2.1 - Radiation principles

The Sun is the main source of energy in the earth-atmosphere system, irradiating electromagnetic energy in a wide range of wavelengths. According to Planck’s law, all bodies with temperature above 0K emit electromagnetic radiation. A black body at Temperature T emits radiation according to equation 2.1:


Bλ (Wm-3) = energy emitted at a given wavelength λ (m);
c1 and c2 are constants (3.74x10-16 Wm2 and 1.44x10-12 mK, respectively).

The spectral distribution of the emitted radiation of a body (B as a function of λ) can be obtained by applying the Planck function at a given temperature T and considering a range of possible wavelengths.