Alpenglow

[1] Strictly speaking, alpenglow refers to indirect sunlight reflected or diffracted by the atmosphere after sunset or before sunrise.

The term is also used informally to include direct illumination by the reddish light of the rising or setting sun, with sharply defined shadows.

Unlike the direct sunlight around sunrise or sunset, the light that causes alpenglow is reflected off airborne precipitation, ice crystals, or particulates in the lower atmosphere.

[1] After sunset, if mountains are absent, aerosols in the eastern sky can be illuminated in a similar way by the remaining scattered reddish light above the fringe of Earth's shadow.

This backscattered light produces a pinkish band opposite of the Sun's direction, called the Belt of Venus.