ocean’s motion
DESCRIPTION
Ocean’s Motion. Waves, Tides and Currents. Ocean Waves. What is a Wave?. . A wave is described as the periodic up-and-down movement of water. They are caused by the wind blowing over the surface of the water. Tsunami’s are large waves caused by earthquakes underwater. . Wave Features. - PowerPoint PPT PresentationTRANSCRIPT
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Ocean’s Motion
Waves, Tides and Currents
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Ocean Waves
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What is a Wave?
.• A wave is described as the periodic
up-and-down movement of water.• They are caused by the wind blowing
over the surface of the water.
Tsunami’s are large waves caused by earthquakes underwater.
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Wave Features
Wave period = the time it takes 2 consecutive wave crests to pass a given point. A wave’s speed is calculated by dividing wavelength over wave period.
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Water Movement in a Wave
• Like the bottle in the diagram, water molecules do not travel horizontally through the water with the wave.Let’s try it!
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What impacts Wave Size?• 3 factors
determine the size of the wave– Speed of the
wind– Length of time
wind blows– Fetch –
distance wind can blow across open water
• Large waves produced by strong, steady winds blowing across a long fetch.
• When wind blows crest of wave off, whitecaps are formed
Whitecaps
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How do waves impact the shoreline?
• Long shore drift is the movement of sand along the beach due to wave actions.
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What are Ocean Currents?• Ocean
currents are moving streams of water within the ocean.
• There are two types of currents: surface currents and deep currents.
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What causes surface currents?
• Currents that move on or near the surface of the ocean
• 3 factors that control surface currents – air currents, Earth’s rotation, and location of continents
• All surface currents are affected by winds
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What do you notice about the direction of the currents?
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Why do currents spin?
• The Earth spins counter-clockwise.
• This spinning body deflects winds and currents depending on what side the equator they are on.
• This is called the corialis effect
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The Great Conveyor Belt moves heat around the globe with the help of warm surface currents and colder deep currents.
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How do deep current form?
• Deep currents are caused by changes in temperature and salinity.
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What causes deep currents to move if the wind doesn’t have an
effect on it? • Water density moves the water. • Cold water is more dense and it
sinks and moves.• Warm water is less dense and it
rises.• Note: surface currents travel
much faster than deep ocean currents.
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How are deep water currents helpful?
• Deep currents help move nutrients around the ocean.
• Upwelling's are cold deep currents that move to the surface bring with them nutrients from the ocean floor.
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What are tides?• Periodic rise and
fall of water level in the oceans
• High tide – water level is at its highest
• Low tide – water level is at its lowest
Tides at the Bay of Fundy
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What is the Cause of Tides?
• The gravitational pull of the moon on Earth and Earth’s waters is the major cause
• Sun also causes tides but they are smaller because the sun is so much farther from Earth than the moon
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Formation of Tides
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There are two types of tides
Spring Tides
Occur when the Earth, Sun and Moon are in a line.
• Causes extra high and low tides.
Neap Tides• Occur when the Sun
and the Moon are at right angles to one another.
• Causes the smallest tidal movements. There is little difference between low and high tides.
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Types of Tides• Tidal range = difference in
levels of ocean water at high tide & low tide
• Spring tides = Occurs during the new moon & full moon; results in higher high tides and lower low tides.
• Neap tides = occurs during 1st & 3rd quarter moons; daily tidal range is small.