Accretion (meteorology) Accretion (meteorology) Accretion is defined as the gradual collection of something over time. In meteorology or atmospheric science it is the process of accumulation of frozen water as precipitation over time as it descends through the atmosphere, in particular when an ice crystal or snowflake hits a supercooled liquid droplet, which then freeze together, increasing the size of the water particle. The collection of these particles eventually forms snow or hail in clouds and depending on lower atmosphere temperatures may become rain, sleet, or graupel. Accretion is the basis for cloud formation and can also be seen as water accumulates
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