Pogonip is a rare type of fog that forms in very cold weather, usually below freezing, when tiny supercooled water droplets in the air condense and coat everything they touch in a layer of frost.

The name comes from the Shoshone word for “white death.” The icy mist can also irritate your throat and lungs if inhaled too deeply. Pogonip is most often seen in mountain valleys of the western United States, where frigid temperatures and still air allow this eerie, sparkling fog to develop.

Its appearance is striking — trees, fences and power lines can quickly become encased in a delicate layer of white rime, giving the landscape a glittering, frozen look. But despite its beauty, pogonip can be treacherous: It reduces visibility, adds dangerous weight to structures and poses health risks to people and animals caught outdoors in it.

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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.