Abstract

During many clear twilights, much of the solar sky is dominated by pastel purples. This purple light’s red component has long been ascribed to transmission through and scattering by stratospheric dust and other aerosols. Clearly the vivid purples of post-volcanic twilights are related to increased stratospheric aerosol loading. Yet our time-series measurements of purple-light spectra, combined with radiative transfer modeling and satellite soundings, indicate that background stratospheric aerosols by themselves do not redden sunlight enough to cause the purple light’s reds. Furthermore, scattering and extinction in both the troposphere and the stratosphere are needed to explain most purple lights.

© 2003 Optical Society of America

Atmospheric ozone and colors of the Antarctic twilight sky

Raymond L. Lee, Jr., Wolfgang Meyer, and Götz Hoeppe
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Measuring and modeling twilight’s Belt of Venus

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Simulating colors of clear and partly cloudy skies

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