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Earth Science Chapter 10 Oceans

Terms in this set (69)

Ocean Currents
are masses of water flowing from one place to another.
they are developed by friction between the wind and the ocean
Gyres
a collection/system of ocean currents that follow circular pathways
How many gyres are there in the world?
5:
North Atlantic Gyre
South Atlantic Gyre
North Pacific Gyre
South Pacific Gyre
Indian Ocean Gyre
The northern hemisphere gyres are
clockwise
the southern hemisphere gyres are
counter-clockwise
The clockwise and counter-clockwise motions of the northern and southern hemispheres are due to
the coriolis effect
Coriolis Effect
a deflective force of Earth's rotation on all free-moving objects, including the atmosphere and oceans. Deflection is to the right in the northern hemisphere and to the left in the the southern hemisphere.
poleward-moving currents are
warm
equator-moving currents are
cold
the West Wind Drift is the only current that
completely encircles Earth
Cold currents exert their greatest influence in the
tropics or during the summer months in the middle latitudes
How do surface-ocean currents have an important effect on climate?
-gains in solar energy=to the losses to space of heat radiated from surface
-the transfer of heat by winds and ocean currents equalizes these latitudinal energy imbalances
-ocean water movements account for about 1/4 of this total heat transport, and winds account for the remaining 3/4
Upwelling is
the rising of cold water from deeper layers to replace warmer surface water, is a common wind-induced vertical movement
One type of upwelling is most characteristic along the west coasts of continents most notably along California, western South America, and West Africa
Coastal upwelling
When does coastal upwelling occur
the wind blows toward the equator and parallel to the coast
Deep-ocean circualtion is referred to as
thermohaline circulation: Temperature & salinity
when the density of the seawater increases
the temperature decreases
when the salinity of the seawater increases
the density increases
Anatomy of a wave
An ocean wave is energy traveling along the water-air interface
an interface is
a common boundary where different parts of a system interact
Waves form via
friction between the wind and water
the distance to the wave base
is half of the wavelength
the distance to the surf zone
is 1/20 of the wavelength
tops of waves
are crests
crests are separated by
troughs
the vertical distance between trough and crest is
wave height
the horizontal distance between successive crests
is the wavelength
the time it takes for a full wave to pass by a stationary object is called
period
to calculate wave velocity
you divide wavelength/wave period (distance/time)
factors that affect wave size, period, etc are
1. wind speed
2. length of time wind blows
3. fetch (total distance in which wind blows)
Sand movement on the beach is controlled by
waves
the beach is a river
of sand
two things that cause sand movement on the beach
1. wave refraction
2. longshore transport
Wave refraction is
the bending of waves to make wave land parallel to shore geometry
longshore transport deals with
1. beach drift (zig zag)
2.long-shore current (in surf zone)
effect of wave refraction
refraction concentrates energy on headland areas (stick out) and decreases energy in the protected bays
Shoreline features have two parts
Erosional and Depositional
Erosional shoreline features are
-wave-cut cliffs
-wave-cut platform
-marine terrace
-sea arch
-sea stack
Depositional shoreline features are
-spit
-baymouth bar
-tombolo
-barrier islands
abrasion is
the sawing and grinding action of the water armed with rock fragments; is more intense than the surf zone
wave-cut cliffs
originate in the cutting action of the surf against the base of coastal land
wave-cut platforms
are a relatively flat, benchlike surface
marine terrace
if a wave-cut platform is uplifted above sea level by tectonic forces
sea arch
when two caves on opposite sides of a headland unite
sea stack
when the arch falls in leaving an isolated remnant on the wave-cut platform
spit
elongated ridge of sand that projects from the land into the mouth of an adjacent bay, often end in the water hooks landward in response to dominant direction of longshore current
baymouth bar
is applied to a sandbar that completely crosses a bay, sealing it off from the open ocean. tends to form across bays where currents are weak, allowing spit to extend to other side
tombolo
a ridge of sand that connects an island to the mainland or to another island, forms in same manner as a spit
Barrier island
low ridges of sand parallel the coast at distances from 3 to 30 kilometers offshore
structures built to protect a coast from erosion or to prevent the movement of sand along a beach are known as
hard stabilization
Groins
is a barrier built at a right angle to the beach to trap sand that is moving parallel to the shore
breakwater
is designed to protect boats from the force of large breaking waves by creating a quiet water zone near the shore
seawall
is designed to armor the coast and defend property from the force of breaking waves
what are the two non-structural responses
1. beach nourishment
2. relocation
Beach nourishment
bring sand from elsewhere or use a vacuum ship to replenish the sand on the beaches (ex: Outer Banks)
Tides
rhythmic changes in the ocean's surface elevation. Caused by gravitational forces of the moon and sun
Monthly Tidal Cycle
the Moon orbits Earth 1 time every 29 days
Spring Tides
moon, sun, and earth are aligned
Neep Tides
moon is perpendicular to earth and sun line
Tidal Patterns are influenced by 3 things
1. shape of the coastline
2. configuration of ocean basin
3. depth of water
What are the 3 tidal patterns
1. diurnal
2. semidiurnal
3. mixed
Diurnal
single high and low tide each day
ex: Gulf of Mexico
Semidiurnal
2 high and low tides of roughly equal magnitudes
ex: Atlantic coast of North America
Mixed
2 high and low tides per day, but of unequal magnitudes
ex: pacific coast of north america
Coastal Classifications
coasts are classified based on changes that have occurred with respect to sea level.
what are the 2 types of coastal classifications
1. Emergent
2. Submergent
Emergent
develop because area experiences uplift or as a result of drop of sea level
Some examples include regions once buried beneath ice sheets
ex: California
Submergent
created when sea level rises or land adjacent to sea subsides
Estuaries are
drowned river mouths (types of submergent coasts)
ex: Chesapeake and Delaware estuaries (Bays)
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