Layers of the Atmosphere

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Layers of the Atmosphere
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The 4 Layers of the Atmosphere

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Ionosphere?
• http//earthguide.ucsd.edu/earthguide/diagrams/atm
  osphere/index.html

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Gravity and the Atmosphere

• The troposphere and stratosphere contain 99 of
  the atmosphere's mass.
• This is because these are the layers closest to
  the Earth.
• Therefore, the Earths gravity has the greatest
  affect on the gases in these layers.

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Troposphere

• The troposphere is the lowest and the densest
  layer.
• This is the layer where all weather occurs.
• Why

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How Weather Works

• As Earth's surface absorbs radiation from the
  Sun, it warms the lower level of the troposphere.
• The warmed air becomes less dense and rises
  through the cooler air above it.
• This happens by convection.

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Troposphere Convection

• Because temperature and pressure drop with
  increasing altitude in this layer, convection
  creates a lot of turbulence.

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Troposphere and Weather

• Weather is caused by this rising of heat from the
  Earths surface which will cause two important
  processes
• Air will flow as the pressure from the heat below
  and the cold above causes it to churn.
• Water will evaporate from the Earths surface and
  either fall again as rain or snow as it rises and
  cools.

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Stratosphere

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Stratosphere

• In the lower stratosphere the temperature is
  almost -60C which is about -76F.
• Temperature rises steadily to about 0C at an
  altitude of about 50 km above Earths surface.
• So why does the temperature increase with
  altitude?

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Ultraviolet Radiation

• Air in the stratosphere is heated from above by
  absorption of ultraviolet radiation by ozone.

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Stratosphere Ozone

• Ozone absorbs ultraviolet radiation from the sun
  and converts it into heat.
• The warmer air forms a blanket above the cold air
  so the temperatures in the stratosphere remain
  very stable.
• http//www.teachersdomain.org/resources/ess05/sci/
  ess/watcyc/ozonehole/index.html
• http//info-pollution.com/common.htm
• http//www.teachersdomain.org/resources/ess05/sci/
  ess/watcyc/antarctica/index.html

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Mesosphere

• Located above the stratosphere
• Extends to an altitude of 80 km
• The air pressure is very low in this layer.
• So there are very few molecules to absorb any
  solar radiation.
• What do you think will happen as we rise in
  altitude?

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Mesosphere Temperature

• Because there is little absorption of solar
  radiation, the temperature decreases with
  increasing height.
• The average temperature is -90C
• (-130F)
• This is the coldest temperature in the
  atmosphere.

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Thermosphere

• The outermost layer of the atmosphere, the
  thermosphere, is the first to receive the Sun's
  radiation.
• It is strongly affected by solar energy.
• Nitrogen and Oxygen molecules absorb solar
  radiation (ultraviolet).
• What do you think happens to the temperature?

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Thermosphere

• The temperature of each molecule rises to greater
  than 1,000C or 1,832F.
• However, the molecules are spread so far apart
  that if you could travel through the thermosphere
  it would feel cool.
• http//www.teachersdomain.org/resources/ess05/sci/
  ess/watcyc/vertical/index.html

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Ionosphere

• The ionosphere is not a separate atmospheric
  layer.
• It makes up less than 1 of the atmosphere.
• It is a layer of gases in the thermosphere and
  mesosphere that are ionized by solar radiation.
• Solar radiation causes the atoms of gas molecules
  to lose electrons producing ions and free
  electrons.
• H Li Na K

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Auroras

• Interactions between solar radiation and the
  ionosphere cause auroras.
• http//www.teachersdomain.org/resources/ess05/sci/
  ess/eiu/auroras/index.html

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Exosphere

• Region of the thermosphere where Earths
  atmosphere blends into the almost complete vacuum
  of space
• Extends for thousands of kilometers above the
  ionosphere.