A vocabulary of landscape — a landscape of words
1469 entries
pogonip
Pogonip is dense freezing fog that forms in a valley in cold still weather and coats every surface with white ice crystals. It occurs in the Great Basin and the mountain West when an inversion traps cold air in a basin, and it can sit for days, with the sun visible overhead and the valley below in white murk. Everything in it grows a coat of rime on the windward side.
Etymology
The word came into English from Shoshone and entered western American usage in the nineteenth century. It is one of the few weather terms English took from a Great Basin language and it survives as the standard local word in Nevada and eastern California, appearing in forecasts and in place names.
Notes
The ice-crystal coating is properly rime rather than hoar frost, since it is deposited from supercooled droplets striking a surface rather than from vapor. Pogonip and the inversions that produce it are the reason Great Basin valleys can be far colder than the ranges above them, and a drive up out of one on a January morning can gain twenty degrees in a few hundred feet.