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