Glowing Peaks imaged in Glacier National Park by Peg Zenko (Tangent Photos). Image ©Peg Zenko, shown with permission.
Immediately after sunset high mountains continue to glow with a red-orange and increasingly shadowless light.
They are first lit by the sun still shining at higher altitudes and then by the light of the glowing western sky itself, the '"Twilight Arch". Eventually the peaks take on a purple hue and are bright against the darkening sky.