The Earth and its Subsystems

• System


  Set of interconnected components that interact to form a unified whole
• Types of System


  • Open
  • Closed
  • Isolated
• Open System


  • Allows energy and mass to pass across the system boundary
  • Example: Ocean
• Closed System


  • Allows energy but not the mass to pass across the system boundary
  • Example: Earth
• Isolated System


  • Neither mass nor energy is allowed to pass through the system boundary
  • Example: Closed Thermos Bottle
• Subsystems of the Earth

  • Biosphere
  • Hydrosphere
  • Atmosphere
  • Geosphere
• Biosphere


  Living components of the planet, "Life zone" including all organisms and organic matter yet to be decomposed
• Biosphere


  • Biotic: living parts
  • Abiotic: nonliving parts (air, water, temperature)
  • Allows energy transfer from one group to another and allows certain animals to consume them
  • Structured into a hierarchy known as the food chain
• Food Chain


  Sequence of transfers of matter and energy in form of food from organism to another in a linear network of links in a food web
• Food Web


  Composed of several interconnected food chains that involve more organisms
• Energy Pyramid


  Demonstrates the transfer of energy from one organism to another along the food chain
• Biosphere interaction with other subsystems

  • Atmosphere: Life processes may involve chemical reactions which may emit or extract gases (e.g. photosynthesis)
  • Hydrosphere: Evaporation of water from leaf surfaces (transpiration) which transfers water into the atmosphere
  • Geosphere: Connected through soils, plant activity is essential for the mechanical and chemical breakdown of rocks
• Hydrosphere


  Dynamic mass of water that is continuously on the move, encompasses the waters of the earth including ground, surface, and glacier waters
• 70% of the planet is covered in water in the form of the ocean, 3% is fresh water, ⅔ is in the form of ice and the remaining ⅓ is present in streams, lakes, and groundwater
• Cryosphere


  The frozen part, includes ice sheets, ice shelves, caps, glaciers, permafrost, etc.
• Properties of water that make it essential for life


  • Could be in many forms
  • Neutral pH
  • Good conductor of heat and electricity
  • High specific heat
  • Universal solvent
• Hydrosphere interaction with other subsystems

  • Atmosphere: Transferred between bio and hydrosphere by evaporation, energy exchange
  • Biosphere: Transport of nutrients and waste production in organisms
  • Geosphere: Primary agent for breakdown of rocks (weathering), form loose rock fragments and sculpts the surface
• Atmosphere


  The thin gaseous layer that envelopes a planet or celestial body
• Atmosphere is composed of 78% nitrogen, 21% oxygen, 0.9% argon, and a trace amount of other gases
• Importance of the Atmosphere

  • Protection (planetary debris, radiation)
  • Security blanket (heat regulation)
  • Weather and Water
  • Source of gases essential for life
• Layers of the Atmosphere

  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
• Troposphere


  • Lowest layer or closest to earth, 10 to 20km above sea level, thinnest layer, Weather occurs here, contains almost all of the mass, An increase in altitude means a decrease in temperature, Tropopause: boundary between troposphere and stratosphere, abrupt change in lapse rate
• Stratosphere


  • Second layer, 50 km above sea level, 20 to 25 km thick, increase in altitude, increase in temperature as the ozone layer absorbs the heat, the Ozone layer is located here, planes and jets fly in this layer as the air is thinner and there is less friction
• Mesosphere


  • Middle layer, 50-80km above sea level, altitude increases, temperature decreases, coldest layer, temperatures reach 90 degrees Celcius because there are few air molecules so it doesn't absorb heat from the sun, protects the Earth's surface from meteoroids (shooting stars)
• Thermosphere


  • Outermost layer, 80km above sea level, thickest layer, altitude increase, temperature increase, hottest layer, temperatures reach 1,800 degrees celsius, has two layers: Ionosphere and Exosphere
• Ionosphere


  The lowest layer of the thermosphere, 80-400 km above sea level, molecules become electrically charged particles due to the energy from the sun, these particles are useful for communication as they bounce radio waves, aurora borealis (north), aurora australis (south)
• Atmosphere interaction with other subsystems

  • Hydrosphere: Gases readily exchange with those dissolve in water bodies
  • Biosphere: Supplies oxygen and co2 that is necessary for life processes
  • Geosphere: Gases react with water to produce weak acids that aid in water breakdown
• Geosphere


  Contains all the solid land of the planet's crust, the semi-solid second layer, and the liquid land near the center
• Layers of the Earth (Chemical Composition)

  • Crust
  • Mantle
  • Core
• Crust


  • Silica, oxygen, sodium, the rocky outermost layer of the planet, composed of a great variety of igneous, metamorphic, and sedimentary rocks, made up of granitic rocks with lighter colors
• Mantle


  • Magnesium, Oxygen, Iron-magnesium silicates, middle layer composed of dense rocks largely made up of mineral olivine, less dense than the core but denser than the crust
• Core


  • Iron, Nickel, innermost part, believed to be metallic
• Layers of the Earth (Physical Composition)

  • Litosphere
  • Asthenosphere
  • Mesosphere
  • Outer Core
  • Inner Core
• Lithosphere


  • Solid top layer, crust and the upper mantle, floats on top of the asthenosphere
• Asthenosphere


  • A thin layer of the mantle under the lithosphere, composed of hot, semi-solid material, not liquid but acts like a plastic, more fluid than the rest of the mantle, low viscosity
• Mesosphere


  • The rest of the mantle, solid and rigid compared to the asthenosphere because the temperature is not high enough to overcome the pressure, highly viscous
• Outer Core


  • Liquid low viscosity, cause of the earth's magnetic field
• Inner Core


  • Solid due to pressure
• Two Kinds of Earth's Crust

  • Oceanic Crust
  • Continental Crust
• Oceanic Crust


  • Covers the ocean's basins, thinner than continental crust, composed of a basaltic layer, denser, less buoyant, geologically young