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 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 total mass of atmosphere
  • Contains 99% of atmosphere's water
  • Where wind, clouds, and weather phenomena take place
  • Temperature decreases with altitude
• Stratosphere


  • Air flow is more stable than troposphere
  • Contains ozone layer which protects from harmful UV rays
  • Temperature increases with altitude
• Mesosphere


  • Temperature decreases with altitude
  • Coldest layer of atmosphere
  • 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 with distance from Earth
  • International Space Station and space shuttles orbit in 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
• The basis for scientists dividing the atmosphere into different layers is the change of temperature with height
• Auroras are bands of light with different colors, called aurora borealis in the north and aurora australis in the south
• Auroras can be seen in the ionosphere, which is an ion-rich region found within the thermosphere
• Latitude


  Measures the distance north or south of the equator
• Latitude lines


  Start at the equator (0 degrees latitude) and run east and west, parallel to the equator
• Equator


  A circle of latitude that divides a spheroid, such as Earth, into the Northern and Southern hemispheres
• On Earth, the Equator is an imaginary line located at 0 degrees latitude, about 40,075 km in circumference, halfway between the North and South poles
• Longitude


  Measures distance east or west of the prime meridian
• Lines of longitude


  Also called meridians, are imaginary lines that divide the Earth and run north to south from pole to pole
• Prime meridian


  The line of 0° longitude, the starting point for measuring distance both east and west around Earth
• The prime meridian is arbitrary, meaning it could be chosen to be anywhere
• The imaginary lines of latitude and longitude intersect each other, forming a grid that covers Earth
• Coordinates


  The points of latitude and longitude that can be used together to locate any point on Earth
• Latitude and longitude


  Broken into degrees, minutes, seconds and directions, starting with latitude
• An area with coordinates marked 41° 56' 54.3732" N, 87° 39' 19.2024" W would be read as 41 degrees, 56 minutes, 54.3732 seconds north; 87 degrees, 39 minutes, 19.2024 seconds west
• Tropical Zone


  The Tropic of Cancer and the Tropic of Capricorn, where countries experience a tropical climate with an annual average temperature above 18°C
• Temperate Zone


  Between the Tropic of Cancer and the Arctic Circle in the north, and between the Tropic of Capricorn and the Antarctic Circle in the south, where countries go through four seasons
• Polar Region or Frigid Zone


  Areas within the Arctic Circle and Antarctic Circle, where temperatures never go above 10°C even in summer
• Using latitude and longitude is not the only way to describe the location of a certain area, another way is by identifying the landmasses and bodies of water that are found in that area
• Natural resources


  Materials that can be used to support life and provide energy, supplied by the sun or Earth's natural processes
• Renewable resources


  Natural resources that can be replenished or regenerated naturally over time, either through natural processes or human intervention
• Non-renewable resources


  Natural resources that exist in finite quantities and cannot be replenished or regenerated within a human lifespan or over geological timescales
• Atmosphere


  A layer of gases surrounding a planet or other celestial body held in place by gravity
• Troposphere


  The layer closest to the Earth's surface, where weather occurs and contains the majority of the atmosphere's mass
• Stratosphere


  Above the troposphere, where the temperature generally increases with altitude due to the ozone layer
• Mesosphere


  Above the stratosphere, where temperatures decrease with altitude again
• Thermosphere


  Beyond the mesosphere, where temperatures increase significantly with altitude due to the absorption of solar radiation
• Exosphere


  The outermost layer of the Earth's atmosphere, where atmospheric particles escape into space