CLEVELAND — An optical phenomenon known as a 22-degree halo or "moon dog" formed around the moon Monday night.
An Instagram user shared a photo with News 5 Cleveland of the moon halo around the moon.
The "moon dog" happens when moonlight refracts off ice crystals in cirrus clouds, high up in the Earth's atmosphere, according to the National Weather Service.
The cirrus clouds contain millions of ice crystals. The halos around the moon are caused by both refraction, splitting of light, and also by reflection, or glints of light from these crystals.
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