Radiance is a term in radiometry. It is defined as:
L = d 2 Φ d A d Ω c o s θ {\displaystyle L={\frac {d^{2}\Phi }{dAd\Omega cos\theta }}}
Typical units are [ W m 2 s r ] {\displaystyle [{\frac {W}{m^{2}sr}}]} where "sr" means steradians.
![{\displaystyle [{\frac {W}{m^{2}sr}}]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/2a89b42dc7acdd163a52a0924a4125e4c8318fdd)
where "sr" means steradians.