Download Ocean Waves, Tides, and Shorelines CHECK YOUR ANSWER

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CHAPTER 24:
THE OCEANS, ATMOSPHERE, AND
CLIMATIC EFFECTS
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley
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Final Exam
Sect. S, TUESDAY DEC, 4
7:15 - 9:15 P.M.
I.C Room 421
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley
This lecture will help you
understand:
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Earth’s Atmosphere and Oceans
Components of Earth’s Oceans
Ocean Waves, Tides, and Shorelines
Components of Earth’s Atmosphere
Solar Energy
Driving Forces of Air Motion
Global Circulation Patterns
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Earth’s Atmosphere and Oceans
Earth is 71% covered by water. Water’s high
specific heat capacity accounts for moderate
temperatures in coastal lands.
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Earth’s Atmosphere and Oceans
Earth’s early atmosphere appeared
before the Sun was fully formed.
• Hydrogen
• Helium
Sun’s formation swept away Earth’s
original atmosphere and a new
atmosphere formed.
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Earth’s Atmosphere and Oceans
Earth’s atmosphere developed in stages:
• Hot gases escaped through volcanoes
and fissures.
• Free oxygen occurred as a result of
photosynthesis by cyanobacteria.
• Ozone began to accumulate in the
upper atmosphere.
• Water vapor condensed to form oceans.
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Components of Earth’s Oceans
Ocean floor encompasses continental
margins and deep ocean basins.
Continental margins are between
shorelines and deep ocean basins.
• Continental shelf—shallow, underwater
extension of the continent.
• Continental slope—marks boundary
between continental and oceanic crust.
• Continental rise—wedge of accumulated
sediment at base of continental slope.
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Components of Earth’s Oceans
The ocean bottom is etched with deep
canyons, trenches, and crevasses.
Underwater mountains rise upward from
the seafloor.
The deep-ocean basin:
• Basalt from seafloor spreading plus thick
accumulations of sediment
• Abyssal plains, ocean trenches, and
seamounts
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Components of Earth’s Oceans
The deep-ocean basin:
• Abyssal plains—flattest part of the ocean floor due
to accumulated sediment
• Ocean trenches—long, deep, steep troughs at
subduction zones
• Seamounts—elevated seafloor from volcanism
Mid-ocean ridges:
• Sites of seafloor spreading (volcanic and tectonic
activity)
• A global mid-ocean ridge system winds all around
the Earth
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Components of Earth’s Oceans
The deepest parts of the ocean are at the
ocean trenches near some of the continents.
The shallowest waters are in the middle of the
oceans around underwater mountains (midocean ridge system).
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Components of Earth’s Oceans
CHECK YOUR NEIGHBOR
Ocean trenches are the deepest parts of the ocean floor
because
A.
B.
C.
D.
that is where oceanic crust meets continental crust.
that is where subduction occurs.
no sediment accumulates in trenches.
all accumulated sediment settles in the abyssal plain.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley
Components of Earth’s Oceans
CHECK YOUR ANSWER
Ocean trenches are the deepest parts of the ocean floor
because
A.
B.
C.
D.
that is where oceanic crust meets continental crust.
that is where subduction occurs.
no sediment accumulates in trenches.
all accumulated sediment settles in the abyssal plain.
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Ocean Waves, Tides, and
Shorelines
Characteristics of waves—waves get their
energy from the wind.
• The crest is the peak of the wave.
• The trough is the low area between waves.
• Wave height is the distance between a trough
and a crest.
• Wavelength is the horizontal distance between
crests.
• Wave period is the time interval between the
passage of two successive crests.
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Ocean Waves, Tides, and
Shorelines
Height, length, and period of a wave
depend on:
• Wind speed
• Length of time wind has blown
• Fetch—the distance that the wind has
traveled across open water
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Ocean Waves, Tides, and
Shorelines
Waves on the ocean surface are orbital waves.
Wave energy moves forward: the disturbance
moves, not the water.
Occurs in the open sea in deep water.
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Ocean Waves, Tides, and
Shorelines
Waves at the shoreline:
• Shallow water; depth about one-half wavelength—wave
begins to “feel bottom”
• Wave grows higher as it slows and wavelength shortens
• Steep wave front collapses, wave breaks
• Turbulent water goes up the shore and forms surf
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Ocean Waves, Tides, and Shorelines
CHECK YOUR NEIGHBOR
When a wave approaches the shore, the water depth
decreases. This affects the wave by flattening its circular
motion,
A.
