Sponge: List the six layers of the Earth.

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Sponge List the six layers of the Earth.
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AtmosphereA mixture of gases N2
78 O2 21 Ar 0.9 CO2 0.03
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Water vapor in the atmosphere varies from 0.1 to
3.
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What makes Earth unique is Oxygen.The
presence of water and carbon dioxide is also
important.
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The atmosphere provides oxygen, protects the
Earth from harsh solar and cosmic radiation,
keeps most meteoroids from becoming meteorites,
and keeps the Earths surface warm.
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The atmosphere is like a protective blanket for
the Earth.
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The atmosphere is relatively small, half below 5
km, 99 below 30 km.
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Density and pressure decrease steadily with
height.
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Layers of atmosphereTroposphere - below 15
kmStratosphere - 15 to 40-50 kmMesosphere - 50
to 90 kmThermosphere - above 90 kmExosphere -
above 250 km
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The troposphere is the area where convection
occurs.This rising of warm air and sinking
of cooler air is powered by the surface heat of
the Earth.
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These convection currents are responsible for
all the weather on Earth.
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Temperature decreases with altitude in the
troposphere.
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The top of the troposphere is the tropopause.
Above this, in the stratosphere, the air is
still.
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Within the stratosphere, the ozone layer is
found.
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In the ozone layer the temperature increases as
solar UV radiation is absorbed by O2, O3
(ozone), and N2.
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This absorption of UV radiation protects the
Earth from its effects.
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The ozone layer stretches into the mesosphere,
although the term stratosphere is often used to
refer to both the stratosphere and the mesosphere.
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In the thermosphere, the temperature increases
with altitude because the high-energy part of the
Suns spectrum splits molecules into atoms and
atoms into ions.
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This ionization of the atmosphere is significant
above about 100 km. This electrically conductive
part of the atmosphere is called the ionosphere.
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This ionosphere is part of the thermosphere and
can actually reflect certain radio wavelengths.
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The surface of the Earth absorbs much energy from
the Sun and reradiates it. Most of this energy
escapes into space, but infrared radiation is
partially blocked by the carbon dioxide and water
vapor in the atmosphere.
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This partial blocking of solar radiation is
called the greenhouse effect.
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Warmed air rises and is replaced by air that has
been cooled in the upper atmosphere. This
produces a circulation pattern called a
convection cell.
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This rising and falling air affects atmospheric
heating and also produces surface winds.
Passenger aircraft tend to fly above these
disturbances, in the lower stratosphere.
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The magnetosphere is the region around the Earth
influenced by the Earths magnetic field. This
field is similar to that of a bar magnet roughly
aligned with the spin axis of the Earth.
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It was detected by satellites launched in the
late 1950s. It contains two doughnut-shaped
zones of high energy particles (one about 3000
and the other 20 000 km above the Earths
surface), called the Van Allen Belts. The
radiation here is lethal.
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The magnetic field is believed to be caused by
rotating, conducting material (molten iron and
nickel) flowing in the Earths outer core. This
is called dynamo theory.
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The high energy particles in the Van Allen Belts
are collected from the solar wind and are trapped
because they are charged particles (primarily
protons and electrons).
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These charged particles often escape near the
poles, where the magnetic field intersects the
atmosphere. They rip apart air particles,
creating spectacular lights called the aurora.
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In the north, these lights are called the aurora
borealis (northern lights). In the south, they
are called the aurora australis (southern
lights).
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Aurorae as seen from ISS
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Perseid meteor to the left
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The Aurora Australis (from space)
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Earth isnt the only planet to have aurorae. The
next three pictures are of aurorae on Saturn.
Notice the strange hexagonal shape on the last
image.
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The magnetic field is distorted by the solar
wind. On the daytime side of the Earth, the
magnetosphere is compressed.
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The boundary between the magnetosphere and the
solar wind is called the magnetopause and is
found about 10 Earth radii from the Earths
surface.
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On the side opposite the Sun, the field lines
are extended, often reaching beyond the Moons
orbit. As a result the magnetosphere is
teardrop-shaped.
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The magnetosphere screens out much destructive
radiation from the solar winds.
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In the year 2000, we were at the peak of solar
activity and the highest solar winds. If you fly
75,000 air miles on passenger jets, it is like
being exposed to 20 X-ray procedures.
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