Virga: Teasing Rain

Virga: Teasing Rain

Virga courtesy and Copyright 2010 Kevin Connors a.k.a Virga teasing rain
Virga
Courtesy & Copyright 2010 Kevin Connors
August is the perfect month to observe virga in Utah, for it is the monsoon season here. Moist subtropical air is flowing northward from the Pacific Ocean and the Gulf of California. When this warm, moist air is driven upward by convection and mountains, towering thunder heads result.

Below the bellies of these dark clouds you sometimes see grayish windswept curtains or streamers that do not reach the ground. Meteorologists call them “virga”, virga spelled with an “i”, from the Latin for “streak”. The word “virga” is absent from the prose of Mark Twain and the exploratory reports of John Wesley Powell because the word “virga” was only coined 70 years ago.

Virga: Descending Precipitation & Downdrafts

Virga in Cache Valley courtesy and Copyright 2010 Jim Cane
Virga in Cache Valley
Courtesy & Copyright 2010 Jim Cane
These picturesque virga are descending precipitation. One might guess it to be rain, but most meteorologists agree that it is frozen precipitation which is melting and evaporating as it drops through our dry Utah air. Like a home swamp cooler, evaporation in virga causes cooling which leads to the chilly downdrafts that accompany our summer thunderstorms. In the humid tropics, rains can be lukewarm, but our summer cloudbursts are goose-bump cold, owing to the same evaporation which yields virga.

Virga are a tease for parched summer landscapes, a herald of wild fires ignited by dry lightning, and a generator of dust storms as downdrafts scour dusty salt flats. But mostly, the curtains of precipitation that are virga are a fleetingly beautiful element of our western summer skies, well worth a pause and a picture, especially if you are lucky enough to see one accompanied by a rainbow or a fiery sunset.

Virga in Tucson, AZ Courtesy and Copyright 2010 Julio Betancourt, Photographer
Virga in Tucson, AZ
Courtesy & Copyright 2010 Julio Betancourt
This is Linda Kervin for Bridgerland Audubon Society.
Credits:

Photos: Courtesy & Copyright 2010 Jim Cane
Courtesy & Copyright 2010 Julio Betancourt
Text: Jim Cane, Bridgerland Audubon Society

Additional Reading:

Jetstream, an online school for weather, NWS NOAA Southern Regional Headquarters, Ft worth, TX,
http://www.srh.noaa.gov/jetstream/index.htm

Virga in Tucson, AZ Courtesy and Copyright 2010 Julio Betancourt, Photographer
Virga in Tucson, AZ
Courtesy & Copyright 2010 Julio Betancourt

Fire weather : a guide for application of meteorological information to forest fire control operations, Mark J. Schroeder and Charles C. Buck, USDA Forest Service, http://training.nwcg.gov/pre-courses/S390/FireWeatherHandbook
/pms_425_Fire_Wx_ch_01.pdf

The Book of clouds, John A. Day, Sterling, 2005, http://www.amazon.com/Book-Clouds-John-Day/dp/1402728131

Live Worldwide Network for Lightning and Thunderstorms in Real Time, Blitzortung, http://en.blitzortung.org/live_lightning_maps.php?map=30

A Utah Skier’s Snow Lexicon

A Utah Skier’s Snow Lexicon: Utah Skier Brian Head Courtesy USDA Forest Service
Utah Skier
Brian Head
Courtesy USDA Forest Service
Hi, I’m Holly Strand from Stokes Nature Center in beautiful Logan Canyon.

Many linguists believe that the language we use both affects and reflects our experience of the world. A popular illustration is that Eskimos have an unusually large number of words to describe snow—32 or more depending on the source. This diverse snow vocabulary is said to be linked with the fact that Eskimos live in a snowy environment and therefore various conditions or forms of snow are more meaningful to them.

There’s a problem with this example: First of all, the term Eskimo is troublesome. A number of cultures are referred to under the umbrella term “Eskimo” and a number of different languages are in the Eskimo-Aleut family.
Secondly, Eskimo-Aleut languages such as Inuit or Yupik tend to join noun roots and suffixes into one word while the same concept may exist in other languages as two words or a phrase.

Some experts believe that an American skier has just as many words for snow as the so-called Eskimo. There are terms defining different snow conditions in the air, on the ground or in certain formations.
In the air, a single unit of snow is a flake. A lot of flakes blowing at least 35 mph is a blizzard. A whiteout is a blizzard with zero visibility. A flurry is swirling mass of snow moved by sudden gusts of wind. Graupel is snow that has been coated by frozen cloud droplets to form a somewhat spherical shape. Snain is a mix of snow and rain, known offslope as “wintry mix.”

Once it hits the ground, snow ideally exists as champagne powder. Untracked snow is delightful and bottomless powder can be fun but challenging. Snow boarders and backcountry skiers might refer to a fresh dump of powder as phat pow. (As in “Dude, it’s gonna be a phat pow day.”) On a clear cold night when surface hoar forms on top of powder, you can get loud powder which makes a beautiful tinkling sound when you ski over it.

Lightly packed powder is acceptable snow for most skiers. Beginner skiers often look for freshly groomed snow. Snow that has been repeatedly groomed by snow cats creates corduroy snow.

There seem to be a lot more words for snow that reflect less favorable ski conditions. Crud, boilerplate, bulletproof, breakable crust, slush and mashed potatoes to name a few. Corn means that large, loose snow crystals froze at night, melted loose during the day and now act like ball bearings under your feet or skis. Death cookies, or frozen chicken heads form when spring slush refreezes. Utah skiers venturing outside the state might encounter blue ice in the East or Sierra cement to the west.

While you are skiing, you might encounter snow in the form of a drift, cornice, avalanche, bank, pipe, roll or mogul. If children are around you might see a snowman, snowfort or snowcave.

I’ve really just touched the surface here. If you consider all the words for snow, ice and crystal structures and weather conditions, the number of snow words really soars. As snow specialists with a diverse vocabulary, you could say that Utah skiers could give the Eskimos a run for their money.

Thanks to the Rocky Mountain Power Foundation for supporting research and development of Wild About Utah topics.

For Wild About Utah and Stokes Nature Center, I’m Holly Strand.

Credits:

Photo: Travel.Utah.gov

Text: Stokes Nature Center: Holly Strand

Thanks to Jim Akers, Sara Goeking, and Phaedra Budy for their assistance with snow terminology.

Interesting Reading:

Pullum, George. 1991. The Great Eskimo Vocabulary Hoax and Other Irreverent Essays on the Study of Language. University of Chicago Press.