Transcript Liquid water on its surface Oxygen atmosphere Only planet known

Earth
Liquid water on its surface
 Oxygen atmosphere
 Only planet known to support
life
 4.6 billion years old
 71% covered by H2O
 Oblate spheroid (squished
sphere)
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Compositional Zones

Crust
– 1% of Earth’s mass
– Oceanic crust
– Continental crust
Moho
– Lower boundary of the crust
– Named after Mohorovicic
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Compositional Zones

Mantle
– Layer under the crust
– More dense
– 2/3 Earth’s mass
Core
– Center of the Earth
– Composed mainly of Fe & Ni
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Structural Zones

Lithosphere
– Part of mantle and all the crust
– Rigid layer
Asthenosphere
– Below lithosphere
– Lots of heat and pressure
– Can flow
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Structural Zones

Mesosphere
– Layer of solid mantle rock
– Between asthenosphere and outer core
Core
– Outer core – dense liquid
– Inner core – dense, rigid solid
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Magnetosphere
Earth’s magnetic field
 Extends beyond the atmosphere
 Affects a region of space
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Fig. 1.11a,b
Magnetic
field lines.
Magnetic field of a bar magnet.
Magnetic field of the Earth.
Field flow lines come out of S pole, and go into N pole.
Note the error in the arrow directions at S
Magnetic field permeates the space around the Earth. It is symbolized by a bar
magnet.
Fig. 1.11c
Solar wind
Magnetosphere
Distorted magnetic
field lines
The solar wind distorts the magnetosphere into a teardrop shape, pointing away from Sun.
Earth magnetic field deflects most of the solar wind (like a shield), so that its particles do
not reach Earth surface.
The Van Allen radiation belts trap charged particles, and protect life on Earth.
The belts contain solar wind particles as well as cosmic rays which, because of their fast
speed, penetrated the outer weaker part of the Earth magnetic field, which are then trapped
by the stronger inner field.
Earth’s magnetosphere (the region inside the magnetic shield).
Solar wind interacts with Earth’s magnetic field.
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Van Allen
belts
The aurora in the Arctic. Some of the Solar wind particle, which make it
through the Van Allen belts, are channelized along the magnetic field lines to
their polar regions. These particles then interact with the gases in the upper
atmosphere, making them to glow, creating aurorae.
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Fig. 1.11d
Earth, as viewed from space. Earth atmosphere is mostly nitrogen and oxygen,
with minor amounts of Ar, CO2, and other gases. Atm. Density decreases with
altitude (we cannot breath freely at 12 km because of sparse O2 molecules)..
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Fig. 1.10
Gravity
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Force of attraction between 2 objects
 Based on mass differences and distance
between the objects
 Weight – force due to gravity (varies)
 Mass – amount of matter (constant)
Systems
Group of related objects or components that
interact to create a whole
 Earth systems transfer matter and energy
between them
 Closed system – nothing in or out
 Open system – Matter & energy can leave
or enter system
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Earth’s Four Spheres
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Makes up Earth systems
Atmosphere
1)
•
Blanket of gases that surround Earth
•
•
•
Water portion of Earth
97% salt water
3% Fresh water
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Hydrosphere
2)
Earth’s Spheres
Geosphere
3)
•
•
Mostly solid part of Earth
Crust to core
Biosphere
•
All forms of life in the other spheres
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4)
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Earth’s Cycles
2)
3)
4)
Nitrogen cycle
Carbon cycle
Phosphorus cycle
Water cycle
 Evaporation, condensation, precipitation
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1)
Ecology
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Ecosystem
– Community of organisms and their abiotic
environment
– Producers, consumers, decomposers
Carrying capacity
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Earth’s Energy Budget

Internal Sources
– Radioactive decay – especially early
– Pressure
External Sources
– Sun
 Causes motion of air & currents
 Photosynthesis
– Gravitational energy from sun & moon
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