Crepuscular rays are one of those atmospheric moments that feel bigger than the forecast. They’re among the most awe-inspiring sights in weather, slicing dramatic beams of sunlight across the sky.

Crepuscular rays are rays of sunlight that appear to radiate outward from the Sun when it is low on the horizon, most commonly at sunrise or sunset. They form when sunlight streams through gaps in clouds, terrain, or other obstructions, illuminating particles like dust, smoke, or moisture suspended in the atmosphere.

Although crepuscular rays look like distinct shafts of light spreading across the sky, the light itself is traveling in nearly parallel lines. The dramatic fan-like appearance is a result of perspective, similar to railroad tracks seeming to converge in the distance. The contrast between bright sunlit air and darker cloud shadows makes the rays visible to the human eye.

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These rays are most striking when the atmosphere contains enough particles to scatter light, such as after storms, during wildfire smoke events, or in hazy conditions. Thick clouds help block portions of the sunlight, while thinner breaks allow bright beams to shine through, creating the high contrast that defines crepuscular rays.

Summary: Crepuscular rays are beams of sunlight that appear to radiate from the Sun when it shines through gaps in clouds or terrain, creating striking shafts of light in the sky.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.