Science part 1

• 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 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 from ground level upward


  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Exosphere
• Basis for dividing the atmosphere into layers

  Change of temperature with height
• Troposphere


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


  • Air flow is more stable than troposphere
  • Ozone layer is found here
  • Protects from harmful UV radiation
• Mesosphere


  • Temperature decreases with height
  • Coldest layer
  • Burns up most meteors and asteroids before reaching Earth's surface
• Thermosphere


  • Closer to the sun
  • Absorbs a large amount of solar radiation
  • Temperature increases tremendously
  • International Space Station and space shuttles orbit in this layer
  • Ionosphere is found within this layer
• Exosphere


  • Merges into outer space
  • Temperature varies from very hot to very cold
  • Ideal for placing artificial satellites as there is little friction
• Auroras are bands of light with different colors, called aurora borealis in the north and aurora australis in the south
• 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
• Uses of greenhouses


  • Growing seedlings
  • Protecting flowering and ornamental plants from harsh weather conditions and insect attacks in tropical countries
• How greenhouses work


  • Transparent covering allows visible light to enter without obstruction
  • Warms the inside of the greenhouse as energy is absorbed by the plants soil and other things in the building
  • Air warmed by the heat inside is retained in the building by the roof and wall
  • Transparent covering prevents the heat from leaving by reflecting the energy back into the walls and preventing outside winds from carrying it away
• 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 different 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
• Sources of greenhouse gas emissions

  • Burning fossil fuels for electricity, heat and transportation
  • Deforestation and land clearing for agriculture
  • Degradation of soils
  • Agricultural activities
  • Waste management
  • Energy use
  • Biomass burning
  • Use of fertilizers
  • Industrial processes
  • Refrigeration
  • Use of consumer products
• 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, resulting in a reduction in biodiversity and changing climates around the globe, causing stronger typhoons and creating many health related problems
• There are a number of unique combinations of atmospheric phenomena experienced by people in all parts of the world
• Common atmospheric phenomena


  • Breezes
  • Monsoons
  • Intertropical Convergence Zone
• How air behaves when heated


  1. Air molecules move faster and spread out

  2. Makes the air less dense or light

  3. Warm air rises
• Warm air rises


  Surrounding air moves toward it to replace the rising warm air
• Wind


  Air that is moving horizontally
• Land surface heats up faster than bodies of water during the day, but land loses heat faster than bodies of water at night
• Breezes


  • Localized winds experienced by those living in coastal areas
• Types of breezes


  • Sea breeze
  • Land breeze
• Sea breeze formation


  1. Land warms up faster than bodies of water during the day

  2. Warm air above land rises

  3. Cooler air above the sea moves toward the land and replaces the warm air
• Land breeze formation


  1. Land cools faster than the sea at night

  2. Warm air over the sea rises

  3. Cooler air from the land moves toward the sea