Chapter 5Chapter 5Ecosystems and the Physical Ecosystems and the Physical EnvironmentEnvironment

Overview of Chapter 5Overview of Chapter 5o Biogeochemical CyclesBiogeochemical Cycleso Solar RadiationSolar Radiationo The AtmosphereThe Atmosphereo The Global OceanThe Global Oceano Weather and ClimateWeather and Climateo Internal Planetary ProcessesInternal Planetary Processes

Biogeochemical CyclesBiogeochemical Cycleso Matter moves between Matter moves between

ecosystems, biotic & abiotic ecosystems, biotic & abiotic environments, and environments, and organismsorganisms• Unlike energyUnlike energy

o Biogeochemical cycling Biogeochemical cycling involves involves • Biological, geologic and Biological, geologic and

chemical interactionschemical interactionso Five major cycles: Five major cycles:

• Carbon, Nitrogen, Phosphorus, Carbon, Nitrogen, Phosphorus, Sulfur and Water (hydrologic)Sulfur and Water (hydrologic)

The Carbon CycleThe Carbon Cycle

The Nitrogen CycleThe Nitrogen Cycle

The Phosphorus CycleThe Phosphorus Cycle

The Sulfur CycleThe Sulfur Cycle

The Water (Hydrologic) CycleThe Water (Hydrologic) Cycle

Solar RadiationSolar Radiation

o 69% of incoming solar 69% of incoming solar radiation is absorbed by radiation is absorbed by atmosphere and earthatmosphere and earth• Remainder is reflectedRemainder is reflected

o AlbedoAlbedo• The reflectance of solar The reflectance of solar

energy off earth’s surfaceenergy off earth’s surface• Dark colors = low albedoDark colors = low albedo

• Forests and oceanForests and ocean• Light colors = high albedoLight colors = high albedo

• Ice capsIce caps

o Sun provides energy for life, powers Sun provides energy for life, powers biogeochemical cycles, and determines climatebiogeochemical cycles, and determines climate

Temperature Changes with LatitudeTemperature Changes with Latitudeo Solar energy does not hit earth Solar energy does not hit earth

uniformlyuniformly• Due to earth’s spherical shape and tiltDue to earth’s spherical shape and tiltEquator (a)Equator (a)

High concentration High concentration Little Reflection Little Reflection High TemperatureHigh Temperature

Closer to Poles Closer to Poles (c)(c)

Low Low concentration concentration

Higher Higher Reflection Low Reflection Low

TemperatureTemperature

From (a) to (c)From (a) to (c)In diagram In diagram belowbelow

Temperature Changes with Temperature Changes with SeasonSeason

o Seasons Seasons determined determined by earth’s tilt by earth’s tilt (23.5°)(23.5°)

o Causes each Causes each hemisphere to hemisphere to tilt toward the tilt toward the sun for half sun for half the yearthe year

o Northern Hemisphere tilts towards the sun from Northern Hemisphere tilts towards the sun from March 21- September 22 (warm season)March 21- September 22 (warm season)

The AtmosphereThe Atmosphereo Invisible layer of gases Invisible layer of gases

that envelopes earththat envelopes eartho ContentContent

• 21% Oxygen21% Oxygen• 78% Nitrogen78% Nitrogen• 1% Argon, Carbon dioxide, 1% Argon, Carbon dioxide,

Neon and HeliumNeon and Heliumo Density decreases with Density decreases with

distance from earthdistance from eartho Shields earth from high Shields earth from high

energy radiationenergy radiation

Atmospheric LayersAtmospheric Layerso Troposphere (0-10km)Troposphere (0-10km)

• Where weather occursWhere weather occurs• Temperature decreases with Temperature decreases with

altitudealtitudeo Stratosphere (10-45km)Stratosphere (10-45km)

• Temperature increases with Temperature increases with altitude- very stablealtitude- very stable

• Ozone layer absorbs UVOzone layer absorbs UVo Mesosphere (45-80km)Mesosphere (45-80km)

• Temperature decreases with Temperature decreases with altitudealtitude

Atmospheric LayersAtmospheric Layerso Thermosphere (80-500km)Thermosphere (80-500km)

