science

• Earth is the only planet that is known to sustain life in our solar system
• One of the factors that make our planet habitable is its atmosphere
• Atmosphere


  The blanket or envelope of gases surrounding the earth
• The atmosphere keeps us warm, gives us oxygen to breathe, and is where weather happens
• The atmosphere also keeps the overall temperature of the earth fairly steady, especially between night and day
• Gases in the earth's atmosphere

  • 78% nitrogen
  • 21% oxygen
  • 1% other trace gases including carbon dioxide, inert gases, hydrogen, methane, ozone
• Layers of the atmosphere

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


  • Lowest layer
  • Makes up 75% of the total mass of the atmosphere
  • Contains 99% of the atmosphere's water
  • Where wind, clouds, and weather phenomena take place
  • Air is constantly moving, causing turbulence for aircraft
• Stratosphere


  • Air flow is more stable than in the troposphere
  • Ozone layer is found here, which protects from harmful UV radiation
• Mesosphere


  • Temperature decreases with altitude
  • Coldest layer of the atmosphere
  • Burns up most meteors and asteroids before they reach the earth's surface
• Thermosphere


  • Closer to the sun, absorbs a large amount of solar radiation
  • Temperature increases tremendously with distance from the earth
  • International Space Station and space shuttles orbit in this layer
• Ionosphere


  • Ion-rich region found within the thermosphere
  • Auroras are visible in this layer
• Exosphere


  • Last layer, merges into outer space
  • Temperature varies from very hot to very cold
  • Ideal for placing artificial satellites as there is little friction
• The earth's atmosphere is divided into different layers and is made of different types of gases
• More than three quarters of earth's atmosphere is made up of nitrogen while one film is oxygen
• The remaining one percent is a mixture of carbon dioxide water vapor ozone and other trace gases
• These gases not only produce important weather features such as cloud and rain but also have considerable influence on the overall climate of the earth through the greenhouse effect and global warming
• Greenhouse


  A structure with walls and roofs made chiefly of a transparent material such as plastic or glass, useful in growing seedlings when this winter or spring before planting them in the open field when the weather is warmer
• Greenhouses


  • Allow sunlight to enter but prevent heat from escaping
  • The transparent covering allows visible light to enter without obstruction and warms the inside of the greenhouse as energy is absorbed by the plants soil and other things in the building
  • The air warmed by the heat inside is retained in the building by the roof and wall
  • The transparent covering prevents the heat from leaving by reflecting the energy back into the walls and preventing outside winds from carrying it away
• The earth's atmosphere is compared to a greenhouse


  The trace gases in the atmosphere have a similar effect on the sun's rays as the glass in a greenhouse
• Greenhouse gases


  Gases that trap the sun's heat in the atmosphere, examples are carbon dioxide, methane, ozone, water vapor, and nitrous oxide
• Greenhouse effect


  The process where greenhouse gases trap the heat in the atmosphere
• The greenhouse effect is a natural process that warms the earth's surface and makes the earth much warmer than it would be without an atmosphere
• The greenhouse effect plays an important role in our survival
• Due to human activities, more greenhouse gases are emitted into the earth's atmosphere which results in an enhanced greenhouse effect
• Enhanced greenhouse effect


  More heat is trapped and reflected back to the earth's surface due to the higher presence of greenhouse gases
• Global warming


  The current rise in the average temperature of earth's air and oceans
• The largest source of greenhouse gas emissions particularly carbon dioxide from human activities is burning fossil fuels for electricity, heat and transportation
• Carbon dioxide is also emitted into the atmosphere through deforestation, land clearing for agriculture and degradation of soils
• Agricultural activities, waste management, energy use and biomass burning contribute to greenhouse gas emissions
• Fertilizers used by many farmers is the primary source of nitrous oxide emissions
• Industrial processes, refrigeration and the use of a variety of consumer products contribute to the emissions of chlorinated gases
• Many of these greenhouse gases can cause earth's atmosphere to trap more and more heat, increase air temperature and cause global warming
• Global warming is feared to melt polar ice caps and cause flooding to low-lying areas that will result in a reduction in biodiversity
• Global warming is already changing climates around the globe causing stronger typhoons and creating many health related problems
• Breezes


  Winds that are evident near bodies of water, localized winds experienced by those living in coastal areas
• Sea breeze


  • Occurs during the day, land warms up faster than bodies of water, warm air on land rises, cooler air from sea moves towards land to replace warm air
• Land breeze


  • Occurs during the night, land cools faster than sea, warm air over sea rises, cooler air from land moves towards sea
• Monsoons


  Wind systems that involve bigger masses of air that move horizontally, usually bring abundant rainfall
• Northeast monsoon


  • High pressure in China and Siberia, low pressure in south Indian Ocean/Australia, wind comes from northeast, dry and cold