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Energy

  • How is Energy transported around the planet
    • Atmospheric Circulation
    • Oceanic Circulation
  • Energy is the capacity to do work
  • Energy can be neither created nor destroyed
  • Can be converted from one form to another
    • Kinetic Energy (energy of motion)
    • Potential Energy
      • Positional energy
      • Energy in chemical bonds
      • Energy in electromagnetic radiation (light)
      • Energy in matter itself
  • The first law of thermodynamics: total amount of energy in the universe is constant
    • But systems within the universe can gain or lose energy
    • When a vase hits the floor
      • Sound waves
      • Motions of pieces
      • Heat
  • The second law of thermodynamics: every energy transformation increases disorder (entropy)
    • Energy tends to go from more usable to less usable forms
    • Least stable energy form is heat
    • Heat is energy contained in random motion of molecules

Types of Energy

  • Electromagnetic radiation: light
    • Travels at the speed of light (186,000 miles/s)
    • Amount of energy determined by the wave length
    • Electromagnetic spectrum: Full range of wave lengths
  • Heat: kinetic energy of moving molecules
    • Temperature: average kinetic energy of a collection of molecules
    • Transferred by:
      • Conduction: direct transfer of heat
      • Convection: warm (less dense) regions of gas or liquid rise
      • Radiation: matter loses heat by radiation, producing electromagnetic energy
      • Latent heat transfer: heat transfer associated with phase transition (melting, freezing, evaporation, condensation)
  • Chemical Energy: potential energy associated with the formation or breakage of bonds between atoms
    • Photosynthesis converts electromagnetic radiation (sunlight into chemical energy (sugar))
  • Nuclear Energy: the energy contained in an atoms nucleus
    • $E = mc^2$ ($Energy = Mass \times SpeedOfLight^2$)
    • Nuclear fission: splitting the nucleus
  • Most of the earths energy is derived from electromagnetic radiation emitted by the sun
  • Radiates energy back into space (primarily as infrared radiation)

Atmospheric Circulation

  • Why is the earth so warm and other parts are cold?
    • The sun rays strike at different parts of the earth at different angles
    • Sunlight reaching tropical regions arrives nearly perpendicular to the surface.
    • Sunlight reaching polar regions arrives at a oblique angle, which spreads over a larger area
  • The seasons are caused by the sun hitting the earth at non consistent angles
  • Earth is tilted 23.5 degrees
  • In polar regions heat radiation is greater than solar radiation
  • Short wave Radiation:
    • Solar
  • Long wave Radiation:
    • Heat
  • Density: mass / volume
    • usually constant for solids
    • can change significantly for fluids (and gasses)
    • Altered by changes in temperature and pressure
    • increased temp = decreased density
    • increased pressure = increased density
    • Less dense fluids want to rise above more dense ones, take for example hot air balloons
  • The spinning planet force is known as the Coriolis Effect
  • The ocean retains more heat than land
    • Oceans are typically warmer at night than land
    • During the day it is typically cooler
    • Sea breezes flow from sea to land during the day
  • Storms
    • Areas of surface heating will lead to rising air
    • Rising air must be replaced by air from the surrounding areas
    • The area of rising air is known as a low pressure zone
    • Coriolis causes the moving air to spiral
    • Rising air cools, causing humid air to condense
    • Condensing air leads to cloud formation and potentially precipitation
  • Hurricanes (tropical cyclones): rotating mass of warm humid air
    • Condensation of humid air in the hurricanes leads to the release of latent energy
    • Converted to wind energy
    • Requiring hot oceanic water

Ocean Circulation

  • Two important forms of ocean circulation
    • Surface currents: (wind driven circulation)
      • Rapid
      • High variable
    • Deepwater flow: (thermohaline circulation)
      • Overturning ocean
      • Long-term transport (1000 yr)
      • driven by dense sinking water
  • Wind driven circulation
    • Wind transfers energy through friction
    • Coriolis effect turns water to the right
    • Leads to gyres
    • Gyre: large system of rotating ocean current
  • Water along the eastern boundaries of the ocean are typically colder because of costal upwelling
    • Brings cold, deep, nutrient rich water to the surface
  • Thermohaline cycle:
    • Slow circulation of the deep ocean
    • Driven by density
    • Dense water sinks into polar regions
    • replaced by upwelling in other regions of the world
    • Redistributes heat around the globe
    • Large part of why Europe isnt covered in ice