B.
C.
D.
decreasing its speed, and increasing distance between waves
and wave height.
increasing its speed and distance between waves, and
decreasing wave period.
decreasing its speed and distance between waves, causing wave
height to increase.
increasing its speed and distance between waves, causing wave
height to increase.
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Ocean Waves, Tides, and Shorelines
CHECK YOUR ANSWER
When a wave approaches the shore, the water depth
decreases. This affects the wave by flattening its circular
motion,
A.
B.
C.
D.
decreasing its speed, and increasing distance between waves
and wave height.
increasing its speed and distance between waves, and
decreasing wave period.
decreasing its speed and distance between waves, causing
wave height to increase.
increasing its speed and distance between waves, causing wave
height to increase.
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Ocean Waves, Tides, and
Shorelines
Surf forms erosional features:
• Beach
• Spit
• Barrier islands
• Lagoons
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Ocean Waves, Tides, and
Shorelines
Coral reefs are composed of actively
growing coral organisms.
Organisms secrete calcium carbonate as
they grow—that is what we see.
Many reefs survive on photosynthetic
algae.
Coral bleaching is an indicator of global
warming.
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Ocean Waves, Tides, and
Shorelines
Tides occur because of the differences in
the gravitational pull exerted by the
Moon on opposite sides of Earth.
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Ocean Waves, Tides, and
Shorelines
Because Earth spins on its axis once a
day, it should have two distinct tides 12
hours apart.
But because the Moon moves around
Earth, the times of the tides vary each
day.
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Ocean Waves, Tides, and
Shorelines
Alignment of the Sun, Earth, and Moon
causes spring tides—more dramatic
highs and lows.
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Ocean Waves, Tides, and
Shorelines
When the pull of the Sun and Moon are
perpendicular to each other, we get
neap tides—lower highs and higher
lows.
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Components of Atmosphere
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Components of Earth’s
Atmosphere
Earth’s atmosphere is divided into layers,
each with different characteristics:
• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Ionosphere
• Exosphere
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Components of Earth’s
Atmosphere
Troposphere:
• Lowest and thinnest layer
—16 km at equator, 8 km at poles
• 90% of the atmosphere’s mass
• Where weather occurs
—water vapor and clouds
• Temperature decreases with altitude
—6°C per kilometer
—Top of troposphere averages –50°C
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Components of Earth’s
Atmosphere
Stratosphere:
• Top of troposphere to 50 km above surface
• Ozone layer
—Absorbs harmful UV radiation
• Temperature increases because of ozone
absorption of UV radiation.
—Ranges from –50°C at base to 0°C at top
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Components of Earth’s
Atmosphere
Mesosphere:
• Extends from stratosphere to altitude of
80 km
• Temperature decreases with altitude
—Gases in this layer absorb very little UV
radiation.
—0°C at bottom to –90°C at top
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Components of Earth’s
Atmosphere
Thermosphere:
• Temperature increases with altitude
— Temperature is related to average speed
of gas molecules—very high speed gives
high temperatures
— Temperatures up to 1500°C
• Very low density of gas molecules
means very little heat absorption—it
would feel cold.
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Components of Earth’s
Atmosphere
Ionosphere:
• Electrified region within the thermosphere
and upper mesosphere
—Auroras—fiery displays of light near Earth’s
magnetic poles
Exosphere:
• The interface between Earth and space
• Beyond 500 km, atoms and molecules can
escape to space
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Components of Earth’s
Atmosphere
The average
temperature of
Earth’s
atmosphere varies
in a zig-zag
pattern with
altitude.
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Solar Energy
Solar radiation is electromagnetic energy
emitted by the Sun.
• Visible, short-wavelength radiation
Terrestrial radiation is reemitted solar
radiation from Earth’s surface.
• Infrared, longer-wavelength radiation
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Solar Energy
The Sun warms Earth’s ground, and the
ground, in turn, warms Earth’s
atmosphere.
• Earth’s temperature varies according to the
degree of solar intensity—the amount of
solar radiation per area.
• Where solar intensity is higher,
temperatures are higher.
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Solar Energy
Solar intensity is highest
where the Sun’s rays strike
Earth’s surface straight on.
• Flashlight beam at 90°
angle to the surface
• Equatorial regions
Solar intensity is weaker
where the Sun’s rays strike
Earth’s surface at an angle.
