Photometric counterpart of radiance, producing the visual sensation called brightness. Typical units are: candela m-2 (nit), candela cm-2 (stilb), foot lambert (2.426 nit). As with all photometric quantities, luminance does not refer to a specific wavelength, but applies to light emitted by a standard source (formerly a 'standard international candle', now a blackbody radiator emitting at the temperature of solidifying platinum, 2042 K). Conversion from photometric units to radiometric units (e.g. J s-1) requires convolution over wavelength of the relative spectral response of the human eye (photopic response tables).
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2199 (https://doi.org/10.1351/pac199062112167)