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
Hail hailstones, described as between the size of bumble bees and ping pong balls, were accompanied by rain and high winds. The hail fell in only the one area, leaving the surrounding area untouched. It fell for one and a half hours between 10 p.m. and 11:30 p.m. A meteorologist for the National Weather Service in Boulder said, "It's a very interesting phenomenon. We saw the storm stall. It produced copious amounts of hail in one small area. It's a meteorological thing." Tractors used to clear the area filled more than 30 dump-truck loads of hail. Research focused on four individual