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? Parts of a wave
The energy from strong winds
Parts of a wave
A –crest
B –trough
C –wavelength
D –amplitude

4. Wave Period and Speed Wave period Wave speed
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 Plunging 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 Internal waves
tidal waves formed by movements on a fault line
Internal waves
Occurs within the water and not on the surface. “dead water”

8. What are they and how do they work?
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 Occur during the new and full moons
All gravitational forces are added together
Extreme high and low tides
High tidal range

12. 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) Semidiurnal (semi-daily) Mixed
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
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
Longshore transport
works with refraction

17. Longshore Currents Longshore current Littoral drift
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 Spit
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 Baymouth Bar Barrier island
ridge of sand that connects an island to the mainland or another island.
Baymouth Bar
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