Crepuscular rays

(Section 3.2.3.11.4)

Sometimes, dark bluish streaks and light beams are observed radiating from the Sun across the purple light. The streaks are the shadows of clouds at or below the horizon and are called crepuscular rays. Occasionally, the beams and shadows may cross the sky, becoming visible again at the antisolar point (anticrepuscular rays). The name “crepuscular rays” is also used to indicate shadowed bands cast by clouds at any time of day. Pale blue or whitish beams are sometimes seen diverging from the Sun hidden behind cloud (usually Cumulus or Cumulonimbus). The darker streaks are the shadows of parts of the irregular cloud. Sunbeams penetrating through gaps in a layer of low cloud, and rendered visible by water or dust particles in the air, may also be referred to as crepuscular rays.