Chapter 6
Our Living Earth
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Our Living Earth
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Cloud of gas and
dust contracts due
to gravity.
Conservation of
Angular Momentum
means it spins faster
and faster as it
contracts
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Condensation
theory:
Interstellar dust
grains help cool the
cloud, and act as
condensation nuclei
to produce flakes
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Our Solar System
The interior of
the Earth has
been
determined by
studying the
transmittal and
reflection of
Seismic Waves
within the Earth.
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Seismic waves are sound waves
generated by earthquakes. They are
compression waves and sinesoidal
waves. They reflect from and transmit
through layer interfaces with the Earth.
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The Earth has a
solid iron inner
core, a liquid iron
outer core, a
liquid rocky
mantle and a
solid rocky crust
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Can use the pattern of reflections made
during earthquakes to deduce interior
structure of Earth
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The crust of the Earth is divided into several
plates that move with respect to each other.
The movement is driven by convection
currents in the mantle. Plate movement
results in earthquakes and volcanism.
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Interactions between the plates are:
transform, sliding against each other;
divergence, separating; convergence,
coming together.
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When plates slide against each other
cracks (faults) occur and earthquakes
happen.
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The twisting Pacific plate has produced
many earthquake zones and many active
volcanoes.
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At divergent boundaries new crust is
made.
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At convergent boundaries crust is lost
by subduction (sliding under) and
crumpling (mountain building)
The Earth’s
magnetic field
appears to be
generated by
electric currents
circulating the liquid
iron core.
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The Magnetic Field
deflects the Solar
Wind around the
Earth much like a
stone in a stream
deflects water.
Charged particles that
penetrate the
boundary are trapped
in the Van Allen Belts
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The trapped hot charged particles in the Van
Allan belts are shunted toward the magnetic
poles where they interact with the air
molecules. The particles are cooled by the air
which glows as auroras.
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The Earth’s Biosphere, Oceans and
Atmosphere, come from hydrogen rich
gasses trapped inside the Earth during
creation. By far the most abundant of
the trapped gasses are methane,
ammonia, and water. The Earth is the
only planet where conditions are right
for liquid water to exist on the surface.
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Trapped gasses Outgassing
Water
Nitrogen
CO2
Carbon Dioxide
Free H
CH4
NH3
OH2
Plant Life
Oxygen
N2
O2
Water
Plant Life
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Earth’s Atmosphere
The Atmosphere
• Troposphere is where
convection takes place
– responsible for
weather
• The blue curve shows
the temperature at
each altitude
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Convection depends on warming of
ground by the Sun
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Ionosphere is ionized by solar
radiation, and is good conductor
Reflects radio waves in the AM
range, but is transparent to FM
and TV
Ozone layer is between ionosphere
and mesosphere; absorbs
ultraviolet radiation
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The Human Element
More Humans,
Industrial Revolution
Global Warming
(?)
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End Chapter 6
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