Quarter 4

• Atmosphere


  Blanket of air that surrounds the Earth and protects the planet, enabling life to exist
• Gases in the atmosphere

  • Nitrogen (78%)
  • Oxygen (21%)
  • Water vapor
  • Carbon dioxide
  • Ozone
  • Argon
  • Neon
  • Helium
  • Hydrogen
  • Dust particles
  • Chlorofluorocarbons
• 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 is given off by plants during photosynthesis
• The remaining 1% of the atmosphere is made up of trace gases
• 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 will 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 permit 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
• Layers of the atmosphere


  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Exosphere
• The temperature profile of the atmosphere is the basis for dividing the atmosphere into several layers
• Atmosphere


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


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


  • Starts at 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 as altitude increases
• Stratosphere


  • Layer of air that starts just above the troposphere and extends to about 50 km
  • Temperature increases as altitude increases due to the ozone layer
• Mesosphere


  • Layer between 50 km and 80 km above Earth's surface
  • Temperature decreases as altitude increases
  • Very cold layer with average temperature of -90°C
• Thermosphere


  • Layer between 80 km and 110 km above Earth
  • Temperature can go beyond 1000°C due to absorption of intense solar radiation
• Exosphere


  • Outermost layer of the atmosphere, more than 700 km maybe up to 10,000 km from Earth's surface
  • No clear boundary, air is very thin
• The atmosphere makes Earth "livable" by regulating solar energy and preventing it from being "too hot" or "too cold" to sustain life
• The atmosphere protects life on Earth by absorbing UV radiation from the Sun
• The atmosphere contains the oxygen we breathe
• The atmosphere is held together by Earth's gravity
• The basis for dividing the atmosphere into layers is changing temperature and composition of gases
• As hikers climb high mountains

  They need to put on thicker clothes to survive the low temperature
• The correct order of Earth's atmospheric layers from bottom to top is: Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere
• Ozone layer


  • Found in the stratosphere
  • Made up of three oxygen atoms
  • Blocks UV rays from getting to Earth
• Life on Earth would be impossible without the presence of the atmosphere
• Meteors burn up in the mesosphere due to the gases that cause friction and create heat
• Gases in the atmosphere


  • Nitrogen
  • Oxygen
• Nitrogen is the most abundant gas in the atmosphere
• Oxygen is the gas that we breathe and is necessary for our survival
• The thermosphere is the layer where auroras occur
• 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