Earth’s Many Cycles Chapter 18 Great Idea: All matter above and beneath Earth’s surface moves in cycles. 1

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 4

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

– HotÆcold – Sources

• Sun • Geothermal processes 5

iClicker Question • What are the Earth’s two primary sources of heat energy? – A – B – C

solar energy and friction the Sun and geothermal processes atmospheric friction and forest fires

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iClicker Question • Many of Earth’s cycles are driven by: – A – B – C

Earth’s rotation tilt of the Earth’s axis 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 B C D

aqueous cycle drought/drench ratio hydrologic cycle repository balance 16

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

A B C D

less than 1 5 67 more than 98

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

A B C D

less than 1 5 67 more than 98

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iClicker Question • The ocean is getting saltier. – A – B

True False

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iClicker Question • What process removes atoms from the ocean? – A – B – C

photosynthesis digestion by fishes and animals chemical reactions

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iClicker Question • During an ice age, sea levels: – A – B – C

drop rise 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 24 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 31

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 B C D

north to south south to north east to west west to east

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iClicker Question • Earth’s atmospheric cycle is not strongly influenced by other global cycles. – A – B

True False

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iClicker Question In what part of the atmosphere does weather occur? A hydrosphere B stratosphere C ionosphere D troposphere E all of the above 39

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. 40

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 44

Metamorphic Rocks • Metamorphic rock – Pressure and heat • Not enough heat to melt

• Examples – Slate – Schists – Gneisses – Quartzite 45

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 48

• Folds – bends in layered bedrock

• Anticline

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• Syncline \/ 49

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 – B

True False

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iClicker Question • The first type of rock to appear on Earth was: – A – B – C

igneous sedimentary metamorphic

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iClicker Question • Which type of rock is made of grains of material worn off previous rocks? – A – B – C

igneous sedimentary 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 – B – C

igneous rocks sedimentary rocks 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 – B

True False

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iClicker Question Rocks formed from layers of fine material that have been compressed under water are called A igneous rocks B sedimentary rocks C metamorphic rocks D fault rocks E scarp rocks 57

iClicker Question • Which of Earth’s cycles is most interesting to you? – A – B – C

atmospheric hydrologic rock

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