• Gases in thin air absorb x-Gases in thin air absorb x-rays and short-wave UV rays and short-wave UV radiation = very hotradiation = very hot

• Source of auroraSource of aurorao Exosphere (500km and up)Exosphere (500km and up)

• Outermost layerOutermost layer• Atmosphere continues to thin Atmosphere continues to thin

until converges with until converges with interplanetary spaceinterplanetary space

Atmospheric CirculationAtmospheric Circulation

o Near EquatorNear Equator• Warm air rises, cools Warm air rises, cools

and splits to flow and splits to flow towards the polestowards the poles

• ~30°N&S sinks back to ~30°N&S sinks back to surfacesurface

• Air moves along surface Air moves along surface back towards equatorback towards equator

o This occurs at higher This occurs at higher latitudes as welllatitudes as well• Moves heat from Moves heat from

equator to the polesequator to the poles

Surface WindsSurface Winds

o Large winds due in Large winds due in part to pressures part to pressures caused by global caused by global circulation of aircirculation of air• Left side of diagramLeft side of diagram

o Winds blow from Winds blow from high to low pressurehigh to low pressure• Right side of Right side of

diagramdiagram

LowLow

LowLow

LowLow

HighHigh

HighHigh

HighHigh

HighHigh

Coriolis EffectCoriolis Effect

o Earth’s rotation influences direction of Earth’s rotation influences direction of windwind• Earth rotates from East to WestEarth rotates from East to West• Deflects wind from straight-line pathDeflects wind from straight-line path

o Coriolis EffectCoriolis Effect• Influence of the earth’s rotation on movement Influence of the earth’s rotation on movement

of air and fluidsof air and fluids• Turns them Turns them RightRight in the Northern Hemisphere in the Northern Hemisphere• Turns them Turns them LeftLeft in the Southern Hemisphere in the Southern Hemisphere

Coriolis EffectCoriolis Effecto Visualize it as a Merry-Go-Round (see Visualize it as a Merry-Go-Round (see

below)below)

Global Ocean CirculationGlobal Ocean Circulationo Prevailing winds produce ocean Prevailing winds produce ocean

currents and generate gyrescurrents and generate gyreso Example: the North Atlantic OceanExample: the North Atlantic Ocean

• Trade windsTrade winds blow west blow west• Westerlies Westerlies blow eastblow east• Creates a clockwise gyre in the North Creates a clockwise gyre in the North

AtlanticAtlantico Circular pattern influenced by coriolis Circular pattern influenced by coriolis

effecteffect

Global Ocean CirculationGlobal Ocean Circulation

Trade windsTrade winds

WesterliesWesterlies

Position of LandmassesPosition of Landmasses

Very little land in Very little land in the Southern the Southern HemisphereHemisphere

Large landmasses Large landmasses in the Northern in the Northern Hemisphere help Hemisphere help to dictate ocean to dictate ocean currents and flowcurrents and flow

Vertical Mixing of OceanVertical Mixing of Ocean

Ocean Interaction with Atmosphere- Ocean Interaction with Atmosphere- ENSOENSO

o El Niño-Southern Oscillation (ENSO)El Niño-Southern Oscillation (ENSO)• Def: periodic large scale warming of surface waters of Def: periodic large scale warming of surface waters of

tropical eastern Pacific Oceantropical eastern Pacific Oceano Alters ocean and atmospheric circulation Alters ocean and atmospheric circulation

patternspatternso Normal conditions- westward blowing tradewinds Normal conditions- westward blowing tradewinds

keep warmest water in western Pacifickeep warmest water in western Pacifico ENSO conditions- trade winds weaken and warm ENSO conditions- trade winds weaken and warm

water expands eastward to South Americawater expands eastward to South America• Big effect on fishing industry off South AmericaBig effect on fishing industry off South America

ENSO Climate PatternsENSO Climate Patterns

Weather and ClimateWeather and Climateo WeatherWeather

• The conditions in the atmosphere at a The conditions in the atmosphere at a given place and timegiven place and time

• Temperature, precipitation, cloudiness, etc.Temperature, precipitation, cloudiness, etc.o ClimateClimate

• The average weather conditions that occur The average weather conditions that occur in a place over a period of yearsin a place over a period of years

