1. A dense fog containing ice crystals that forms in clear, calm, very cold weather, especially in mountain valleys.
Usage: Regional, chiefly Western U.S.; From Shoshone pogo nipi, meaning 'cloud'; Also called rime fog or ice fog

Examples

• The pogonip rolled into the valley during the freezing night, coating everything with delicate ice crystals.
• Hikers in the Sierra Nevada are familiar with pogonip, which can reduce visibility to just a few feet.
• The pogonip formed so quickly that the windshield was covered in frost within minutes.
• Local residents warned us about the pogonip that typically occurs in winter at high elevations.
• The pogonip created a shimmering, ethereal landscape as the morning sun caught the ice crystals.