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Ch 16

Ch 16. The Dynamic Ocean. Surface Circulation. Surface Currents movements of water that flow horizontally near the surface develop from friction between the ocean and the wind. Surface Circulation. Gyres huge circular-moving current systems that dominate the surfaces of the oceans.

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Ch 16

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  1. Ch 16 The Dynamic Ocean

  2. Surface Circulation • Surface Currents • movements of water that flow horizontally near the surface • develop from friction between the ocean and the wind

  3. Surface Circulation • Gyres • huge circular-moving current systems that dominate the surfaces of the oceans. • Coriolis effect • deflection of currents away from their original course as a result of Earth’s rotation

  4. Ocean Currents and Climate • Currents from low-latitude regions moving into higher latitudes transfer heat from warmer to cooler areas • Upwelling • rise of cold water from deeper layers to replace warmer surface water • brings greater concentrations of dissolved nutrients to the surface

  5. Deep Ocean Circulation • Densitycurrents • Vertical currents of ocean water that result from density differences among water masses • Increases in seawater density can be caused by a decrease in temperature or an increase in salinity

  6. Conveyor Belt Model • Ocean circulation is similar to a conveyor belt that travels from the Atlantic Ocean, through the Indian and Pacific Oceans, and back again.

  7. Waves • Most ocean waves obtain their energy and motion from the wind. • wave height - vertical distance between the trough and crest. • Wavelength - horizontal distance between two successive crests or two successive troughs. • wave period - time it takes one full wave to pass a fixed position. • Fetch - distance that the wind has traveled across open water.

  8. Tides • Daily changes in the elevation of the ocean surface • Result from the gravitational attraction exerted upon Earth by the moon

  9. Tides • Tidal range - difference in height between successive high and low tides • Spring tides - have the greatest tidal range due to the alignment of the Earth–moon–sun system • Neap tides - have the lowest tidal range, occurring near the times of the first-quarter and third-quarter phases of the moon.

  10. Forces Acting On The Shoreline • Waves along the shoreline are constantly eroding, transporting, and depositing sediment. • Wave Impact • Abrasion - the sawing and grinding action of rock fragments in the water • Wave Refraction - the bending of waves

  11. Forces Acting On the Shoreline • Wave Refraction • Because of refraction, wave energy is concentrated against the sides and ends of headlands that project into the water, whereas wave action is weakened in bays.

  12. Forces Acting On The Shoreline • Longshore Current - a near-shore current that flows parallel to the shore • Turbulence allows longshore currents to easily move fine suspended sand and to roll larger sand and gravel particles along the bottom.

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