Post on 31-Dec-2015
Chapter 12: The Ocean and the Atmosphere
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Learning ObjectivesThe ocean
• Explain the origin and structure of Earth’s oceans.
Where ocean meets land• Describe the effects of tides and waves on
coastal landforms and reefs.
The atmosphere• Identify the four layers of Earth’s atmosphere
and their role in protecting and warming Earth.
Where ocean meets atmosphere• Summarize how the ocean and the atmosphere
interact to regulate Earth’s climate.
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The OceansOcean 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 that
water arrived from outer space through meteorite impacts.
Figure 12.1a Volcanic eruptions provided water
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The Oceans
Figure 12.1 Comets
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The OceansOcean Basins
Earth has four 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.
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The Oceans
Figure 12.1c Four major ocean basins
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The Oceans
Figure 12.2 Major rivers (plumes) joining the ocean
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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 OceanLayers in the Ocean
Figure 12.3 Structure of the ocean
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The OceanOcean Currents
Surface currents:•Caused by winds that drag the surface of the water•Extends to about 50 to 100 meters deep•Antarctic Bottom Water and the Gulf Stream Figure 12.4 Surface ocean currents
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The OceanOcean Currents
Thermohaline circulation:
• “The great ocean conveyor belt” • North Atlantic Deep
Water• Antarctic Bottom
water• The Gulf Stream
• Driven by differences in temperature, salinity, and density
Figure 12.5 Ocean conveyor belt
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The Ocean
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Where Ocean Meets LandChanges in Sea Level
Global volume changes•Nearly imperceptible in human lifetime•Account for great change in position of shoreline over geologic time•Tides• Daily cycle of raising and
falling sea level that results from the gravitational action of the Moon, Sun, and Earth
Figure 12.6a Bering land bridge; 20,000 years ago
Figure 12.6 Bering Strait; present
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What a Geologists Sees:What Causes Tides?
a. Bay of Fundy exceptional tidal range
b. The causes of tides and tidal forces
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Where Ocean Meets Land
Figure 12.7 Rogue waves at sea
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Waves•Ocean waves receive energy from wind•Surf
• The “broken,” turbulent water found between a line of breakers and shore
•Rip currents•Wave fraction
Figure 12.8a How waves change near shore
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Where Ocean Meets LandWaves
Where Ocean Meets Land
Figure 12.8b How waves change near shore
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Erosion and transport of sediment by waves
• Longshore current• A current within the surf
zone that flows parallel to the coast
• Beach drift• Movement of particles
along a beach as they are driven up and down beach slope by wave action
Figure 9a Longshore current
Figure 9b Swash and backswash© 2012 John Wiley & Sons, Inc. All rights reserved.
Where Ocean Meets Land
Where Ocean Meets Land
Figure 12.10 Ocean City, Maryland
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Where Ocean Meets LandShorelines and Coastal Landforms
Three types:•Rocky coasts•Beach and barrier island coasts•Coral reefs
Rocky coasts•Wave-cut cliff: A coastal cliff cut by wave action at the base of a rocky coast
Figure 12.11 Coastal landforms
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•Beach• Wave-washed sediment along a coast
Figure 12.12 Expensive follies
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Where Ocean Meets LandShorelines and Coastal Landforms
Beaches and barrier islands•Barrier island• A long, narrow,
sandy island offshore and parallel to a lowland coast
•Spits•Lagoon•Estuaries Figure 12.13 Barrier island, spit,
lagoon
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Where Ocean Meets LandShorelines and Coastal Landforms
Coral reefs• Reef
• 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
Figure 12.14 Coral reef
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Where Ocean Meets LandShorelines and Coastal Landforms
The Atmosphere
Origin of Earth’s atmosphere:•Volcanic eruptions•Comets
Figure 12.15a Origin of the atmosphere
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Earth’s secondary atmosphere:•Oxygen released by photosynthetic organisms to produce “breathable” air
Figure 12.15b Algal mats
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The Atmosphere
•Air• Gaseous envelope
surrounding Earth• Composed of 78%
nitrogen, 21% oxygen, and trace amounts of other gases found in Earth’s atmosphere
Figure 12.15c Atmosphere
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The AtmosphereComposition of Earth’s Atmosphere
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Figure 12.16 What air is made of
The 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 and thermosphere Figure 12.17 Four layers of
atmosphere© 2012 John Wiley & Sons, Inc. All rights reserved.
The AtmosphereLayers in the Atmosphere
•Greenhouse effect• The process through
which long-wavelength (infrared) heat energy is absorbed by gases in the atmosphere
• Absorption of energy warms Earth’s surface
Figure 12.18a Greenhouse effect
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The AtmosphereLayers in the Atmosphere
Earth’s Atmosphere
Figure 12.18b Greenhouse effect
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Earth’s Atmosphere
Figure 12.19 A shield against radiation
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Earth’s Atmosphere
Figure 12.21 Who gets the most sunlight?
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• Convection currents• Global circulation organizes
itself into 3 convection cells• Coriolis force
• An effect due to Earth’s rotation, which causes a freely moving body to veer from a straight path
Figure 12.22 Global atmospheric circulation
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The AtmosphereMovement in the Atmosphere
Where Ocean Meets Atmosphere
Average daily temperatures in different temperature zones
Figure 12.24 Global air temperature distribution
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Where Ocean Meets Atmosphere
Figure 12.25 (a, b) On the track of a hurricane
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Where Ocean Meets AtmosphereEl Niño and La Niña
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Where Ocean Meets AtmosphereEl Niño and La Niña