Wet Wintry Weather

Dec. 8, 2014- A cold front pushed in wet, wintry weather that caused some school delays and slippery travel for us in the Stateline. A combination of sleet, freezing rain, snow, fog, and rain showers were seen at different parts of the morning.

The radar image from    this morning.  A combination of rain (green), frozen precipitation (pink), and snow (blue) can be seen.

The radar image from 7 AM this morning. A combination of rain (green), frozen precipitation (pink), and snow (blue) can be seen.

With the variety of winter weather seen today, I thought I’d put together a refresher on terms and how they form, because I’m sure this won’t be the last time this winter that we’ll be talking about these types of precipitation!

The amount of cold air in the atmosphere helps determine the precipitation type.  The deeper the cold air, the more likely the precipitation falls frozen.

The amount of cold air in the atmosphere helps determine the precipitation type.

This graphic shows a cross-section of the atmosphere.  The red color is warm (above freezing) air, and the cold is below freezing (cold) air. The deeper the column of below freezing air in the atmosphere, the more likely precipitation will fall frozen.

RAIN- since this precipitation type falls non-frozen, the air is usually above freezing from the surface to the cloud.

FREEZING RAIN- in this case, there is a layer of below freezing air right at the surface. Rain is able to fall unfrozen until it reaches the surface; there, it can freeze onto anything untreated and below freezing.  This is where we get the glaze of ice that covers all surfaces.

SLEET- with sleet, the column of below freezing air is deeper, rain is able to freeze below it gets to the ground. We get our pellets of ice in this instance.  Despite falling as frozen pieces of ice, sleet can still lead to a slippery layer on the roads and sidewalks.

SNOW- snow, of course, needs a deep layer of below freezing air to get the snow flakes to form.

Thankfully, we do not have to deal with any kind of wintry precipitation for the rest of the week, but keep these terms and how they form in mind.  We will probably be talking about them again sometime!

-Alex

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Posted under weather

This post was written by Alex Kirchner on December 8, 2014

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