Radiative transfer is the physical phenomenon of energy transfer in the form of electromagnetic radiation. The propagation of radiation through a medium is affected by absorption, emission, and scattering processes. The equation of radiative transfer describes these interactions mathematically. Equations of radiative transfer have application in wide variety of subjects including optics, astrophysics, atmospheric science, and remote sensing. Analytic solutions to the radiative transfer equation (RTE) exist for simple cases but for more realistic media with complex multiple scattering effects numerical methods are required.
The present article is largely focused on the condition of radiative equilibrium.[1] [2]
Contents
1 Definitions
2 The equation of radiative transfer
3 Solutions to the equation of radiative transfer
3.1 Local thermodynamic equilibrium
3.2 The Eddington approximation
4 See also
5 References
6 Further reading
Definitions
The fundamental quantity which describes a field of radiation is called spectral radiance in radiometric terms (in other fields it is often called specific intensity). For a very small area element in the radiation field, there can be electromagnetic radiation passing in both senses in every spatial direction through it. In radiometric terms, the passage can be completely characterized by the amount of energy radiated in each of the two senses in each spatial direction, per unit time, per unit area of surface of sourcing passage, per unit solid angle of reception nctions of temperature and density only, and are related by: