Chapter 5 Ecosystems and the Physical Environment

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Chapter 5Ecosystems and the Physical Environment
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Overview of Chapter 5

• Biogeochemical Cycles
• Solar Radiation
• The Atmosphere
• The Global Ocean
• Weather and Climate
• Internal Planetary Processes

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Biogeochemical Cycles

• Matter moves between ecosystems, biotic abiotic
  environments, and organisms
• Unlike energy
• Biogeochemical cycling involves
• Biological, geologic and chemical interactions
• Five major cycles
• Carbon, Nitrogen, Phosphorus, Sulfur and Water
  (hydrologic)

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The Carbon Cycle
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The Nitrogen Cycle
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Solar Radiation

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

• 69 of incoming solar radiation is absorbed by
  atmosphere and earth
• Remainder is reflected
• Albedo
• The reflectance of solar energy off earths
  surface
• Dark colors low albedo
• Forests and ocean
• Light colors high albedo
• Ice caps

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The Phosphorus Cycle
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The Sulfur Cycle
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The Water (Hydrologic) Cycle
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Temperature Changes with Latitude

• Solar energy does not hit earth uniformly
• Due to earths spherical shape and tilt

Equator (a) High concentration Little Reflection
High Temperature
Closer to Poles (c) Low concentration Higher
Reflection Low Temperature
From (a) to (c)
In diagram below
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Temperature Changes with Season

• Seasons determined by earths tilt (23.5)
• Causes each hemisphere to tilt toward the sun for
  half the year

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

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The Atmosphere

• Invisible layer of gases that envelopes earth
• Content
• 21 Oxygen
• 78 Nitrogen
• 1 Argon, Carbon dioxide, Neon and Helium
• Density decreases with distance from earth
• Shields earth from high energy radiation

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Atmospheric Layers

• Troposphere (0-10km)
• Where weather occurs
• Temperature decreases with altitude
• Stratosphere (10-45km)
• Temperature increases with altitude- very stable
• Ozone layer absorbs UV
• Mesosphere (45-80km)
• Temperature decreases with altitude

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Atmospheric Layers

• Thermosphere (80-500km)
• Gases in thin air absorb x-rays and short-wave UV
  radiation very hot
• Source of aurora
• Exosphere (500km and up)
• Outermost layer
• Atmosphere continues to thin until converges with
  interplanetary space

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Atmospheric Circulation

• Near Equator
• Warm air rises, cools and splits to flow towards
  the poles
• 30NS sinks back to surface
• Air moves along surface back towards equator
• This occurs at higher latitudes as well
• Moves heat from equator to the poles

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Surface Winds
High

• Large winds due in part to pressures caused by
  global circulation of air
• Left side of diagram
• Winds blow from high to low pressure
• Right side of diagram

Low
High
Low
High
Low
High
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Coriolis Effect

• Earths rotation influences direction of wind
• Earth rotates from East to West
• Deflects wind from straight-line path
• Coriolis Effect
• Influence of the earths rotation on movement of
  air and fluids
• Turns them Right in the Northern Hemisphere
• Turns them Left in the Southern Hemisphere

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Coriolis Effect

• Visualize it as a Merry-Go-Round (see below)

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Global Ocean Circulation

• Prevailing winds produce ocean currents and
  generate gyres
• Example the North Atlantic Ocean
• Trade winds blow west
• Westerlies blow east
• Creates a clockwise gyre in the North Atlantic
• Circular pattern influenced by coriolis effect

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Global Ocean Circulation
Westerlies
Trade winds
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Position of Landmasses
Large landmasses in the Northern Hemisphere help
to dictate ocean currents and flow
Very little land in the Southern Hemisphere
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Vertical Mixing of Ocean
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Ocean Interaction with Atmosphere- ENSO

• El Niño-Southern Oscillation (ENSO)
• Def periodic large scale warming of surface
  waters of tropical eastern Pacific Ocean
• Alters ocean and atmospheric circulation patterns
• Normal conditions- westward blowing tradewinds
  keep warmest water in western Pacific
• ENSO conditions- trade winds weaken and warm
  water expands eastward to South America
• Big effect on fishing industry off South America

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El Niño

• Def. - giant puddle of heated water that
  sloshes across the Pacific Ocean
• builds in the western Pacific over a period of
  months
• This wedge of warm sea contains 20 or 30 times as
  much water as all the Great Lakes

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El Niño

• it's like an iceberg most of it is submerged,
  but part of it sticks out above the sea's
  surface, as the wedge floats in the surrounding
  ocean
• warm water is less dense than cool water
• El Niño waters are less salty than normal
  seawater
• It's always raining over an El Niño, and the
  rainwater dilutes the sea

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How??

• Some say it begins when strong west-blowing winds
  near the equator-the trade winds-push against the
  sea, and drive sun-warmed surface waters against
  Indonesia and Australia
• Others say that the wind is an effect, not a
  cause warm masses of air in the western Pacific,
  heated by already-feverish tropical waters,
  create a vacuum beneath them as they rise like
  enormous hot air balloons
• http//www.pbs.org/wgbh/nova/elnino/anatomy/origin
  s.html

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ENSO Climate Patterns
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Weather and Climate

• Weather
• The conditions in the atmosphere at a given place
  and time
• Temperature, precipitation, cloudiness, etc.
• Climate
• The average weather conditions that occur in a
  place over a period of years
• 2 most important factors temperature and
  precipitation
• Earth as many climates

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Rain Shadows

• Mountains force humid air to rise
• Air cools with altitude, clouds form and
  precipitation occurs (windward side)
• Dry air mass moves down opposite leeward side of
  mountain

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Tornadoes

• Powerful funnel of air associated with a severe
  thunderstorm
• Formation
• Mass of cool dry air collides with warm humid air
• Produces a strong updraft of spinning air under a
  cloud
• Spinning funnel becomes tornado when it descends
  from cloud
• Wind velocity up to 300mph
• Width ranges from 1m to 3.2km

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Tropical Cyclone

• Giant rotating tropical storms
• Wind gt119km per hour
• Formation
• Strong winds pick up moisture over warm surface
  waters
• Starts to spin due to Earths
• rotation
• Spin causes upward spiral
• of clouds
• Damaging on land
• High winds
• Storm surges

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Internal Planetary Processes

• Layers of the earth
• Lithosphere
• Outermost rigid rock layer composed of plates
• Asthenosphere
• Lower mantle comprised of hot soft rock
• Plate Tectonics- study of the processes by which
  the lithospheric plates move over the
  asthenosphere
• Plate Boundary- where 2 plates meet
• Common site of earthquakes and volcanoes

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Plates and Plate Boundaries
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Types of Plate Boundaries

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

• Divergent Plate Boundary-2 plates move apart

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Types of Plate Boundaries

• Transform Plate Boundary- 2 plates move
  horizontally in opposite, parallel directions

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Earthquakes

• Caused by the release of accumulated energy as
  rocks in the lithosphere suddenly shift or break
• Occur along faults
• Energy released as seismic wave
• Focus- the site where the earthquake originates
  below the surface
• Epicenter- located on the earths surface,
  directly above the focus
• Richter scale and the moment magnitude scales are
  used to measure the magnitude

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Tsunami

• Giant undersea wave caused by an earthquake,
  volcanic eruption or landslide
• Travel gt 450mph
• Tsunami wave may be 1m deep in ocean
• Becomes 30.5m high on shore
• Magnitude 9.3 earthquake in Indian Ocean
• Triggered tsunami that killed over 230,000 people
  in South Asia and Africa

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