Interesting Weather Information

Monday, October 6, 2014

What is Graupel?

Congratulations to Adams Co. Ohio.

Introduction to Graupel

The first reports of frozen precipitation into the FOX19 NOW weather office this year consisted of observations of graupel (grah - pull) in Adams County on Saturday October 4, 2014.

The term graupel does not mean much to you unless you are a meteorologist or  know the German language.  Even if you do know German the mental image it provokes will not tell you much about what graupel is and how it forms.

Graupel, in German means small hailstone or soft hail both of which will lead you to the wrong conclusions about just what graupel is.

In the United States graupel is used interchangeably with soft hail and snow pellets.  When you see and feel graupel it feels like little snow balls.  So I prefer to use snow pellets or graupel forgoing the term soft hail.

There are a couple of interesting science concepts that you may not be aware of  that explain the formation of graupel.

First a couple photos of graupel.

Via: NOAA, Courtesy: Jodi Paige, Lexington, SC, USA.

Courtesy: Ray Murphy, Montreal, Quebec, Canada.

How Graupel Forms

Copyright: Steven L. Horstmeyer. Permission is granted for use in any non-commercial project.
Copyright: Steven L. Horstmeyer. Permission is granted for use in any non-commercial project.

Copyright: Steven L. Horstmeyer. Permission is granted for use in any non-commercial project.




LT-SEM (Low Temperature Scanning Electron Microscope) supercooled water drops accreted on ice needles.
The resulting accumulation of ice is called rime. Courtesy: USDA Agricultural Research Center, Beltsville, MD.

LT-SEM (Low Temperature Scanning Electron Microscope) supercooled water drops accreted to the extent that the original particles's identity is obsecured. The result is a graupel particle. Courtesy: USDA Agricultural Research Center, Beltsville, MD.

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