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Outline a mechanism by which part of the radiation radiated by Earth's surface is absorbed by greenhouse gasses in the atmosphere.
-Earth radiates radiation in IR spectrum
-Greenhouse gasses have energy differences corresponding to IR energies.
-IR photons absorbed by gases
Why is incoming solar radiation not affected by greenhouse gasses?
-Incoming radiation consists of photons with shorter wavelength
-these cannot be absorbed
Meaning: Degraded energy
-Energy transferred to surroundings.
-No longer available for useful work
Processes/Energy changes by which thermal energy is produced (4)
-Fission
-Nuclei have high energy
-Nuclei transfer Ke to reactor core
-Core energy transferred to coolant
Role of heat exchanger and turbine
-Heat exchanger allows energy transfer between coolant and reactor
-Coolant transfers energy to steam
-Steam allows turbine to drive dynamo
Role of moderator
-slows down neutrons
-Increases chances of initiating fission
Role of Control Rods
maintain a constant rate of fission
2 Disadvantages of using solar power to provide energy for heating water
-No power at night
-Seasonal changes
S-B law for black-body
Power emitted per unit time is proportional to temp(in K)^4
Why real average power absorbed per unit area on Earth is smaller than expected (2)
-Radiation reflected by Earth
-Some energy lost as radiation travels to earth
Why avg. Earth temp is greater than 255K (3)
-Power is reflected at longer wavelengths
-Can be absorbed by greenhouse gasses
-Some absorbed power is reflected back to Earth, increasing surface temp.
Why burning of fuels can increase surface temp of Earth
-Burning fossil fuels can release greenhouse gases like CO2
-More gases can enhance greenhouse effect
-More power absorbed from Earth and reflected back to Earth
Annual variations of solar power per unit area on earth is main due to
Angle at which the solar rays hit the surface of the Earth
Definition: Energy Density
Total energy liberated by source per kg
Definition: Specific Energy
Energy per unit volume
Why enhanced greenhouse effect can increase Earth's surface temp.
-Increased greenhouse gasses in atmosphere absorbs more IR energy and heats up
-Atmosphere radiates in all directions
-Earth surface absorbs some of the extra IR hence temperature increases.
Why is Earth's average albedo used?
Different sources absorb different intensities.
Emissivity
Emissivity of body compared to black body
How reactors produce plutonium-239
-U-238 is present
-U-238 captures neutron
Importance of plutonium-239
Pl-239 is fissionable
Note 
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