Distributions of purple-light colors and spectra in clear twilights
Abstract
Clear civil twilights often exhibit a range of pastel purples, but the combined angular and temporal distributions of this purple light are unknown. Such distributions can now be measured by using a hyperspectral camera fitted with a fisheye lens, which gives new insights into the spread and evolution of purple-light spectra and colors during ordinary (i.e., nonvolcanic) clear twilights. Because the purple light lacks clear-cut borders, a first step is to develop a perceptually based definition of its angular extent. Surprisingly, this leads to the discovery that colorimetrically distinct purples (1) sometimes appear in both the solar and antisolar skies and (2) change in markedly different ways with sun elevation.
Fields of Study & Subjects
Color Science and Applications
Atmospheric aerosols and clouds
Scientific Research and Discoveries
Publication details
- Journal / source
- Applied Optics
- Volume
- 65
- Issue
- 9
- Pages
- C58–C58
- Publication date
- 15 January 2026
- Language
- EN