How Do Freezing Rain and Sleet Form?
Winter brings the chance for more than just rain. But how do meteorologists determine whether it will be snow, sleet or freezing rain? Winter weather is some of the most challenging to forecast as many different things can change the precipitation type from one winter storm to the next or even within the same winter storm.
Freezing Rain happens when raindrops fall in liquid form and immediately freeze as they hit a cold surface. This can occur as rain or snow falls through a deep layer of warm air aloft. This turns the snow to rain or keeps the rain in liquid form. As the rain falls, it passes through a very cold, but shallow layer of cold air at the surface and once it hits the ground, trees, cars or other items it freezes.
Sleet forms when a raindrop or a snowflake that partially melts as it falls through a thin layer of warm air aloft , turns back into ice as it falls through a deep layer of cold air at the surface. Sleet is usually tiny clear ice pellets that bounce when they hit the ground.
Snow begins in the atmosphere as water condenses into a tiny droplet. As more and more water vapor condenses onto its surface, the droplet grows. Cold air then freezes this water into an ice crystal. As long as the air temperature remains at or below freezing the snow will reach the ground.
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