III. Energy

1. energy - capacity to do work
2. heat energy - the movement of atoms and molecules in a substance (vibration and displacement)
3. temperature - the average speed (energy) of atoms and molecules in a substance
4. heat - energy transferred from one substance to another because of a difference in temperature

1. conduction - energy transfer between touching objects
2. movement
   • convection - vertical motion redistributes energy
   • advection - lateral motion redistributes energy
3. radiation - electromagnetic waves carry energy

1. Emission of electromagnetic radiation
• wavelength varies: longer wavelengths carry less energy than short (Fig. 2-11, 2-12)
(short) x-rays >>>> UV >>>> visible >>>>>IR>>>>> radio waves (long)
• everything emits e-m radiation (range of wavelengths)
• amount of energy radiated increases with increasing temperature
• wavelength decreases with increasing temperature (high T emits short wavelength)(fig. 2-12)
• sun is hot and emits much shortwave radiation
• Earth is cool and emits less longwave radiation
2. Effects - travel path of e-m rays in atmosphere (Fig 2-12)
1. absorbed
2. transmitted
3. redirected (Fig. 2-14)
• reflected - albedo (Table 2-3)
• scattered
  • diffused light
  • blue sky and red sunset (Fig 2-16)
3. Absorption of electromagnetic radiation
   everything absorbs e-m radiation
1. blackbodies - absorb all the radiation that strikes it and emits as much as possible for its temperature
2. selective absorbers - only absorb certain wavelengths, while allowing others to pass through
• they generally emit at the same wavelengths that they absorb
• ozone - O3 - absorbs short wavelength UV radiation (hot sun)
• greenhouse gasses - (H₂0,CO₂, N₂O, CH₄...) absorb long wavelength IR radiation (cool Earth)
4. atmospheric radiation (fig. 2-18; 2-19)
1. greenhouse effect
2. ozone depletion