Earth

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Earths Atmosphere
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How our atmosphere evolved

• I. The early atmosphere did not support life. It
  contained deadly gases such as Methane and
  Ammonia. There was very little Oxygen.
• II. Over time, gases were added to the atmosphere
  by volcanic eruptions, and as a result of
  chemical reactions due to sunlight.

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How our atmosphere evolved cont.

• III. The OZONE LAYER formed as a result of the
  chemical reactions. Ozone is made of three
  oxygen atoms bonded together. It blocks out
  ultraviolet radiation from the sun.
• IV. The formation of the ozone layer allowed
  MICRO-ORGANISMS such as Blue-Green Algae to
  appear on earth. They take in carbon dioxide and
  release oxygen, so the amount of OXYGEN in the
  atmosphere steadily increased.

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How our atmosphere evolved continued

• V. Stromatolites were some of the early organisms
  that used Photosynthesis to convert CO2 into
  Oxygen. They still exist today and have survived
  5 mass extinctions!

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Todays atmosphere
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Layers of the Atmosphere
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Basis for Layers

• Layers are based on TEMPERATURE CHANGE within the
  layer.
• As you move up through the troposphere,
  temperature decreases.
• As you move up through stratosphere, temperature
  increases.
• As you move up through the mesosphere,
  temperature decreases
• As you move up through the thermosphere,
  temperature increases.

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Characteristics of layers

• Troposphere Contains Convection Currents created
  by the suns heat which cause most of our weather
• Stratosphere Contains the Ozone Layer.
• prevents some ultraviolet radiation UV light from
  reaching Earths surface, also where airplanes
  fly.
• Mesosphere Meteors burn up when they hit this
  layer.
• Thermosphere Divided into Ionosphere and
  Exosphere. Satellites Radio waves travel in
  this layer. This is the hottest layer

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Thermosphere has 2 parts

• Ionosphere Lower Thermosphere. Contains
  electrically charged particles due to absorption
  of ultraviolet radiation and X-rays that are
  given off by the sun. Aurora Borealis can be
  seen in this layer. Radio waves travel easily
  in this layer.
• Exosphere Upper thermosphere. Air is extremely
  thin. Satellites travel here because there is
  very little friction with air.

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Aurora Borealis ? A glow in the night sky
produced in the upper atmosphere by ionized
particles from the solar wind interacting with
Earths magnetic field.
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Transfer of Heat Heat can move in three ways

• 1- Conduction Heat is transferred through direct
  contact.
• 2- Convection Heat is transferred by a hot fluid
  (gas or liquid) circulating or moving.
• 3- Radiation Heat is transferred by
  electromagnetic waves.

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What is Convection?

• ? Density differences in temperatures cause heat
  to rise and cool to sink, this applies to gasses
  and liquids
• Examples
• Heated water becomes less dense and rises,
  Boiling water
• Hot air expands and is less dense hot air balloon

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Warmth as your hands absorb the radiation coming
from the fire.
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Heat moves into our atmosphere through SOLAR
RADIATION (Insolation)
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Heat moves throughout (within) our atmosphere in
CONVECTION CURRENTS
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Heat Transfer Quiz Identify the type of Heat
Transfer
C
B
A
A Radiation
B Convection
C Conduction
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