Types Of Winter Precipitation

Winter Precipitation
Tuesday January 24, 2017

Traditionally, everyone associates winter with snow here in New York. However, there are really four main types of precipitation that we routinely experience. The four types of precipitation are determined by the thickness of layers of cold and warm air above the ground.

1. Snow
Snow is the most straight forward winter precipitation. It happens when the entire layer of air from the ground to the clouds is below freezing. The clouds drop ice crystals (aka snowflakes), and they simply remain frozen in the cold air.

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Caption: Snow is the fluffiest precipitation.
Click image for larger version.

2. Sleet
Sleet happens when there is a wedge of warm air above the surface of the Earth. Falling ice crystals pass through the warm air, partially melt, but then refreeze before reaching the ground. Sleet can vary in appearance from clumps of miniature-looking snowballs to clear ice pellets. Because sleet is denser than snow, it can weigh much more when being shoveled and it usually doesn't accumulate as deeply.

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Caption: Sleet can appear like snow, but is usually more bead-like.
Click image for larger version.

3. Rain
Rain is almost as straight forward as snow. During rain a thick layer of warm air extends well above the ground. If the warm layer of air extends all the way to the clouds, precipitation will begin falling as rain drops, otherwise the falling ice crystals will melt once they reach the warm layer. The drops remain liquid when they reach the ground.

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Caption: Rain is rain; we all know rain.
Click image for larger version.

4. Freezing Rain
Freezing rain forms the same way as rain, but with one VERY important exception. During freezing rain there is a thick layer of warm air above the ground, but very thin layer of cold air on the ground. This means that the precipitation is liquid (rain) while it is falling, but once it hits the ground it freezes into ice. Because a sheet of ice can easily form, freezing rain is usually the most dangerous of all the precipitation types.

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Caption: Freezing rain can be treacherous because it can look wet like rain.
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Precipitation summary

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Click image for larger and clearer version

-Ethan

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