• 2 most important factors: temperature and 2 most important factors: temperature and precipitationprecipitation

• Earth has many climatesEarth has many climates

Rain ShadowsRain Shadowso Mountains force humid air to riseMountains force humid air to riseo Air cools with altitude, clouds form and Air cools with altitude, clouds form and

precipitation occurs (windward side)precipitation occurs (windward side)o Dry air mass moves down opposite Dry air mass moves down opposite

leeward side of mountainleeward side of mountain

TornadoesTornadoeso Powerful funnel of air associated with a Powerful funnel of air associated with a

severe thunderstormsevere thunderstormo FormationFormation

• Mass of cool dry air collides with warm humid Mass of cool dry air collides with warm humid airair

• Produces a strong updraft of spinning air under Produces a strong updraft of spinning air under a clouda cloud

• Spinning funnel becomes tornado when it Spinning funnel becomes tornado when it descends from clouddescends from cloud

o Wind velocity= up to 300mphWind velocity= up to 300mpho Width ranges from 1m to 3.2kmWidth ranges from 1m to 3.2km

Hurricanes, Typhoons, CyclonesHurricanes, Typhoons, Cycloneso Giant rotating tropical stormsGiant rotating tropical stormso Wind >119km per hourWind >119km per houro FormationFormation

• Strong winds pick up moisture over warm surface Strong winds pick up moisture over warm surface waters waters

• Starts to spin due to Earth’s Starts to spin due to Earth’s rotationrotation• Spin causes upward spiral Spin causes upward spiral of cloudsof clouds

o Damaging on landDamaging on land• High windsHigh winds• Storm surgesStorm surges

Internal Planetary ProcessesInternal Planetary Processeso Layers of the earthLayers of the earth

• LithosphereLithosphere• Outermost rigid rock layer composed of platesOutermost rigid rock layer composed of plates

• AsthenosphereAsthenosphere• Lower mantle comprised of hot soft rockLower mantle comprised of hot soft rock

o Plate Tectonics- study of the processes Plate Tectonics- study of the processes by which the lithospheric plates move by which the lithospheric plates move over the asthenosphereover the asthenosphere

o Plate Boundary- where 2 plates meetPlate Boundary- where 2 plates meet• Common site of earthquakes and volcanoesCommon site of earthquakes and volcanoes

Plates and Plate BoundariesPlates and Plate Boundaries

Types of Plate BoundariesTypes of Plate Boundaries

o Divergent Plate Divergent Plate Boundary-2 plates Boundary-2 plates move apartmove apart

o Convergent Plate Boundary-Convergent Plate Boundary-2 plates move together 2 plates move together (may get subduction)(may get subduction)

Types of Plate BoundariesTypes of Plate Boundaries

o Transform Transform Plate Plate Boundary- 2 Boundary- 2 plates move plates move horizontally in horizontally in opposite, opposite, parallel parallel directionsdirections

EarthquakesEarthquakeso Caused by the release of accumulated Caused by the release of accumulated

energy as rocks in the lithosphere energy as rocks in the lithosphere suddenly shift or breaksuddenly shift or break• Occur along faultsOccur along faults• Energy released as seismic waveEnergy released as seismic wave

o Focus- the site where the earthquake Focus- the site where the earthquake originates below the surfaceoriginates below the surface

o Epicenter- located on the earth’s surface, Epicenter- located on the earth’s surface, directly above the focusdirectly above the focus

o Richter scale and the moment magnitude Richter scale and the moment magnitude scales are used to measure the magnitudescales are used to measure the magnitude

TsunamiTsunamio Giant undersea wave caused by an Giant undersea wave caused by an

earthquake, volcanic eruption or landslideearthquake, volcanic eruption or landslide• Travel > 450mphTravel > 450mph

o Tsunami wave may be 1m deep in oceanTsunami wave may be 1m deep in ocean• Becomes 30.5m high on shoreBecomes 30.5m high on shore

o Magnitude 9.3 earthquake in Indian OceanMagnitude 9.3 earthquake in Indian Ocean• Triggered tsunami that killed over 230,000 Triggered tsunami that killed over 230,000

people in South Asia and Africapeople in South Asia and Africa