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Earth’s Many Cycles

Chapter 18

Great Idea:All matter above and beneath Earth’s

surface moves in cycles.

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Chapter Outline

• Cycles Small and Large• The Hydrologic Cycle• The Atmospheric Cycle• The Rock Cycle

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Cycles Small and Large

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Recycling

• Where did the aluminum can go?• Atoms last virtually forever

–Different forms• Lava flow bonded to oxygen• Solid rock• Soil• Aluminum metal

• Recycling saves energy

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The Nature of Earth’s Cycle

• Earth materials move in cycles• A change in one cycle affects the others• Atoms constantly moving and recycling

– Reservoirs – Hydrologic cycle– Atmospheric cycle– Rock cycle

• Heat– Hot cold– Sources

• Sun• Geothermal processes

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iClicker Question

• What are the Earth’s two primary sources of heat energy?

– A solar energy and friction– B the Sun and geothermal

processes– C atmospheric friction and forest

fires

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iClicker Question

• Many of Earth’s cycles are driven by:

– A Earth’s rotation– B tilt of the Earth’s axis– C the tendency of heat to spread

out

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The Hydrologic Cycle

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Reservoirs of Water

• Amount of water on earth is fixed• Major repositories

– Ice caps– Glaciers

• Unseen reservoirs– Groundwater

• aquifers

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Movements of Water Between Reservoirs

• Hydrologic cycle– Short-term transfer of water between ocean and land

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The path of groundwater

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Ocean Currents

• Redistribute heat across planet

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Chemical Cycles in the Oceans

• Chemicals in constant motion• Saltiness

–Constant over several hundred million years

–Primarily determined by Na+ and Cl- ions–Residence time

• Chemical cycle

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Ice Ages

• Ice Age– Water locked in

glaciers– Glaciers advance

from poles• Current ice age

– Interglacial period• Earth’s total water

is fixed– Ice caps, glaciers

grow– Sea level drops

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Milankovitch Cycles• Milankovitch

– Serbian civil engineer– Relationship between earth and sun are affected by

variations in earth’s rotation and orbit

• Precession• Change in angle of axis of rotation

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iClicker Question

• The combination of processes by which water moves from repository to repository above, below, and on the Earth’s surface is called the:

– A aqueous cycle– B drought/drench ratio– C hydrologic cycle– D repository balance

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iClicker Question

• What percent of the Earth’s water is readily available for human use?

– A less than 1– B 5– C 67– D more than 98

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iClicker Question

• What percent of the Earth’s fresh water is stored as groundwater?

– A less than 1– B 5– C 67– D more than 98

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iClicker Question

• The ocean is getting saltier.– A True– B False

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iClicker Question

• What process removes atoms from the ocean?

– A photosynthesis– B digestion by fishes and animals– C chemical reactions

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iClicker Question

• During an ice age, sea levels:– A drop– B rise– C remain constant

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The Atmospheric Cycle

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Atmosphere

• Composition– Nitrogen (78%), Oxygen (21%), Argon, Water

Vapor, CO2, Methane, other

• Atmospheric Pressure– pressure exerted by atmosphere

• Warming– Sun - solar constant is not really constant– greenhouse effect

• warming due to the transparency of a substance to radiation at visible wavelengths and opacity to infrared radiation

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The Greenhouse Effect• Solar energy is the

energy source for the atmosphere

• In the greenhouse effect, some of this energy is trapped by infrared absorbing gases in the atmosphere, raising the Earth’s surface temperature above what it would be if there was no greenhouse effect

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Industrial chemicals released into the atmosphere have damaged the

ozone layer in the stratosphere

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The Earth’s atmosphere has changed substantially over time

• The Earth’s atmosphere differs from those of the other terrestrial planets in its chemical composition, circulation pattern, and temperature profile

• The Earth’s atmosphere changed from being mostly water vapor to being rich in carbon dioxide

• A strong greenhouse effect kept the Earth warm enough for water to remain liquid and to permit the evolution of life

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Structure of the Atmosphere

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Air Masses: Reservoirs of the Atmosphere

