Desert Phenomenon–Graupel

By Richard Elliott • on January 19, 2011 • Filed under: Desert News, Mojave Desert, Uncategorized

 

Copyright REE 2010

soft hail

The chilling breeze atop Wildrose Peak, in Death Valley National Park, drove me to seek shelter from the wind, on the leeward side of a short rock outcropping.  Still, the 30-degree F. temperature numbed my bare hands, writing in the summit log and eating a snack.  Sitting transfixed on the eastward view of the valley over 9,000-feet below, the fast  approaching storm behind me went unnoticed.  Just before the storm pounced upon the summit, I took notice of the long, gray curtain extending down from the towering clouds.  Swiftly grabbing up my supplies and daypack I ran from the summit, fearing it was a hailstorm that could produce lightning.  Hurriedly, I sought lower elevations, when the storm hit.

Suddenly, landing all around were small, white balls of ice.  They did not strike with the force of a hailstorm, nor rebound as hail hitting the ground.  Mysteriously, the frozen pellets fell to earth softly and quietly, almost like snow.  This strange hail began covering the ground and lodged itself in opened pine cones and on all the desert vegetation.  It was Graupel, a desert and weather phenomenon.

“Graupel forms in the same way as hail except the diameter is less than 5-millimeters,” according  to the Precipitation Types list found on the web site theweatherprediction.com.

Other names for Graupel are soft hail, snow pellets, tapioca snow, or small hail.  As described in Wikipedia, “Graupel refers to precipitation that forms when supercooled droplets of water condense on a snowflake, forming a 2-5mm ball of rime…”

The Graupel experienced on Wildrose Peak fell snow-like, being quiet, sound absorbing and soft as snow.  The storm gave the appearance of polystyrene pellets falling from the sky, as if a giant beanbag had burst open.  The soft hail was very crumbly to the touch.

The first known use of the term ”soft snow” was in 1881, and “Graupel,” from the German usage, meaning “granular snow pellets,” in 1889, according to the web site east.merriam-webster.com/dictionary/soft%20hail.

Soft hail is fluffy, airy, crumbles at the touch and is less than 5-mm in size.  Whereas, hail is precipitation that has turned to ice and these hailstones have a diameter of 5-mm and greater.

Soft hail “falls in shower form, often before or together with snow, and chiefly on occasion when the surface temperature is at or slightly below 32-degrees F,” according to the American Meteorological Society’s Glossary of Meteorology found at their web site amsglossary.allenpress.com.

So, the conditions atop Wildrose Peak were just right for experiencing this unique weather phenomenon

of Graupel.  Had I known that beforehand I would not have had to flee the summit for fear of possible lightning.  I would have been less fearful and enjoyed the soft hail on the summit, as I did along the 4-mile hike back to the car.

Comments

  1. Andrew says:

    Cool story!

  2. John V says:

    The photo is really great. I wonder if the soft hail felt cold and how fast it melted. It must have been a great experience.

  3. Richard Elliott says:

    John, the soft hail stayed on the ground most of the day, probably due to the 30 degree F. temperature. It wasn’t wet, but powdery and crumbled easily. It was an amazing experience.

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