The Atmosphere

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Atmosphere A thin envelope of gases that
surrounds the earth. Has 4 main layers
Troposphere Stratosphere Mesosphere
Thermosphere (Ionosphere)
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Troposphere Layer closest to the earth
75 of earths air is found here Extends
from earths surface up to 17Km Consists
mainly of N2 (78) O2 (21) Other gases
(Ar, CO2, etc.) make up 1 Water vapor is
also found here (.01-5.0) The higher into
this layer the air pressure temp. (except at
very top temp. gets warmer). The top of
this layer Tropopause
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Troposphere cont.. Air in this layer
turbulent (constantly rising falling.
Causes earths weather This is the most
dense atmospheric layer The troposphere
together with the tropopause are known as the
lower atmosphere.
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Stratosphere The second layer from the
earths surface Extends from 17Km to 48Km
above earth This layer is very dry and less
dense The temperature increases in this area
due to the absorption of UV radiation. This
layer contains the Ozone Layer (shield) The
air in this layer is very calm The top of
this layer is known as the Stratopause
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Mesosphere The 3rd layer from the earths
surface Extends from 48Km 80Km above
earth Since there is less ozone, the temp.
starts to decrease. Temperature reaches its
coldest (-900C) at top of this layer Top of
this layer Mesopause Most meteors that
enter earths atmosphere burn up in this layer.
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Thermosphere (Ionosphere) This is the 4th
layer of the atmosphere From 80Km 320Km
above earth Very susceptible to solar
radiation Temperature can fluctuate greatly
Can reach temp. of 15000C Reflects radio
waves ( allows for communication) Area where
aurora (northern lights) takes place
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2 Major atmospheric Processes Ozone Layer
(Shield) Greenhouse Effect Both play an
important role in the earths climate and
biodiversity. Both occur naturally Both
are being negatively influenced by humans.
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Ozone Layer (Shield) O3 Forms when O2
reacts with lightning UV Keeps 95 of
suns harmful rays from reaching the earths
surface. Harmful to earths organisms
If lost, earth would not be able to sustain life
Holes (thin spots caused by industrial
pollution) have been discovered over the poles.
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Greenhouse Effect A rise in temp. in the
earths atmosphere due to the trapping of heat by
atmospheric gases. Without it, earth would
be about 600F colder Increased gases (due to
pollution) can cause less heat to escape Can
lead to Global Warming
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Global Warming Problems caused due to
GW Melting glaciers, early snowmelt and
severe droughts could cause water
shortages in the American West. Rising sea
levels could lead to coastal flooding on the
Eastern seaboard the Gulf of Mexico.
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Global Warming Cont... Warmer sea surface
temperatures could fuel more intense
hurricanes Forests, farms and cities could
face troublesome new pests and more
mosquito-borne diseases. Disruption of
habitats could drive many plant and
animal species to extinction.