What was that falling from the sky Friday morning? Graupel!
Minnesota enjoys all forms of frozen precipitation
We may be the Land of 10,000 Lakes, but we’re also the land of every type of wintry precipitation too. How lucky are we?
Many people in the Twin Cities metro area saw something white falling from the sky Friday morning, but at closer inspection noticed it was neither snow nor hail. Is it sleet? No. The answer is graupel!
To see what it really was you have to look up close. The best description of graupel is something that looks like Dippin’ Dots.
Sleet looks clear in nature and is more sturdy in nature. It is hard, frozen precipitation.
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Hail forms from intense updrafts in storms that allow super cooled water droplets — liquid water that’s below freezing but not solid — to condense onto snow flake clusters very high up in storms until they become too heavy and fall to the ground.
Sleet is when snow melts and refreezes into a sloppy, crispy mess.
The differences in the precipitation types tell you a lot about the vertical temperature profile of the atmosphere without having to launch a weather balloon.
You can look at precipitation types as essentially a result of how much warm air and super cooled water there is in the atmosphere.
Graupel forms when super cooled water droplets freeze onto snow flakes, a process called “riming.” On Friday morning, a layer of super-cooled water droplets sat at about 4,000 feet above the ground. Snow flakes formed above that layer and fell through it.