Transcript Ch 5 wo cycles

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
• forests, ocean, asphalt
Light colors = high albedo
• ice caps, desert sands,
clouds
4 way Solar Radiation makes life
on earth possible
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warming the planet to a habitable temp
powers the biogeochemical cycles
allows producers to photosynthesize and
feed other living organisms
stored in fuels – wood, oil, coal, nat’l gas
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 caused by
earth’s tilt (23.5°)
o Causes each
hemisphere to tilt
toward the sun for
half the year
o Hem. Tilted toward
sun receives more
direct solar
radiation & warmer
temps.
o Northern Hemisphere tilts towards the sun
from March 21- September 22 (warm season)
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Temperature Changes with Season
Seasons
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Hem. tilted toward sun rec. more direct solar radiation
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Northern Hemisphere
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Summer Solstice – Earth tilts toward sun
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Autumnal Equinox – Earth along side sun
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First day of Fall
Sept 21 or 22
Winter Solstice – Earth tilts away from sun
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First day of Summer
June 21 or 22
First day of Winter
Dec 21 or 22
Vernal Equinox – Earth along side sun
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First day of Spring
Mar 21 or 22
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 we live
where weather occurs
temp decreases with altitude
temp increases with altitude
very stable
Ozone layer absorbs UV
Mesosphere (45-80km)
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temp decreases with altitude
down to -138oC, -216oF
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, 1000oC, 1832oF
source of aurora
Exosphere (500km and up)
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outermost layer
no distinct boundary between it
and outer space
just continues to thin
Atmospheric Circulation
Moves heat from equator to the poles
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Warm air rises, cools and
splits to flow towards
the poles
~30° N & S sinks back to
surface
air hits surface and
splits to flow N & S
air warms and rises again
at ~60° N & S
air sinks at poles
Heat is transferred throughout
atmosphere in 3 ways
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Radiation
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Conduction
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heat energy transferred in the form of rays or waves
land and water absorb heat
heat energy transferred through direct contact
air above land is in direct contact with land
*heat is always transferred from warmer to cooler
Convection
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heat energy transferred through the flow of a fluid
(liquid or gas)
warm air rises because less dense
cool air sinks because more dense
Surface Winds
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Large winds due in part
to high and low
pressures caused by
global circulation of air
Winds blow from high
to low pressure
Little wind at latitudes
of 0, 30, 60 & 90
because air rising or
sinking
High
Low
High
Low
High
Low
High
Prevailing Winds
Winds are named for the direction FROM WHICH
they move
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Polar Easterlies
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Prevailing Westerlies
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blow from East to West
Between 90o and 60o N or S
blow from West to East
Between 30o and 60o N or S
Trade Winds
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blow from East to West
Between 0o and 30o N or S
Which of these are “our“ winds?
Prevailing Westerlies
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 (these are our winds)
Creates a clockwise gyre in the North Atlantic
Circular pattern influenced by coriolis
effect
Coriolis Effect
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Earth’s rotation influences direction of wind
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Coriolis Effect
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Earth rotates from East to West
Deflects wind from straight-line path
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
chalk board globe
Coriolis Effect
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Visualize it as a Merry-Go-Round (see below)
Global Ocean Circulation
Westerlies
Trade winds
Position of Landmasses
Large landmasses in the
Northern Hemisphere
dictate ocean currents
and flow
Very little land in the
Southern Hemisphere
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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conditions in the atmosphere at a given place
and time
temperature, precipitation, cloudiness, etc.
Climate
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average weather conditions that occur in a
place over a period of years
2 most important factors: temperature and
precipitation
Earth as 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 / Tropical Cyclone
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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
Damage 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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Crust (oceanic & continental), mantle, core
Lithosphere – crust + upper mantle
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Asthenosphere – lower mantle
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rigid rock layer
tectonic plates
molten
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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3 types
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convergent – plates moving toward each other
• volcanoes & EQ
divergent - plates moving away from each other
• mid-ocean ridges, volcanic activity
transform – plates sliding/grinding past each
• earthquakes
Mantle Convection
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Causes plate movement
Convection currents in asthenosphere move beneath
lithosphere and drag plates along
Plates and Plate Boundaries
Types of Plate Boundaries
Convergent Plate Boundary: plates move toward
each other
• oceanic-continental crust =
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subduction of oceanic plate
(as shown)
• Examples:
• Andes Mountains
• Cascade Range in
Oregon and Washington
state – Mt. Saint Helen’s
continental-continental =
no subduction; HUGE
mountain ranges
Examples:
Himalayas, Apalachian
Mountains
Types of Plate Boundaries
Divergent Plate Boundary:
plates move away from one
another
Examples:
Mid-Atlantic Ridge
Types of Plate Boundaries
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Transform Plate
Boundary: plates
move horizontally
in opposite,
parallel directions
Examples:
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San Andres Fault,
CA
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- where 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