A long-standing assumption about the clear sky is that its colors and luminances are distributed symmetrically about the principal plane. As useful as this approximation is, our digital-image analyses show that clear-sky color and luminance routinely depart perceptibly from exact symmetry. These analyses reconfirm our earlier measurements with narrow field-of-view spectroradiometers [J. Opt. Soc. Am. A 18, 1325 (2001)], and they do so with much higher temporal and angular resolution across the entire sky dome.
© 2003 Optical Society of America
Original Manuscript: January 8, 2002
Revised Manuscript: March 25, 2002
Published: January 20, 2003
Javier Hernández-Andrés, Raymond L. Lee, and Javier Romero, "Color and luminance asymmetries in the clear sky," Appl. Opt. 42, 458-464 (2003)