sleet science definition

Precipitation that falls to earth in the form of frozen or partially frozen raindrops, often when the temperature is near the freezing point. Sleet usually leaves the cloud in the form of snow that melts as it passes through warm layers of air during its descent. The raindrops and partially melted snowflakes then freeze in the colder layers nearer the earth before striking the ground as pellets of ice, which usually bounce. By contrast,hail  forms by the accumulation of layers of ice on the hailstone as it moves up and down in the cloud, and hailstones can become much larger than sleet pellets. The word sleet is also used informally to describe a mixture of snow, sleet, and rain.