Types of Wintry Precipitation
Lately on Delmarva, our Storm Team has mentioned the possibility of wintry precipitation with the recent storms this month. The 1st thought that comes to mind is usually snow, but 2 other types need to be considered as well, which are sleet and freezing rain. This blog explains the differences of these 3 types of wintry precipitation, along with rain.
All precipitation across the world starts as snow as it falls from the clouds in the atmosphere, but the interaction of how much warm air or not determines, if it will continue that way or change into something else. Snow occurs when the temperature is below freezing (<32°) from the base of the cloud to the ground. Snow can fall dry or wet. Dry snow occurs when temperatures are well below freezing, which is powdery. Wet snow happens when it just above freezing aloft where the snow can partially melt and fall with more moisture and water content. Wet snow is ideal for making snowballs and snowmen. Snow however can also occur above freezing when the air aloft is cold, but a shallow layer near the ground is warm, but without the opportunity for the snow to melt.
Sleet happens when the snow encounters a shallow layer of warm air which partially melts but then refreezes as it falls through deep layer of cold air above the surface. They fall as frozen raindrops when making contact on the surface, creating a tapping sound. This collection of ice pellets however, can make vehicles skid on the road, especially on bridges.
Freezing rain occurs when a deep layer of warm air melts the snowflake into a raindrop but encounters a shallow layer of cold air just above the surface. Since the cold layer is thin, it does not refreeze above the surface but when making impact on the surface. This will create a glaze of ice over roads, trees, sidewalks and power lines; which can lead to destruction due to its weight on objects, but also dangerous driving & walking conditions. Lastly we have rain, where the snowflake melts into a raindrop as it encounters above freezing temperatures all the way down to the surface.
Since all types of precipitation have their hazards, make sure to stay safe and also tune in to our Storm Team to get the latest winter weather information.