Chapter 16. Ocean current-mass of ocean water that flows from one place to another Surface currents...
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Transcript of Chapter 16. Ocean current-mass of ocean water that flows from one place to another Surface currents...
The Dynamic OceanChapter 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
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
WavesWhere do waves
come from?The energy from
strong windsParts of a wave
A –crestB –troughC –wavelengthD –amplitude
Wave Period and SpeedWave period
the time it takes for a complete wave to pass a given point
Wave speedhow fast the waves
are travelingWavelength ÷
period
Factors that Affect the height, length and period of a wave
Speed of the windDuration
how long the wind will blow
Fetchthe length of water
surface over which the wind blows in a constant direction
BreakersSpilling breakers
over-steepened waves that are unstable and the top spills over. Occur on flat beaches.
Plunging breakersHawaii (large
splash)
Types of WavesWind wavesTsunamis
tidal waves formed by movements on a fault line
Internal wavesOccurs within the
water and not on the surface. “dead water”
TidesWhat are they and how do they work?
TidesWhat are Tides?
changes in elevation of the ocean surface
What causes Tides?Gravitational forces of the moon and sun
Tidal RangeVertical 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.
Spring Tides
Spring TidesOccur during the new and full moons
All gravitational forces are added together
Extreme high and low tides
High tidal range
Neap TidesNeap Tides
During the 1st and 3rd quarters of the Moon
Gravitational forces are offset
Tidal range is the smallest value
TidesTides occur 50 minutes later due to …Rotation pattern of earth and moon.
This is known as a lunar day
Tidal PatternsDiurnal (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
Mixed2 high and 2 low tides
each day. Each high and low tides are different from each other. Occurs on the west coast.
Coast, Beaches and ShoresBeach
accumulation of sediment (sand and gravel) that occupies a portion of the shore. (moving)
Coastwhere 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.
Forces that act on a shoreWave Impact
changes the shapeAbrasion
most intenseWave refraction
sediment transportation
Longshore transportworks with
refraction
Longshore CurrentsLongshore 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
Rip CurrentsRip currents
water current formed when water moves to the sea through a break in an offshore bar.
Erosion FeaturesSea Arches
form when two caves are eroded and unite.
Spitelongated ridge of
sand that projects from the land into the mouth of a bay and hooks.
Erosion FeaturesTombolo
ridge of sand that connects an island to the mainland or another island.
Baymouth Barsandbar that has
completely crossed a bay, sealing it.
Barrier islandNarrow sandbars
parallel to, but separated from the mainland.
Protective StructuresGroin/Jetty
structures that are at right angles to the beach to trap sand.
Breakwater/Seawallstructures built parallel
to the shoreline to protect the coast from powerful breakers.
Bulkheadstructure separating
land and water areas –reduces erosion.
Beach NourishmentAddition of large
quantities of sand to the beach system