Download Earth`s “Spheres” - The University of Texas at Dallas

Earth’s “Spheres”
Atmosphere
Hydrosphere
Lithosphere
=
The Earth
System
Biosphere
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Some Fundamental Principles
The
universe is regular, predictable and
quantifiable
Earth’s
surface is constantly changing
Everything
All
on Earth operates in cycles
life forms evolved by natural selection
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Key Factors in Earth’s Evolution
After
partial melting, it remains hot inside
due to energy from radioactive elements.
The
distance from the Sun and Earth’s
natural “greenhouse” allow liquid water to be
present.
Development
of a Biosphere.
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A Force: Gravity The Great Leveler
Related
to product of masses (m x m) and
inversely to distance squared

Weight = mass x g (i.e., weight ≈ mass)
At
Earth’s surface, all motion is due to
gravity
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An Energy - Heat
“Transfer
of energy resulting from
temperature differences”
Bodies
at same T are in thermal equilibrium
Sources
Internal
of heat: internal and external
- radioactive decay; cooling of
interior
External
- sun (also source of light energy)
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Sources of Interior Heat
Cooling
Decay
of Earth from its original molten state
of radioactive elements
Major
One
ones are U, Th, K, Rb
element is converted to another
(Ex. U => Pb)
An
Same
energetic particle and heat are released
principle as the atomic bomb
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Transfer of Heat
Convection
- transfer by flow of fluid or
molten material
Conduction
Radiation
- transfer through a solid
- transfer through air, liquid or
vacuum
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Heat and Density
Most objects expand when heated
Decreases density (less mass per unit volume)
Density changes cause fluids to move
Less dense rises; denser sinks
Hot air rises; cold air sinks
Heat also causes phase changes (water to vapor)
Salt content also affects density

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Gravity and Density
All
movements via density changes are
affected by gravity
Objects
becoming cooler (i.e., denser) than
their surroundings will sink
Objects
becoming warmer (i.e., less dense)
than surroundings will rise
Phase
changes are density changes and
are affected by gravity
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Natural Energy Sources
Fusion Energy
External
Energy
Sun
HEAT AND LIGHT
Biol.
Prod.
Currents
Waves
Wind
Destroys
mountains
Evap.
Builds
mountains
HEAT
Internal
Energy
Earth's Interior
Fission Energy
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Earth’s Layers
How did Earth become density stratified?
• Young Earth was probably homogeneous
• Heat and gravitational pressure caused Earth to partially
melt
• Gravity then pulled iron and other heavy elements into the
center of Earth, heating the planet further
• Lighter minerals migrated to Earth’s surface and formed
the crust
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The Formation Of Earth
Density stratification
results in an inner and
outer core, a mantle
and crust.
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Where did Water Come From?
• Earth’s lost its first atmosphere
• Gases, including water vapor, released by the process of
outgassing, replaced the first atmosphere.
• Water vapor in the atmosphere condensed into clouds.
• After millions of years, the clouds cooled enough for water
droplets to form.
• Hot rain fell and boiled back into the clouds.
• Eventually, the surface cooled enough for water to collect
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in basins.
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The Early Atmosphere
The early atmosphere was very different from the atmosphere today.
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How old is the Earth, and how do we
know it?
Rocks
can be dated by measuring the rate
of radioactive decay of certain elements.
The
oldest objects found on Earth are
meteorites that are about 4.6 b.y.
Lunar
rocks are also this age.
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A Timeline Of Earth’s History
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Figure 1.6
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Global
Positioning
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Figure 1.8
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Figure 1.15
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Figure 1.16
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Figure 1.10
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30
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Figure 1.19
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Figure 1.21
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Figure 1.22
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