Transcript CH 5 Earth`s Phys Enviro

Chapter 5
Ecosystems and the Physical Environment
Overview of Chapter 5
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Biogeochemical Cycles
Solar Radiation
The Atmosphere
The Global Ocean
Weather and Climate
Internal Planetary Processes
Biogeochemical Cycles
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Matter moves between
ecosystems, biotic & abiotic
environments, and organisms
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Biogeochemical cycling
involves
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Unlike energy
Biological, geologic and
chemical interactions
Five major cycles:
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Carbon, Nitrogen, Phosphorus,
Sulfur and Water (hydrologic)
The Carbon Cycle
The Nitrogen Cycle
The Phosphorus Cycle
The Sulfur Cycle
The Water (Hydrologic) Cycle
Solar Radiation
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Sun provides energy for life, powers
biogeochemical cycles, and determines climate
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69% of incoming solar
radiation is absorbed by
atmosphere and earth
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Remainder is reflected
Albedo
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The reflectance of solar
energy off earth’s surface
Dark colors = low albedo
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Forests and ocean
Light colors = high albedo
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Ice caps
Temperature Changes with Latitude
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Solar energy does not hit earth uniformly
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Due to earth’s spherical shape and tilt
Equator (a)
High concentration
Little Reflection
High Temperature
Closer to Poles (c)
From (a) to (c)
In diagram below
Low concentration
Higher Reflection
Low Temperature
Temperature Changes with Season
Seasons
determined by
earth’s tilt
(23.5°)
Causes each
hemisphere to
tilt toward the
sun for half
the year
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Northern Hemisphere tilts towards the sun
from March 21- September 22 (warm season)
The Atmosphere
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Invisible layer of gases that
envelopes earth
Content
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21% Oxygen
78% Nitrogen
1% Argon, Carbon dioxide,
Neon and Helium
Density decreases with
distance from earth
Shields earth from high
energy radiation
Atmospheric Layers
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Troposphere (0-10km)
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Stratosphere (10-45km)
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Where weather occurs
Temperature decreases with
altitude
Temperature increases with
altitude- very stable
Ozone layer absorbs UV
Mesosphere (45-80km)
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Temperature decreases with
altitude
Atmospheric Layers
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Thermosphere (80-500km)
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Gases in thin air absorb x-rays
and short-wave UV radiation =
very hot
Source of aurora
Exosphere (500km and up)
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Outermost layer
Atmosphere continues to thin
until converges with
interplanetary space
Atmospheric Circulation
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Near Equator
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Warm air rises, cools and
splits to flow towards the
poles
~30°N&S sinks back to
surface
Air moves along surface
back towards equator
This occurs at higher
latitudes as well
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Moves heat from equator
to the poles
Surface Winds
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Large winds due in
part to pressures
caused by global
circulation of air
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Low
High
Left side of diagram
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Winds blow from
high to low pressure
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High
Right side of
diagram
Low
High
Coriolis Effect
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Earth’s rotation influences direction of wind
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Earth rotates from East to West
Deflects wind from straight-line path
Coriolis Effect
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Influence of the earth’s rotation on movement
of air and fluids
Turns them Right in the Northern Hemisphere
Turns them Left in the Southern Hemisphere
Coriolis Effect
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Visualize it as a Merry-Go-Round (see below)
Global Ocean Circulation
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Prevailing winds produce ocean currents
and generate gyres
Example: the North Atlantic Ocean
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Trade winds blow west
Westerlies blow east
Creates a clockwise gyre in the North Atlantic
Circular pattern influenced by coriolis
effect
Global Ocean Circulation
Westerlies
Trade winds
Position of Landmasses
Very little land in
the Southern
Hemisphere
Large landmasses in
the Northern
Hemisphere help to
dictate ocean
currents and flow
Vertical Mixing of Ocean
Ocean Interaction with AtmosphereENSO
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El Niño-Southern Oscillation (ENSO)
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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
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Big effect on fishing industry off South America
ENSO Climate Patterns
Weather and Climate
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Weather
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The conditions in the atmosphere at a given
place and time
Temperature, precipitation, cloudiness, etc.
Climate
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The average weather conditions that occur in a
place over a period of years
2 most important factors: temperature and
precipitation
Earth has many climates
Rain Shadows
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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
Tornadoes
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Powerful funnel of air associated with a
severe thunderstorm
Formation
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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
Hurricanes, Typhoons, Cyclones
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Giant rotating tropical storms
Wind >119km per hour
Formation
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Strong winds pick up moisture over warm surface
waters
Starts to spin due to Earth’s
rotation
Spin causes upward spiral
of clouds
Damaging on land
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High winds
Storm surges
Internal Planetary Processes
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Layers of the earth
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Lithosphere
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Asthenosphere
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Outermost rigid rock layer composed of plates
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
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Common site of earthquakes and volcanoes
Plates and Plate Boundaries
Types of Plate Boundaries
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Divergent Plate
Boundary-2 plates move
apart
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Convergent Plate Boundary2 plates move together
(may get subduction)
Types of Plate Boundaries
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Transform Plate
Boundary- 2
plates move
horizontally in
opposite,
parallel
directions
Earthquakes
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Caused by the release of accumulated
energy as rocks in the lithosphere
suddenly shift or break
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Occur along faults
Energy released as seismic wave
Focus- the site where the earthquake
originates below the surface
Epicenter- located on the earth’s surface,
directly above the focus
Richter scale and the moment magnitude
scales are used to measure the magnitude
Tsunami
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Giant undersea wave caused by an
earthquake, volcanic eruption or landslide
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Tsunami wave may be 1m deep in ocean
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Travel > 450mph
Becomes 30.5m high on shore
Magnitude 9.3 earthquake in Indian Ocean
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Triggered tsunami that killed over 230,000
people in South Asia and Africa