Module 3

• Earth is surrounded by a blanket of air called the atmosphere, and this protects the planet and enables life to exist
• Composition of air


  • Nitrogen (78%)
  • Oxygen (21%)
  • Other gases (1%)
• Nitrogen is the most abundant gas and is essential for all living things to grow
• Oxygen is necessary for humans and animals for survival, and this gas is given off by the plants as one of the by-products during photosynthesis
• The remaining 1% is made up of other gases such as water vapor, carbon dioxide, ozone, argon, neon, helium, hydrogen, dust particles, and chlorofluorocarbons
• If the percentage of nitrogen and oxygen in air were reversed

  Oxidation will proceed at a much faster rate—we will age sooner, fruits will ripen faster, rusting and burning go on at a much faster rate
• If the concentration of carbon dioxide and nitrogen were reversed


  Life would not exist on Earth
• The 0.03% concentration of carbon dioxide is sufficient to keep Earth warm and permits life to exist
• Increasing the concentration of carbon dioxide to 78%

  Will greatly increase Earth's temperature
• The atmosphere has several layers that differ in altitude, temperature, and other characteristics
• Meteorology is the branch of science which deals with the study of the atmosphere and its corresponding weather patterns
• People who study the atmosphere are called meteorologists
• Troposphere


  • Starts at the Earth's surface and extends 8 km to 14.5 km high
  • About 75% of the gases in the atmosphere can be found in this layer
  • Temperature decreases with altitude
• Stratosphere


  • Temperature increases with altitude
• Mesosphere


  • Temperature decreases with altitude
• Thermosphere


  • Temperature increases with altitude
• Exosphere


  • Outermost layer of the atmosphere
• The temperature profile of the atmosphere is the basis for dividing the atmosphere into several layers

  
• Each layer of the atmosphere has its own distinct characteristics
• Atmosphere


  A mixture of gases and particles that surround a planet, held by gravity
• Layers of the atmosphere

  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Exosphere
• Troposphere


  The layer that starts at the Earth's surface and extends 8 km to 14.5 km high, where most weather changes and patterns happen
• Stratosphere


  The layer that starts just above the troposphere and extends to about 50 km, where the ozone layer is found
• Mesosphere


  The layer between 50 km and 80 km above the Earth's surface, which is characterized as a very cold layer with an average temperature of -90°C
• Thermosphere


  The layer between 80 km and 110 km above the Earth, where the temperature can go beyond 1000°C due to the absorption of intense solar radiation
• Exosphere


  The outermost layer of the atmosphere, more than 700 km, maybe up to 10,000 km from the surface of Earth with no clear boundary
• The atmosphere protects us from dangerous radiation from the Sun through the ozone layer
• The atmosphere contains the oxygen we breathe
• The atmosphere makes Earth "livable" by regulating solar energy or the energy coming from the sun which drives all life processes on Earth
• Because of the atmosphere, Earth is not "too hot" nor "too cold" to sustain life
• As altitude increases

  Temperature decreases in the troposphere
• As altitude increases


  Temperature increases in the stratosphere
• As altitude increases


  Temperature decreases in the mesosphere
• As altitude increases


  Temperature increases in the thermosphere
• The atmosphere is held together by Earth's gravity
• Altitude


  The vertical elevation of an object above a surface (such as sea level or land) of a planet or natural satellite
• Troposphere


  The layer where most of the weather occurs
• Ozone


  A molecule made up of three oxygen atoms
• The greenhouse effect is the warming of a planet due to trapped radiation
• Carbon dioxide causes global warming