Download Atmospheric Heating

Atmospheric Heating
What You Will Learn
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Describe what happens to solar
energy that reaches Earth.
Summarfte the processes of
radiation, thermal conduction, and
convection.
Explain the relationship between
the greenhouse effect and global
warming.
Vocabulaty
radiation
thermal conduction
convection
global warming
greenhouse effect
Reading Organizer As you read
this section, make a table comparing
raa1atlo1,
and convection.
londuction,
You are lying in a park. Your eyes are closed, and
feel the warmth of the sun on your face. You may
done this before, but have you ever stopped to :
that it takes a little more than eight minutes for
energy that warms your {ace to travel {rom a star #
149,000,000 km away?
Energy in the Atmosphere
In the scenario above, your face was warmed by energy r:
rE,
the sun. Earth and its atmosphere are also warmed by ene:r
from the sun. In this section, you will find out what happ-_:i
to solar energy as it enters the atmosphere.
Radiation: Energy Transfer by Waves
The Earth receives energy from the sun by radiation. Radiatin
the transfer of energy as electromagnetic waves. Although :
sun radiates a huge amount of energy, Earth receives :
about two-billionths of this energy. But this small fractic:energy is enough to drive the weather cycle and make E-habitable. Figure r shows what happens to solar €fr€rg, i rr
it enters the atmosphere.
F,igure I E7ergy from the sun is obsorbed by
the otmosphere, lond, ond woter and is choiged
into thermol energy.
About 25o/o is scattered and reflected
by clouds and air.
About 20o/o is absorbed by
ozone, clouds, and atmospheric gases.
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About 50o/o is absorbed
by Earth's surface.
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About 5olo is reflected
by Earth's surface.
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Possible Causes of Tectonic Plate Motion
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You have learned that plate tectonics is the theory that ::.lithosphere is divided into tectonic plates that move around ::
top of the asthenosphere. What causes the motion of tecto:-:
plates? Remember that the solid rock of the asthenosph=:=
flows very slowly. This movement occurs because of chan.:
in density within the asthenosphere. These density chan.:
are caused by the outward flow of thermal energy from d.--:
within the Earth. When rock is heated, it expands, becor:-:
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the rock gets near the surface, the rock cools, becomes rn:::
dense, and tends to sink. Figure I shows three possible caus*'
of tectonic plate motion.
What causes changes in density in the
asthenosphere?
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Mid-ocean ridge
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Push At mid-ocean ridges, the
oceanic lithosphere is higher than it is
where it sinks into the asthenosphere.
Because of ridge push, the oceanic
lithosphere slides downhill under the
force of gravity.
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Oceanic lithosphere
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Pull
Because oceanic lithosphe=
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edge of the tectonic plate that conta
Convection Hot rock from deep within
the Earth rises, but cooler rock near the
surface sinks. Convection causes the
oceanic lithosphere to move sideways
and away from the mid-ocean ridge.
oceanic Iithosphere sinks and pulls trt
rest of the tectonic plate with it in a
process called slob pull.
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