A faint band, purple in color, seen over much of the solar sky during a clear twilight. The purple light exists when sun elevation −2° < h₀ < −6°. Its azimuthal width is ∼40°–80°, and its vertical or elevation-angle width is ∼10°–15°. Maximum luminance occurs at h₀ ∼ −4°, and the area of purple light steadily descends toward the solar point during evening twilight. At h₀ ∼ −7°, the bright segment replaces the purple light.