Dear Tom,
What is the difference between sleet, snow and ice pellets?
Clifford Poust, Chicago
Dear Clifford,
Snow and sleet are different forms of solid (versus liquid) precipitation. Snow consists of delicate, featherlike ice crystals, usually matted together to form the much larger snowflakes that we are all familiar with.
Snow forms in clouds when water vapor condenses (technically, the process is deposition) at sub-freezing temperatures directly into ice crystals.
Sleet consists of small, hard, irregularly shaped pieces of ice, and they bounce when they strike the ground. Sleet forms when raindrops or partially melted snowflakes fall through sub-freezing air and then freeze before they reach the ground. In standard international terminology, sleet is known as "ice pellets."
