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8.2 Thermal energy transfer :explode: (The Greenhouse Effect (Greenhouse…

- - - - absolute temperature (T) in K
      - surface area (A)
      - surface characteristics, represented by a constant 'e' (emissivity)
- - - - Earth's Albedo is 0.30, which means 30% of the Sun’s rays that reach the ground are reflected back into the atmosphere.
      - The ocean has an albedo as low as 0.06 and snow has one of 0.90
  - - - if e=1, object is:
        
        in an equilibrium with its surroundings (emission=absorbtion)
        
        radiating energy that is characteristic of its temperature
        
        depending on temperature the power emitted as radiation by an object with thermal energy is not distributed uniformly across all wavelengths
        
        at smaller object temperatures the overall radiative power emitted is smaller and its wavelength distribution is shifted towards increasingly larger wavelengths.
        
        graph: the instensity of emitted radiation at different wavelengths for a black body at various temperature
        
        emitted power of a black body
        
        P(black body)=σA(blackbody)*T^4(black body)
        
        σ=5.6710^(-8) Wm^(-2)*K^(-4)
        
        a black body
        
        black body radiation
        
        occupies a continuous spectrum of wavelengths with a sharp limit to short wavelengths (usually in the ultraviolet region)
        
        always includes wavelengths larger than those of visible light
        
        has an asymmetric intensity variation with wavelength that peaks toward smaller wavelengths
        
        has an intensity peak at a wavelength that can be predicted by the object temperature
        
        Wien's displacement law states that for a black body, the wavelength of peak radiation emission λmax is related to temperature (T) of a black body by:
        
        (λmax/m)= (2.9010^(-3) mK) / (T/K)
        
        black body glows red at λmax = 0.7 μm at 4500 K
        
        black body glows blue at λmax = 0.4 μm at 7000 K