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Weather Wise: anticrepuscular rays, a meteorological optical phenomenon

Weather Wise: anticrepuscular rays, a meteorological optical phenomenon
Posted at 9:41 AM, Nov 30, 2021
and last updated 2021-11-30 11:41:04-05

HELENA — The recent weather has been weirdly warm, but what happened Sunday evening in parts of Montana seemed to defy logic.

One glance and it would appear the sun was positioned below the northeast horizon. Light seems to be emanating from behind the mountains. But it was late afternoon and the last time I checked, the sun sets to the west.

Indeed the sun was setting low in the southwest sky, but shadows and light from a mix of clouds and sun made it appear like the sun was setting in the northeast.

Crepuscular rays are beams of light that appear to converge on the sun. You've probably seen these beams of light before, but what happened Sunday night was anticrepuscular, or antisolar rays, that converge in the opposite direction and you must have your back to the sun or sunset point to see them.

The low clouds in the foreground are lit up by the sun. Shadows behind these clouds extend out toward the horizon opposite of the sun.

Anticrepuscular rays are a meteorological optical phenomenon. They are essentially parallel, but appear to converge toward the vanishing point due to a visual illusion from a linear perspective.

Big Sky Country often has a beautiful sky, doesn't it?