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When you look up at the night sky, you may sometimes see a faint, ring-shaped glow around the full moon or a bright moon. This is an atmospheric optical phenomenon known as a lunar halo or moon halo ✨.

This phenomenon is caused by cirrostratus clouds located about 5 to 13 kilometers above the ground ☁️. These clouds contain hexagonal ice crystals, and when moonlight passes through them, the light is refracted and reflected, forming a circular ring of light in our line of sight 🔭.

Since ancient times, people have said, “When there’s a halo around the moon, the weather will worsen,” and in fact, the appearance of a lunar halo often signals an approaching change in weather 🌧️. This is because the cirrostratus clouds indicate that a low-pressure system or a weather front is drawing near.

Next time there’s a clear night, take a moment to observe the moon closely 🌌. You just might witness the beautiful and fleeting artwork of the atmosphere — the lunar halo 🔮.