• Flashlight beam at an
angle
• Higher latitudes
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Solar Energy
Variation in solar intensity with latitude and the
tilt of the Earth’s axis helps to explain the
different seasons.
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Solar Energy
When the Sun’s rays are closest to
perpendicular at any spot on the Earth,
that region’s season is summer.
Six months later, as the rays fall upon the
same region more obliquely, the season is
winter.
In between are the seasons fall and spring.
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Solar Energy:
Global Warming
Human activities pump greenhouse gases
into the atmosphere: carbon dioxide,
methane, nitrous
oxide, ozone, CFCs.
The result is a
warming Earth.
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Driving Forces of Air Motion
Atmospheric pressure = force the
atmosphere exerts on an area of surface.
• Force = weight of air molecules above that
surface.
• At any level in the atmosphere, force = total
weight of air above that level.
• At higher elevations, fewer air molecules
above—atmospheric pressure is less.
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Driving Forces of Air Motion
CHECK YOUR NEIGHBOR
Atmospheric pressure is greatest near the Earth’s surface
because
A.
B.
C.
D.
of the weight of all the air above.
90% of Earth’s atmosphere is in the troposphere.
of warmer temperatures.
of water vapor.
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Driving Forces of Air Motion
CHECK YOUR ANSWER
Atmospheric pressure is greatest near the Earth’s surface
because
A.
B.
C.
D.
of the weight of all the air above.
90% of Earth’s atmosphere is in the troposphere.
of warmer temperatures.
of water vapor.
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Driving Forces of Air Motion
CHECK YOUR NEIGHBOR
What drives air from areas of high pressure to areas of low
pressure?
A.
B.
C.
D.
Convection currents.
Wind.
The pressure-gradient force.
Water vapor.
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Driving Forces of Air Motion
CHECK YOUR ANSWER
What drives air from areas of high pressure to areas of low
pressure?
A.
B.
C.
D.
Convection currents.
Wind.
The pressure-gradient force.
Water vapor.
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Driving Forces of Air Motion
Wind is air that flows horizontally from
higher pressure to lower pressure.
The greater the pressure gradient, the
stronger the wind.
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Driving Forces of Air Motion
Pressure differences are caused by
uneven heating of the Earth’s surface.
• Local differences in heating contribute to
small-scale local winds.
• Planet-scale differences occur because of
solar intensity variations—equatorial
regions have greater solar intensity than
polar regions.
—Differences contribute to global wind
patterns—prevailing winds.
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Driving Forces of Air Motion
Warm air characteristics:
• Warm air expands
• Warm air has lower density and lower pressure
Cool air characteristics:
• Cool air contracts
• Cool air has higher density and higher pressure
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Driving Forces of Air Motion
Local winds:
• Not all surfaces are heated equally.
• Example: Land heats and cools more
rapidly than water.
• Unequal heating results in pressure
differences. And pressure differences
result in wind.
Remember: Wind is air that flows
horizontally from higher pressure to
lower pressure.
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Driving Forces of Air Motion
CHECK YOUR NEIGHBOR
More energy is required to raise the temperature of water
than that of land. Once heated, water will retain the heat
longer than land. This concept is related to
A.
B.
C.
D.
expansion of warm air.
pressure differences of land and water.
water’s high specific heat capacity.
expansion of seawater.
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Driving Forces of Air Motion
CHECK YOUR ANSWER
More energy is required to raise the temperature of water
than that of land. Once heated, water will retain the heat
longer than land. This concept is related to
A.
B.
C.
D.
expansion of warm air.
pressure differences of land and water.
water’s high specific heat capacity.
expansion of seawater.
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Driving Forces of Air Motion
CHECK YOUR NEIGHBOR
At a hypothetical school yard there is a blacktop area and a
grassy area. On a particularly warm day, a small breeze
develops. Air moves from
A.
B.
C.
D.
the grassy area to the blacktop.
the blacktop to the grassy area.
low pressure to high pressure.
Not enough information.
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Driving Forces of Air Motion
CHECK YOUR ANSWER
At a hypothetical school yard there is a blacktop area and a
grassy area. On a particularly warm day, a small breeze
develops. Air moves from
A.
B.
C.
D.
the grassy area to the blacktop.
the blacktop to the grassy area.
low pressure to high pressure.
Not enough information.
Explanation:
Air above the blacktop is hotter (low pressure) than
air above the grassy area (higher pressure). Air
moves from high to low, so breeze will blow from
grassy area to blacktop.
