Abstract

Zenith skylight is often distinctly blue during clear civil twilights, and much of this color is due to preferential absorption at longer wavelengths by ozone’s Chappuis bands. Because stratospheric ozone is greatly depleted in the austral spring, such decreases could plausibly make Antarctic twilight colors less blue then, including at the zenith. So for several months in 2005, we took digital images of twilight zenith and antisolar skies at Antarctica’s Georg von Neumayer Station. Our colorimetric analysis of these images shows only weak correlations between ozone concentration and twilight colors. We also used a spectroradiometer at a midlatitude site to measure zenith twilight spectra and colors. At both locations, spectral extinction by aerosols seems as important as ozone absorption in explaining colors seen throughout the twilight sky.

© 2011 Optical Society of America

Tropospheric haze and colors of the clear twilight sky

Raymond L. Lee and Duncan C. Mollner
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Raymond L. Lee
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Measuring and modeling twilight’s purple light

Raymond L. Lee and Javier Hernández-Andrés
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Twilight and daytime colors of the clear sky

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Explanation of the Brightness and Color of the Sky, Particularly the Twilight Sky

E. O. Hulburt
J. Opt. Soc. Am. 43(2) 113-118 (1953)