depends on
• Wind speed
• Distance over which the wind blows
• Length of time the wind blows

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Tides

• The rise and fall in sea level is called a tide.
• Caused by a giant wave.
• One low-tide/high-tide cycle takes about 12 hrs
  and 25 min.
• Tidal range is the difference in ocean level
  between high-tide and low-tide

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What is the Tidal Range?

• HT 30 ft, LT 20 ft
• HT 20 ft, LT 12 ft
• HT 50 ft, LT 20 ft

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Gravitational Effect of the Moon

• Two big bulges of water form on the Earth
• one directly under the moon
• another on the exact opposite side
• As the Earth spins, the bulges follow the moon.

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Gravitational Effect of the Sun

• Spring Tides
• Earth, Moon, and Sun are lined up
• High Tides are higher and Low Tides are lower
  than normal

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Gravitational Effect of the Sun

• Neap Tides
• Earth, Moon, and Sun form right angles
• High Tides are lower and Low Tides are higher
  than normal

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Ocean Currents

• Currentstream like movement of water in the
  ocean
• Two Types
• Surface Currents
• Deep Currents

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Surface Currents

• Found at or near the surface of the ocean
• 3 factors affect surface currents
• Global Winds
• Coriolis Effect
• Continental Deflections

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Surface Currents

• Global Winds
• Winds blow across the Earths surface in
  different directions
• Winds blow either
• East to West
• West to East

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Surface Currents

• Continental Deflections
• When currents meet continents, the currents
  deflect
• Change Direction

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Surface Currents

• Coriolis Effect
• Rotation of the earth effects winds and currents
• Wind and water move along curved paths.

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Deep Currents

• Deep waters
• Controlled by water density
• Density is affected by salinity and temperature

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The End