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The Dynamic Ocean

The Dynamic Ocean. Chapter 16. Ocean current -mass of ocean water that flows from one place to another Surface currents movements of water that flow horizontally in the upper part of the ocean’s surface Upwelling rise of cold water from deeper layers to replace warmer surface water

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The Dynamic Ocean

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  1. The Dynamic Ocean Chapter 16

  2. Ocean current-mass of ocean water that flows from one place to another • Surface currents • movements of water that flow horizontally in the upper part of the ocean’s surface • Upwelling • rise of cold water from deeper layers to replace warmer surface water • brings greater concentrations of dissolved nutrients, such as nitrates and phosphates, to the ocean surface • Density currents • vertical currents of ocean water that result from density differences among water masses

  3. Waves • Where do waves come from? • The energy from strong winds • Parts of a wave • A –crest • B –trough • C –wavelength • D –amplitude

  4. Wave Period and Speed • Wave period • the time it takes for a complete wave to pass a given point • Wave speed • how fast the waves are traveling • Wavelength ÷ period

  5. Factors that Affect the height, length and period of a wave • Speed of the wind • Duration • how long the wind will blow • Fetch • the length of water surface over which the wind blows in a constant direction

  6. Breakers • Spilling breakers • over-steepened waves that are unstable and the top spills over. Occur on flat beaches. • Plunging breakers • Hawaii (large splash)

  7. Types of Waves • Wind waves • Tsunamis • tidal waves formed by movements on a fault line • Internal waves • Occurs within the water and not on the surface. “dead water”

  8. Tides What are they and how do they work?

  9. Tides • What are Tides? • changes in elevation of the ocean surface • What causes Tides? • Gravitational forces of the moon and sun

  10. Tidal Range • Vertical distance between the high and low tides. • Vary from place to place and week to week. • Many factors (shape of the coastline, configuration of ocean basins, and water depth) influence tidal ranges.

  11. Spring Tides • Spring Tides • Occur during the new and full moons • All gravitational forces are added together • Extreme high and low tides • High tidal range

  12. Neap Tides • Neap Tides • During the 1st and 3rd quarters of the Moon • Gravitational forces are offset • Tidal range is the smallest value

  13. Tides • Tides occur 50 minutes later due to … • Rotation pattern of earth and moon. • This is known as a lunar day

  14. Tidal Patterns • Diurnal (daily) • one high and one low tide each lunar day. Occurs at Pensacola, Fl. And the Gulf coast. • Semidiurnal (semi-daily) • 2 high and 2 low tides: each high and low tides are similar to the preceding high and low. Occurs in the Atlantic coast • Mixed • 2 high and 2 low tides each day. Each high and low tides are different from each other. Occurs on the west coast.

  15. Coast, Beaches and Shores • Beach • accumulation of sediment (sand and gravel) that occupies a portion of the shore. (moving) • Coast • where the land meets the sea. • “lands edge that boarders the sea” • Shore • part of the coast in which the outer limits of wave action influences the land.

  16. Forces that act on a shore • Wave Impact • changes the shape • Abrasion • most intense • Wave refraction • sediment transportation • Longshoretransport • works with refraction

  17. Longshore Currents • Longshore current • caused by waves which approach the shore at an angle –move sand grains along the beach (responsible for the beach erosion on the barrier islands) • Littoral drift • the movement of sand along the beach because of longshore currents

  18. Rip Currents • Rip currents • water current formed when water moves to the sea through a break in an offshore bar.

  19. Erosion Features • Sea Arches • form when two caves are eroded and unite. • Spit • elongated ridge of sand that projects from the land into the mouth of a bay and hooks.

  20. Erosion Features • Tombolo • ridge of sand that connects an island to the mainland or another island. • BaymouthBar • sandbar that has completely crossed a bay, sealing it. • Barrier island • Narrow sandbars parallel to, but separated from the mainland.

  21. Protective Structures • Groin/Jetty • structures that are at right angles to the beach to trap sand. • Breakwater/Seawall • structures built parallel to the shoreline to protect the coast from powerful breakers. • Bulkhead • structure separating land and water areas –reduces erosion.

  22. Beach Nourishment • Addition of large quantities of sand to the beach system

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