This study presents the results given by 51 series of 77 spectral directional measurements of sky radiance, taken under various sky conditions, in Lyon, France (lat: 45 degrees 78 N, long: 4 degrees 93 E, alt: 170 m). The analysis focuses on the relationship between the luminance of any point in the sky and its correlated colour temperature. It is shown that the spatial and spectral distribution of light on the sky vault can be obtained by combining: (1) a sky luminance distribution model -the ASRC-CIE Perez model was used here as an example, (2) a relationship between luminance and correlated colour temperature - a model was developed through this work, and (3) a model to derive the spectrum of daylight from its correlated colour temperature - the CIE method was used in this study.