How Snow Makes Sleet And Freezing Rain
Snow may create a winter wonderland, but it also creates some of the nastier winter weather like sleet and freezing rain.
A small variation in temperature determines if precipitation falls as snow, sleet or freezing rain. Sleet is a form of precipitation that falls somewhere between snow and rain. It occurs when snowflakes partially melt then refreeze into ice pellets before reaching the ground. Sleet usually bounces when it hits an object on the ground, but it can accumulate like snow causing hazardous road conditions.
Snowflakes are also necessary to make freezing rain. Freezing rain forms when falling snowflakes melt. As the melted snow reaches the ground it travels through a thin layer of freezing air, which supercools the drop near the ground. Because the drops are supercooled they instantly refreeze upon contact with anything below freezing, creating an icy glaze on things like the ground, trees, power lines and roads, creating hazardous driving conditions.