Commuting: What happens in snow?

snow /snō/ noun 1. atmospheric water vapor frozen into ice crystals and falling in light white flakes or lying on the ground as a white layer. "we were trudging through deep snow"

Snow falls in several forms:

• Snowflakes are clusters of ice crystals that fall from a cloud.
• Snow pellets, or graupel, are opaque ice particles in the atmosphere. They form as ice crystals fall through supercooled cloud droplets, which are below freezing but remain a liquid. The cloud droplets then freeze to the crystals, forming a lumpy mass. Graupel tends to be soft and crumbly.
• Sleet is composed of drops of rain or drizzle that freeze into ice as they fall, and is sometimes called a wintery mix of rain and snow. These small, translucent balls of ice are usually smaller than 0.76 centimeters (0.30 inches) in diameter. Official weather observations may list sleet as ice pellets. In some parts of the United States, the term sleet can refer to a mixture of ice pellets and freezing rain.
• One form of precipitation, hail, while frozen, is not considered snow. Hail tends to be larger than sleet, and is usually generated during thunderstorms, which happen more often in spring and summer than in winter. Hailstones form when upward moving air, or updrafts, in a thunderstorm prevent pieces of graupel from falling. Drops of supercooled water hit the graupel and freeze to it, causing the graupel to grow. When the balls of ice become too heavy for the updrafts to continue supporting them, they fall as hailstones.