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  2. Absorptance - Wikipedia

    en.wikipedia.org/wiki/Absorptance

    Hemispherical absorptance: A — Radiant flux absorbed by a surface, divided by that received by that surface. This should not be confused with "absorbance". Spectral hemispherical absorptance: A ν A λ — Spectral flux absorbed by a surface, divided by that received by that surface. This should not be confused with "spectral absorbance ...

  3. Attenuation coefficient - Wikipedia

    en.wikipedia.org/wiki/Attenuation_coefficient

    The absorption coefficient of a volume, denoted μ a, and the scattering coefficient of a volume, denoted μ s, are defined the same way as the attenuation coefficient. [ 6 ] The attenuation coefficient of a volume is the sum of absorption coefficient and scattering coefficients: [ 6 ]

  4. Emissivity - Wikipedia

    en.wikipedia.org/wiki/Emissivity

    Hemispherical absorptance: A — Radiant flux absorbed by a surface, divided by that received by that surface. This should not be confused with "absorbance". Spectral hemispherical absorptance: A ν A λ — Spectral flux absorbed by a surface, divided by that received by that surface. This should not be confused with "spectral absorbance ...

  5. Schwarzschild's equation for radiative transfer - Wikipedia

    en.wikipedia.org/wiki/Schwarzschild's_equation...

    The absorption coefficient is fundamentally the product of a quantity of absorbers per unit volume, [cm −3], times an efficiency of absorption (area/absorber, [cm 2]). Several sources [2] [12] [3] replace nσ λ with k λ r, where k λ is the absorption coefficient per unit density and r is the density of the gas.

  6. Stefan–Boltzmann law - Wikipedia

    en.wikipedia.org/wiki/Stefan–Boltzmann_law

    The Earth has an albedo of 0.3, meaning that 30% of the solar radiation that hits the planet gets scattered back into space without absorption. The effect of albedo on temperature can be approximated by assuming that the energy absorbed is multiplied by 0.7, but that the planet still radiates as a black body (the latter by definition of ...

  7. Kirchhoff's law of thermal radiation - Wikipedia

    en.wikipedia.org/wiki/Kirchhoff's_law_of_thermal...

    Next, suppose we have a material that violates Kirchhoff's law when integrated, such that the total coefficient of absorption is not equal to the coefficient of emission at a certain , then if the material at temperature is placed into a Hohlraum at temperature , it would spontaneously emit more than it absorbs, or conversely, thus ...

  8. Transmittance - Wikipedia

    en.wikipedia.org/wiki/Transmittance

    Transmittance of ruby in optical and near-IR spectra. Note the two broad blue and green absorption bands and one narrow absorption band on the wavelength of 694 nm, which is the wavelength of the ruby laser. In optical physics, transmittance of the surface of a material is its effectiveness in transmitting radiant energy.

  9. Reflectance - Wikipedia

    en.wikipedia.org/wiki/Reflectance

    The spectral hemispherical reflectance in frequency and spectral hemispherical reflectance in wavelength of a surface, denoted R ν and R λ respectively, are defined as [1] =,,, =,,, where Φ e, ν r is the spectral radiant flux in frequency reflected by that surface;