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Global Circulation Patterns
Global circulation of the atmosphere
results from unequal
heating of Earth’s
surface and Earth’s
rotation.
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Global Circulation Patterns
At the equator, rising warm, moist air, low
pressure—doldrums
• Trade winds (0°– 30°)
At 30° N and S latitude, air cools and sinks—dry
air, high pressure—horse latitudes
• Deserts
• Westerlies (30°– 60°)
At 60° N and S latitude, cool, dry air meets
warm, moist air—low pressure (Polar Front)
• Polar easterlies (60°– 90°)
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Global Circulation Patterns
Earth’s rotation greatly affects the path of
moving air.
• Coriolis force: Moving bodies (such as air) deflect
to the right in the Northern Hemisphere, to the left
in the Southern Hemisphere.
• Deflection of wind varies according to speed and
latitude.
— Faster wind, greater deflection
— Deflection greatest at poles, decreases to zero at
equator
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Global Circulation Patterns
CHECK YOUR NEIGHBOR
The prevailing westerly winds are affected by the Coriolis
effect by the deflection of winds
A.
C.
to the right in the Northern Hemisphere and left in the Southern
Hemisphere.
to the left in the Northern Hemisphere and right in the Southern
Hemisphere.
laterally toward the poles.
D.
westward.
B.
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Global Circulation Patterns
CHECK YOUR ANSWER
The prevailing westerly winds are affected by the Coriolis
force by the deflection of winds
A.
C.
to the right in the Northern Hemisphere and left in the
Southern Hemisphere.
to the left in the Northern Hemisphere and right in the Southern
Hemisphere.
laterally toward the poles.
D.
westward.
B.
Explanation:
Winds are named for the direction from which they blow.
Westerlies blow from the west to the east.
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Global Circulation Patterns
CHECK YOUR NEIGHBOR
The prevailing winds in North America are westerly—they
blow from west to east. Westerly winds contribute to
cooling the western coast
A.
B.
C.
D.
in the winter and warming it in the summer.
in the summer and warming it in the winter.
so that the temperature is the same all year long.
and making temperature variations more extreme.
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Global Circulation Patterns
CHECK YOUR ANSWER
The prevailing winds in North America are westerly—they
blow from west to east. Westerly winds contribute to
cooling the western coast
A.
B.
C.
D.
in the winter and warming it in the summer.
in the summer and warming it in the winter.
so that the temperature is the same all year long.
and making temperature variations more extreme.
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Global Circulation Patterns
Factors that affect wind:
• The pressure gradient force: air moves from
high pressure to low pressure
• The Coriolis force: apparent deflection of
winds due to Earth’s rotation
• Frictional force: air moving close to ground
encounters friction
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Global Circulation Patterns
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Oceanic Circulation
Ocean currents are streams of water that move,
relative to the larger ocean.
Like the atmosphere, oceans have several
vertical layers: surface zone, transition zone,
and deep zone.
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Oceanic Circulation
Surface currents are created by wind.
Surface ocean currents correspond to the
directions of the prevailing winds.
Ekman transport: Coriolis force causes
water currents to deflect up to 45°.
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Oceanic Circulation:
Currents
Factors that influence ocean currents:
• For short distances, wind is strongest factor
• For longer distances, Coriolis forcet comes into
play:
—Coriolis causes surface currents to turn and
twist into semicircular whirls called gyres.
—Northern Hemisphere gyres rotate
clockwise.
—Southern Hemisphere gyres rotate
counterclockwise.
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Oceanic Circulation:
Currents
Gyres cause heat transport from equatorial regions to
higher latitudes.
The Gulf Stream current carries
vast quantities of warm
tropical water into higher
latitudes.
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Global Circulation Patterns:
The El Niño Condition
Years in which the Trade winds fail to
strengthen are called El Niño years.
El Niño Southern Oscillation influences climate
on both sides of the Pacific Ocean.
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Global Circulation Patterns:
Deep Water Currents
Deeper waters are driven not by winds but by gravity.
Polar water freezes, increasing the salinity of the liquid
water. Cold, salty water continuously sinks to the
ocean bottom.
The sinking water pushes deeper water out of the way,
causing the bottom water to flow outward along the
ocean floor.
A combination of deep-water mixing by ocean-floor tidal
stirring and upwelling due to favorable winds brings
the deep waters slowly back to the surface.
This conveyor-belt process may take thousands of
years.
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