Ice fog

{
  "id": "MLC-T-MET-001359",
  "term": "Ice fog",
  "field": "Meteorology and atmospheric science",
  "definitions": [
    "A type of fog composed of tiny ice crystals suspended in the air, occurring at very low temperatures, typically below -30 degrees Celsius (-22 degrees Fahrenheit). It forms when water vapor directly sublimates into ice crystals in extremely cold, stable air. Ice fog significantly reduces visibility and is common in polar regions and high-latitude continental interiors during winter.",
    "(Also called ice-crystal fog, frozen fog, frost fog, frost flakes, air hoar, rime fog, pogonip.) A type of fog, composed of suspended particles of ice; partly ice crystals 20 to 100 micron in\ndiameter, but chiefly (especially when dense) ice particles about 12-20 micron in diameter, formed by direct freezing of supercooled water\ndroplets with little growth directly from the vapor. It occurs at very low temperatures, and usually in clear, calm weather in high latitudes.\nThe sun is usually visible and may cause halo phenomena. Ice fog is rare at temperatures warmer than -30°C, and increases in frequency with decreasing temperature until it is almost always present at air temperatures of -45°C in the vicinity of a source of water vapor. Such\nsources are the open water of fast-flowing streams or of the sea, herds of animals, volcanoes, and especially products of combustion for heating or propulsion. At temperatures warmer than -30°C, these sources can cause steam fog of liquid water droplets, which may turn into ice fog when cooled (see frost smoke). See ice-crystal haze, arctic mist."
  ],
  "synonyms": [
    "ice-crystal fog",
    "frozen fog",
    "frost fog",
    "frost flakes",
    "air hoar",
    "rime fog",
    "pogonip"
  ],
  "see_also": [
    "frost smoke",
    "ice-crystal haze",
    "arctic mist"
  ],
  "references": [
    "NWS Glossary"
  ],
  "url": "https://mlchart.com/terminology/meteorology/ice-fog/"
}