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

Learning Objectives The 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 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 that water arrived from outer space through meteorite impacts. Figure 12.1a Volcanic eruptions provided water © 2012 John Wiley & Sons, Inc. All rights reserved.

The Oceans Figure 12.1 Comets © 2012 John Wiley & Sons, Inc. All rights reserved.

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

The Oceans Figure 12.1c Four major ocean basins © 2012 John Wiley & Sons, Inc. All rights reserved.

The Oceans Figure 12.2 Major rivers (plumes) joining the ocean © 2012 John Wiley & Sons, Inc. All rights reserved.

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 Layers in the Ocean Figure 12.3 Structure of the ocean © 2012 John Wiley & Sons, Inc. All rights reserved.

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

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

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

Where Ocean Meets Land Changes 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 © 2012 John Wiley & Sons, Inc. All rights reserved.

What a Geologists Sees: What Causes Tides? a. Bay of Fundy exceptional tidal range b. The causes of tides and tidal forces © 2012 John Wiley & Sons, Inc. All rights reserved.

Where Ocean Meets Land Figure 12.7 Rogue waves at sea © 2012 John Wiley & Sons, Inc. All rights reserved.

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 © 2012 John Wiley & Sons, Inc. All rights reserved. Where Ocean Meets Land Waves

Where Ocean Meets Land Figure 12.8b How waves change near shore © 2012 John Wiley & Sons, Inc. All rights reserved.

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

Figure Ocean City, Maryland © 2012 John Wiley & Sons, Inc. All rights reserved.

Where Ocean Meets Land Shorelines 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 Coastal landforms © 2012 John Wiley & Sons, Inc. All rights reserved.

Beach Wave-washed sediment along a coast Figure Expensive follies © 2012 John Wiley & Sons, Inc. All rights reserved. Where Ocean Meets Land Shorelines 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 Barrier island, spit, lagoon © 2012 John Wiley & Sons, Inc. All rights reserved. Where Ocean Meets Land Shorelines 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 Coral reef © 2012 John Wiley & Sons, Inc. All rights reserved. Where Ocean Meets Land Shorelines and Coastal Landforms

The Atmosphere Origin of Earth’s atmosphere: Volcanic eruptions Comets Figure 12.15a Origin of the atmosphere © 2012 John Wiley & Sons, Inc. All rights reserved.

Earth’s secondary atmosphere: Oxygen released by photosynthetic organisms to produce “breathable” air Figure 12.15b Algal mats © 2012 John Wiley & Sons, Inc. All rights reserved. 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 © 2012 John Wiley & Sons, Inc. All rights reserved. The Atmosphere Composition of Earth’s Atmosphere

© 2012 John Wiley & Sons, Inc. All rights reserved. Figure 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 Four layers of atmosphere © 2012 John Wiley & Sons, Inc. All rights reserved. The Atmosphere Layers 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 © 2012 John Wiley & Sons, Inc. All rights reserved. The Atmosphere Layers in the Atmosphere

Earth’s Atmosphere Figure 12.18b Greenhouse effect © 2012 John Wiley & Sons, Inc. All rights reserved.

Earth’s Atmosphere Figure A shield against radiation © 2012 John Wiley & Sons, Inc. All rights reserved.

Earth’s Atmosphere Figure Who gets the most sunlight? © 2012 John Wiley & Sons, Inc. All rights reserved.

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 Global atmospheric circulation © 2012 John Wiley & Sons, Inc. All rights reserved. The Atmosphere Movement in the Atmosphere

Where Ocean Meets Atmosphere Average daily temperatures in different temperature zones Figure Global air temperature distribution © 2012 John Wiley & Sons, Inc. All rights reserved.

Where Ocean Meets Atmosphere Figure (a, b) On the track of a hurricane © 2012 John Wiley & Sons, Inc. All rights reserved.

Where Ocean Meets Atmosphere El Niño and La Niña

© 2012 John Wiley & Sons, Inc. All rights reserved. Where Ocean Meets Atmosphere El Niño and La Niña