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TRANSCRIPT
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THE OCEANS AND THE
ATMOSPHERE
Objectives
• Distinguish between the ocean’s three layers.
• Explain how the ocean affects the world’s climates.
• Explain why worldwide sea levels do not always stay
the same.
• Identify three common types of shorelines.
• Identify the four layers of Earth’s atmosphere.
• Relate the movement of air masses to climate zones.
The Oceans• Ocean basins
– No geologic record
of a time before
water
– The origin of water
on Earth is debated
• It is proposed that
water originated in
Earth’s interior
• Another proposal is
water arriving from
outer space through
meteorite impacts
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The Oceans
The Oceans
• Ocean basins
– Earth has 4 huge water basins
• The Pacific Ocean
• The Atlantic Ocean
• The Indian Ocean
• The Southern Ocean
– These bodies of water, together with some smaller ones,
cover 71% of Earth’s surface
The Oceans• The composition of seawater
– Salinity
• A measure of the salt content of a solution
• Salinity of seawater ranges between 3.3 and 3.7 percent
– Elements in seawater come from:
• Chemical weathering of rock
• Volcanic eruptions and black smokers
• Evaporation or surface water (increases salinity)
• Freezing of seawater (increases salinity)
– Maintains a constant salinity
• Salts added are balanced by salts removed by organisms and by
precipitation and deposition on sea floor.
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The Ocean• Layers in the ocean
– Three major layers in the oceans in which density differs
• Surface layer ( 2%,warmest)
• Thermocline (18%, just above the freezing point)
• Deep Zone (80%, temperature low and constant)
The Ocean
Shallow ocean
circulation
The Ocean
• Ocean currents (deeper than shallow circulation)
– “The Great Ocean Conveyor Belt” (thermohaline
circulation)
• North Atlantic Deep Water
• Antarctic Bottom water
• The Gulf Stream
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Thermal image showing northward movement
of Gulf Stream
The Ocean
• How oceans regulate climate
– Ocean moderates climate of coastal lands
– Conveyor belt re-distributes heat from the tropics to
the poles
• Elimination of conveyer belt (e.g., Gulf Stream) could cause
ice age. Glaciers would start to form in northern latitudes as
they did during the ice ages.
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Where the Ocean Meets Land
• Changes in sea level
– Global volume change
• Nearly imperceptible in
human lifetime,
• Account for great change in
position of shore line over
geologic time
– Tides
• Regular daily cycle of
raising and falling sea level
that results from the
gravitational action of the
Moon, Sun, and Earth
What Causes Tides?
http://www.youtube.com/watch?v=_J2AtORivSY
Bay of Fundy tides
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Waves in open waterWaves are generated by winds
blowing over the surface of the
ocean. Wave height depends on
wind velocity, duration, and fetch
(the distance over which the wind
blows).
Where the Ocean Meets Land
• Changes in sea level (continued)
– Waves
• Ocean waves receive
• energy from wind
• Surf
– The “broken”, turbulent water
found between a line of breakers
and the shore
• Rip currents-strong currents flowing out
to sea
• Wave refraction-bending of waves to
become more parallel to shoreline
http://www.youtube.com/watch?v=7nS_aR8XX_U
World’s biggest wave ever surfed
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Where Ocean Meets Land
• Changes in sea level continued
– Erosion and transport of sediment by waves
• Longshore current
– A current within the surf zone that flows parallel to the coast
• Beach drift
– The movement of particles along a beach as they are driven up and down the beach slope by wave action
Where Ocean Meets Land
Where Ocean Meets Land
• Three kinds of
shorelines and
coastal landforms
– 1. Rocky coasts
• Wave-cut cliff
– A coastal cliff cut
by wave action at
the base of a
rocky coast
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Formation of wave cut cliff
• Kinds of shorelines and coastal
landforms
– 2. Lowland beach and
Barrier Island• Beach: wave washed sand
along a shoreline
• Barrier Island: A long,
narrow, sandy island offshore
and parallel to a lowland coast
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Spit: body of sand
parallel to shore
deposited by longshore
currents. Connected to
shore.
Lagoon: body of
water between
barrier island or spit
and mainland.
Where Ocean Meets Land
• Kinds of shorelines and
coastal landforms
– 3. Reefs
• A hard structure on a
shallow ocean floor,
usually, but not always,
built by coral
• Polyps- tiny coral animals
that deposit calcium
carbonate
• Highly productive
ecosystems
Fringing reef
Barrier reef
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Atoll: can be produced by a
fringing reef around a volcano
that gradually subsides below
sea level. The reef grows
upward.
Earth’s Atmosphere
• Composition of Earth’s
atmosphere
– Air
• Gaseous envelope
surrounding Earth
• Comprised of 78%
nitrogen, 21% oxygen,
and trace amounts of other
gasses found in Earth’s
atmosphere
Earth’s Atmosphere
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Earth’s Atmosphere
Earth’s Atmosphere
• Troposhere
– Contains 80% of the mass of
the atmosphere
• Stratosphere
– Contains 19% of the
atmosphere’s total mass
– Ozone layer
• A zone in the stratosphere
where ozone is concentrated
• Mesosphere
• Thermosphere
Earth’s Atmosphere
• Composition of Earth’s
atmosphere
– Green house effect
• The process through which
long-wavelength (infrared) heat
energy is absorbed by gasses in
the atmosphere,
• This warms Earth’s surface
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Earth’s Atmosphere
Various layers in the
atmosphere absorb
harmfall short wave
(ultraviolet) radiation.
Depletion of the ozone layer could allow more
damaging radiation to enter the lower atmosphere.
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Circulation of the atmosphere transfers heat from near
the equator toward the poles.
Earth’s Atmosphere• Movement in the
atmosphere
– Convection currents
– Global circulation organizes
itself into three convection
cells
– Coriolis effect
• An effect due to Earth’s
rotation
• Causes a freely moving body
to veer from a straight path
Earth’s Atmosphere
• Movement in the
atmosphere continued
– Wind systems
• Intertropical convergence
zone
• Hadley cells
• Trade winds
• Polar cells
• Polar easterlies
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Earth’s Atmosphere
• How the atmosphere regulates climate
– Climate
• Average of weather patterns over a long period
– Köppen-Geiger climate system
• Defines climate zones on basis of temperature and
precipitation
Earth’s Atmosphere