Chapter 12: The Ocean and the Atmosphere Chandeleur Islands, Louisiana © 2012 John Wiley & Sons,...

Chapter 12: The Ocean and the Atmosphere

Chandeleur Islands, Louisiana© 2012 John Wiley & Sons, Inc. All rights reserved.

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.

© 2012 John Wiley & Sons, Inc. All rights reserved.

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


The Oceans

Figure 12.1 Comets


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.


The Oceans

Figure 12.1c Four major ocean basins


The Oceans

Figure 12.2 Major rivers (plumes) joining 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 OceanLayers in the Ocean

Figure 12.3 Structure of the ocean


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


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


The Ocean


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


What a Geologists Sees:What Causes Tides?

a. Bay of Fundy exceptional tidal range

b. The causes of tides and tidal forces


Where Ocean Meets Land

Figure 12.7 Rogue waves at sea


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


Where Ocean Meets LandWaves


Figure 12.8b How waves change near shore


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.



Figure 12.10 Ocean City, Maryland


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


•Beach• Wave-washed sediment along a coast

Figure 12.12 Expensive follies



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



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



The Atmosphere

Origin of Earth’s atmosphere:•Volcanic eruptions•Comets

Figure 12.15a Origin of the atmosphere


Earth’s secondary atmosphere:•Oxygen released by photosynthetic organisms to produce “breathable” air

Figure 12.15b Algal mats


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


The AtmosphereComposition of Earth’s Atmosphere


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


The AtmosphereLayers in the Atmosphere

Earth’s Atmosphere

Figure 12.18b Greenhouse effect



Figure 12.19 A shield against radiation



Figure 12.21 Who gets the most sunlight?


• 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


The AtmosphereMovement in the Atmosphere

Where Ocean Meets Atmosphere

Average daily temperatures in different temperature zones

Figure 12.24 Global air temperature distribution


Where Ocean Meets Atmosphere

Figure 12.25 (a, b) On the track of a hurricane



Where Ocean Meets AtmosphereEl Niño and La Niña

Chapter 12: The Ocean and the Atmosphere Chandeleur Islands, Louisiana © 2012 John Wiley & Sons,...

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