Transcript Characteristics of the atmosphere lec 22.1b

Characteristics of the Atmosphere
22.1
The Atmosphere has Five
Important Layers
• Troposphere
• Stratosphere
• Mesosphere
•Ionosphere
• Thermosphere
Troposphere
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The layer closest
to the Earth’s crust
Where the clouds,
wind & rain occur
Gets colder as
altitude increases
Inversions: warm
air sits above cold
air. Pair share: A tell B why inversions
make city smog worse.
Stratosphere
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Layer above the
troposphere
Cool & low pressure
Contains Ozone layer
O3 molecules absorb
UV radiation from sun
 Protects life
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Ozone “hole”
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Use of CFC’s have
caused a thinning
of the ozone layer
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Results: more
cancer-causing
rays hit earth
Pair share: B tell A where the
ozone is thinnest and where it
is thickest.
Ionosphere
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Between the Mesosphere & Thermosphere
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Mesosphere is the coldest layer
Thermosphere is the hottest layer
Radio waves bounce off ionosphere: reflects
them
Pair share: A tell B what therm, meso,
Aurora borealis
& sphere mean.
Aurora borealis
Auroras circle the earth’s magnetic poles
It’s caused by energy from sun exciting ions
That release photons of light
Changes over time
Early Earth’s atmosphere was toxic
 Anaerobic bacteria were the only organisms on Earth
3.5-2.5 Billion Years ago
Pair share: B tell A if people
Gases: only 1% O2 a lot of: could survive an atmosphere
H2O, CH4, H2, N2, CO, CO2 like that and why
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Change of the Earth’s Atmosphere
Over time bacteria using CO2 released O2 into the air
This made it possible for aerobic bacteria & other organisms
to thrive on Earth
 Now the Atmosphere is 21% Oxygen
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Archaea bacteria:
Aerobic bacteria:
first life forms, oxygen producers
first life forms to use oxygen
Notebook Review
1)Which layer of the
atmosphere do the
clouds reside?
2) What caused the
thinning of the ozone
layer?
3) What organisms
increased the amount
of 02 in the air?
Summary
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Main idea
Important ideas / topics
key facts
How the facts relate to the main idea