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An afterglow in Slovenian mountains, near Triglav Lakes Valley.
The afterglow is the broad high arch of whitish or rosy light, appearing occasionally in the sky, above the highest clouds in the hour of deepening twilight, ...
afterglow"1. A broad arc occasionally seen in the solar (as opposed to antisolar) sky during the darker half of civil twilight and, in principle, during nautical and astronomical twilight.
Shortly after the sun sinks below the horizon, its rays of light are reflected from the gas molecules and impurities of the atmosphere to produce afterglow. It is produced by scattering of fine particles of dust suspended in the upper atmosphere.
Subsequently, when the Sun is at least 3-4° below the horizon, and if the purple light is present, the mountains may be illuminated by a purple glow, known as the afterglow.
 See also: Twilight, Light, Weather, Clouds, Air
  
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