ISO/TC 211 Multi-Lingual Glossary of Terms (MLGT)

blackbody radiance

Ibb,v

physical radiance of an absorber determined by applying Planck's function (either in wavelength space or in terms of frequencies) to absorber temperature, ${\displaystyle T_{\text{w}}}$ , as shown in the following formula (in frequency space): ${\displaystyle I_{\text{bb,v}}=\frac{2\text{h}{v}^3}{c^2}\frac{1}{e^{\frac{\text{h}v}{\text{k}{T}_{\text{w}}}}-1}}$ where ${\displaystyle T_{\text{w}}}$ is the temperature of the absorber; ${\displaystyle \text{h}}$ is the Plank’s constant (${\displaystyle 6.62607\times {10}^{-34}\text{J}\cdot \text{s}}$ ); ${\displaystyle v}$ is the frequency in Hz; ${\displaystyle \text{c}}$ is the velocity of light (${\displaystyle 2.997925\times {10}^8\text{m}/\text{s}}$ ); ${\displaystyle \text{k}}$ is the Boltzmann’s constant (${\displaystyle 1.38064852\times {10}^{-23}\text{J}/\text{K}}$ ); ${\displaystyle \text{e}}$ is the base of natural logarithm.

[SOURCE: ISO/TS 19159-4:2022, 3.10]