Hi, I'm Dave Thurlow from the Mount Washington Observatory and this is The Weather Notebook. Today we have a question comes from Megan Burt-Kidder, a New Hampshire Public Radio listener:
"I've always been curious as to what the subtle differences are in the atmospheric conditions that allow either sleet, hail or freezing rain."
Well let's look at each one individually. First, hail, which falls mainly during the summer. Hail falls from thunderstorm clouds, which extend miles high into extremely cold air. Updrafts bring raindrops from the bottom of the top of the cloud where they freeze into ice pellets. They then fall only to be blown back up where any coating of rain freezes and the hail stone grows larger, layer by layer. The hailstones, sometimes the size of baseballs, finally overcome the updrafts and fall to the ground.
Now sleet falls in the winter if and when the air temperature is below freezing near the ground and above freezing up in the clouds. Rain forms up where it's warm and falls into the cold air, freezing into little pieces, what we call sleet, on the way down.
Finally freezing rain is almost like sleet except it freezes after it hits the ground forming a glaze of ice.
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