Precipitation types the preceding adjective "freezing", becoming known as freezing rain or freezing drizzle. Frozen forms of precipitation include snow, ice needles, sleet, hail, and graupel. Their respective intensities are classified either by rate of fall, or by visibility restriction. Precipitation falls in many forms, or phases. They can be subdivided into: The parenthesized letters are the METAR codes for each phenomenon. Precipitation occurs when local air becomes saturated with water vapor, and can no longer maintain the level of water vapor in gaseous form. This occurs when less dense moist air cools, usually when an airmass rises through the atmosphere. However,
2005 United Kingdom snow events North Yorkshire received 20 cm of snow over high ground, whilst the snow caused huge tailbacks on the A1 between Alnwick and Berwick. The snow showers petered later on the 29th as outbreaks of rain, sleet and hill snow moved into western areas. On Friday 30 December, a band of heavy rain pushed eastwards, with heavy snow on the leading edge. This brought several hours of snow followed by rain, where 20 cm fell in some parts of Yorkshire, with snowdrifts of 1 metre reported. The snow caused hundreds of drivers to be stranded on the A1079 during the late