Composition and Structure of the Earth

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Composition and structure of the atmosphere

• Geography Grade 10
• NA KAMENYE

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• INTRODUCTION
• The atmosphere of the Earth is a layer of gases
  surrounding the planet Earth.
• The atmosphere protects life on Earth.
• It becomes thinner and thinner with increasing
  altitude, with no definite boundary between the
  atmosphere and outer space

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• COMPOSITION OF THE ATMOSPHERE
• The atmosphere is composed of a mixture of gases,
  solids and liquids.
• Solids? Particles of dust and dirt that float
  around in the air. Most of these particles are
  invisible to the human eye.

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• ATMOSPHERIC GASES
• (Mixture of gases, solids and liquids)
• Nitrogen - 78
• Oxygen - 21
• Water Vapor - 0 to 4
• - Used for clouds and precipitation
• Carbon dioxide 0,37
• - Keeps the Earth warm and is used by plants to
  make food
• Argon 0, 93
• Traces of neon, helium, methane, krypton, xenon,
  hydrogen and ozone

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Structure of the Atmosphere The atmosphere has
five (5) layers
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• 1. Troposphere
• The troposphere is the layer directly above the
  earths surface.
• It extends up from surface for 12 km. the upper
  boundary of the layer is the tropopause.
• It is warmed by the earths long-wave radiation,
  and processes like conduction and convection.
• The temperature decreases with increasing
  altitude at average rate of 6,4c/1000 m. this is
  called the environmental/normal lapse rate.
• All weather processes take place in this layer.
• Air pressure falls with height.

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• 2. Stratosphere
• The stratosphere layer extends in altitude from
  12-50 km. the upper boundary of the layer is the
  stratopause.
• The ozone layer is situated between 15-35 km
  above the ground and is called the ozonosphere.
  ozone absorbs incoming ultraviolet radiation,
  which may be harmful to humans, other animals and
  plants.
• The stratosphere is characterised by an increase
  in temperature caused by a concentration of
  ozone.
• Stratosphere is the layer of the atmosphere where
  planes usually fly. Most of the jet aircraft fly
  in the lower layer of the stratosphere, to avoid
  any turbulence.
• It acts as protective layer against incoming
  meteorites.

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• What is ozone?
• Ozone is a gaseous layer in the stratosphere that
  protects the earth from harmful ultraviolet (UV)
  radiation.
• It is a molecule made up of three oxygen atoms,
  often referenced as O3.

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• 3. MESOSPHERE
• The mesosphere layer extends from 50-80 km.
• It receives meteoric dust, which forms nuclei.
• Noctilucent clouds form from ice crystals.
• Temperature falls rapidly, with lowest
  temperatures of -90c. ice crystals form around
  nuclei.
• It is the coldest layer
• Strongest winds are recorded
• Meteors burn up due to friction

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• 4. THERMOSPHERE
• The thermosphere is the uppermost layer of the
  atmosphere, from 80-480 km. uppermost boundary is
  the thermopause.
• There is a rapid increase in temperature with
  increase in height, to 1500c.
• Solar radiation is absorbed by atomic oxygen.

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• 5. EXOSPHERE
• The exosphere is the outermost layer of the
  atmosphere.
• The temperature in the exosphere goes up with
  altitude.
• Satellites orbit earth in the exosphere.

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