• Air mass–Uniform

temperature and moisture

• Weather–State of the

atmosphere• Climate

–Long-term average of weather

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Weather• Five variables define

state of atmosphere– Temperature

• Ground level

– Air pressure• Decreases with altitude• Jet stream

– Humidity• Atmospheric water content

– Cloudiness• Concentration of water droplets

– Prevailing winds• Consequence of atmospheric

convection

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The General Circulation of the Atmosphere

• Circulation powered by Sun–Air heated and rises–Cools and sinks

• Prevailing winds–Caused by earth’s

rotation

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Common Storms and Weather Patterns

• Severe weather–Tropical storms

• Hurricanes• typhoons

–Tornadoes

• Weather cycle–El Nino

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Climate

• Little change over short periods• Influences on climate

–Large bodies of water–Ocean currents–Mountain ranges

• Earth’s climate–Movement of tectonic plates

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Understanding Climate

• Long-term climate–Oceans–Mountains–Sunlight

• Amount radiated back to space

• Prediction–Global circulation models

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iClicker Question

• The weather patterns in much of the Northern Hemisphere move, in general, from:

– A north to south– B south to north– C east to west– D west to east

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iClicker Question

• Earth’s atmospheric cycle is not strongly influenced by other global cycles.

– A True– B False

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iClicker Question

In what part of the atmosphere does weather occur?

A hydrosphereB stratosphereC ionosphereD troposphereE all of the above

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iClicker Question

The greenhouse effect occurs largely because

A a gas is transparent to visible light and opaque to infrared radiation.

B a gas is transparent to infrared radiation and opaque to ultraviolet radiation.

C ozone is transparent to ultraviolet radiation and opaque to infrared radiation.

D methane is transparent to infrared radiation and opaque to visible light.

E the sun emits more infrared radiation than ultraviolet radiation.

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The Rock Cycle

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Rock Cycle Overview

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Igneous Rocks

• Igneous Rocks–Solidify from hot liquid

• Types–Extrusive

• Solidify at surface

– Intrusive• Solidify below surface

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Sedimentary Rocks

• Sedimentary rock– From grains of weathered

rock

• Formation– Compaction– Cementation

• Examples– Sandstone– Shale– Limestone

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Metamorphic Rocks

• Metamorphic rock–Pressure and heat

• Not enough heat to melt

• Examples–Slate–Schists–Gneisses –Quartzite

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The Story of Marble

• Marble–Metamorphic rock

• Process of formation–Begin as limestone–Subjected to heat and

pressure–Erosion exposes rocks

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Surface Building Processes• Faulting

– formation of a crack caused by relative movement of rock on either side of a fracture• different types - normal, reverse, thrust

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Mountains

• “elevated parts of the Earth’s crust that rise abruptly above the surrounding surface”

• Causes– folding, faulting,

volcanic activity

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• Folds–bends in layered

bedrock

• Anticline /\

• Syncline\/

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Volcanoes• “hill or mountain formed by the extrusion of lava

or rock fragments from magma below”• Different types

– shield, cinder cone, composite (composite shown)

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Earthquakes

• Defined as “quaking, shaking, vibrating, or upheaval of the ground”

• Earthquake causes– elastic rebound

theory

• Intensity measure– Richter Magnitude

• not linear scale

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iClicker Question

• When the Earth formed there were no rocks.

– A True– B False

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iClicker Question

• The first type of rock to appear on Earth was:

– A igneous– B sedimentary– C metamorphic

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iClicker Question

• Which type of rock is made of grains of material worn off previous rocks?

– A igneous– B sedimentary– C metamorphic

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iClicker Question

• Rocks that are buried deep within the Earth and then subjected to intense pressure and heat turn into:

– A igneous rocks– B sedimentary rocks– C metamorphic rocks

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iClicker Question

• The Earth’s cycles operate on very different time scales and therefore have little influence on each other.

– A True– B False

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iClicker Question

Rocks formed from layers of fine material that have been compressed under water are called

A igneous rocksB sedimentary rocksC metamorphic rocksD fault rocksE scarp rocks

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iClicker Question

• Which of Earth’s cycles is most interesting to you?

– A atmospheric– B hydrologic– C rock