Author: Jim Cane and Linda Kervin

Jim and Linda met at the American Museum of Natural History's Southwestern Research Station in the Chiricahua Mountains in southeastern Arizona. They have been exploring nature together ever since.
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Virga

Virga courtesy and Copyright 2010 Kevin Connors
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 is absent from the prose of Mark Twain and the exploratory reports of John Wesley Powell because the word was only coined 70 years ago.

Click to view information from the : 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 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.

Click to view a larger picture of Virga in Tucson, AZ Courtesy & 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,
https://www.weather.gov/jetstream/atmos_intro

Virga in Tucson, AZ Courtesy & 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, https://training.nwcg.gov/pre-courses/S390/FireWeatherHandbook
/pms_425_Fire_Wx_ch_01.pdf

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

Live Worldwide Network for Lightning and Thunderstorms in Real Time, Blitzortung, https://en.blitzortung.org/live_lightning_maps.php?map=30 [Broken link removed 1 Aug 2020]

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SNOTEL Snowpack Recording Stations

Manual Snow Measurement
Cover image from
Snow surveying by James C. Marr
USDA 1940 Publication 380
Public Domain
Courtesy UVA, Google & HathiTrust

For a modern view visit
https://www.meted.ucar.edu/afwa
/avalanche/print.htm

Removing snow surveying apparatus
from canvas carrying case
preparatory to use
From
Snow surveying by James C. Marr
USDA 1940 Publication 380
Public Domain
Courtesy UVA, Google & HathiTrust

Water is a precious resource throughout the world. Most of Utah consists of arid habitats and many users clamor for their share of the scarce moisture. Ever-growing demand challenges water managers to insure that agriculture, cities and nature all get their portion. Predicting and monitoring stream flow is imperative in order to know how much to hold in reservoirs or send downstream, and when to anticipate floods, enact water conservation measures, and in general provide for all users.

Much of Utah’s water originates in the mountain snowpack. Early in the twentieth century, the Department of Agriculture constructed a series of Snow Courses in mountainous areas of the West. Hardy personnel periodically trekked in to measure snow depth with a long ruled stick. Water content was found by taking a core sample, weighing it and subtracting out the weight of the metal tube. Stream gauging stations installed by the US Geological Survey allowed correlation of stream flows with snowpack measures.

In the 1970’s, monitoring snow courses became more automated. The reporting stations were named “SNOTEL” for snowpack telemetry. Now there are over 600 SNOTEL sites in 13 western states. The measurement functions of SNOTEL stations are elegantly simple and reliable. Air and soil temperatures are monitored with standard thermocouples. Water content of the snowpack is measured by its weight atop a broad thin bladder called a snow pillow that is filled with antifreeze. The snow pillow is carefully spread on the ground. Accumulating snow presses down on the pillow, pushing some antifreeze out a connecting tube to a pressure sensor.

Some SNOTEL sites also measure snow depth, using the autofocus technology of the digital camera. Subject distance is gauged by the time delay of an ultrasonic pulse, like sonar or hearing your voice echo back in a canyon. At a SNOTEL station, a similar sensor is placed high above the expected snow line. As snow accumulates, the downward facing sensor reports the shortening distance between it and the snow surface.

SNOTEL stations have batteries and a solar panel to power their hourly data transmissions. Ogden has one of the two master receiving stations. Want to size up mountain snowfall from the last storm or know how warmly to dress for an outing? Just go to Utah’s SNOTEL information site on the web.

Credits:

Image: Public Domain, Courtesy University of Virginia, Google and HathiTrust, Cover image from Snow surveying by James C. Marr, USDA 1940 Publication 380

Text: Jim Cane & Linda Kervin, Bridgerland Audubon Society https://www.bridgerlandaudubon.org

Additional Reading:

Water Conservation Begins with Snow Surveys, USDA NRCS, https://www.wcc.nrcs.usda.gov/factpub/wc_ss.html

Snow Hydrology: SNOTEL, Randall Julander, Civil & Environmental Engineering, University of Utah, (formerly at https://www.civil.utah.edu/~cv5450/snotel/snotel.htm)

Utah Snow Survey Program, USDA NRCS, https://www.ut.nrcs.usda.gov/snow/

NRCS Snow Surveyor Collects Vital Water Data, Lives Dream Job, Spencer Miller, NRCS, Jan 10, 2013, https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/home/?cid=STELPRDB1076993

Snow Surveys and Water Supply Forecasting, National Atlas of the United States, US Department of the Interior, https://www.wcc.nrcs.usda.gov/factpub/sect_4a.html

Map, Utah USGS SNOTEL Stations https://www.wcc.nrcs.usda.gov/snotel/Utah/utah.html

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Feed the Birds

Pine Siskins and an
American Goldfinch feed
feed on thistle from a sock feeder
Copyright © 2008 Jim Cane

Hopper Feeder
Copyright © 2008 Jim Cane

Hopper Feeder with Squirrel
Copyright © 2008 Jim Cane

Suet Feeder
Copyright © 2008 Jim Cane

Many of our songbirds have flown south to spend the winter. I confess that on frigid days I envy them. Like you and I, though, many birds remain behind. They fluff their feathers to trap body heat and spend these short days in a perpetual hunt for food to keep them warm. You can help their hungry quest by feeding our diverse songbirds using a convenient birdfeeder.

For loose seed, I use a hopper feeder. The hopper resembles a tiny roofed house which is filled with seed that is dispensed from a trough at its base. Another common style of seed feeder is a broad tray. It will need a roof and drain holes to keep the seed dry and free of mold.

(https://wildstore.wildsanctuary.com/collections/special-collections)

Our feeder is above a stone walkway for birds like juncos that prefer seed spilled on the ground. A ring of upturned tomato cages around this area excludes cats, and the season’s discarded Christmas tree will provide cover for the birds.

(https://wildstore.wildsanctuary.com/collections/special-collections)

Chickadees and finches prefer black oil sunflower seed, rich in fats and proteins, with a thin shell. If you buy seed mixes, juncos and sparrows will take white millet, but milo or so-called red millet is a filler. Doves and jays like cracked corn.

(https://wildstore.wildsanctuary.com/collections/special-collections)

Goldfinches and pine siskins flock to Niger thistle seed dispensed from a fine mesh sock that you can buy where you purchase the seed. Woodpeckers and nuthatches appreciate a suet feeder, which is a wire mesh cage containing a block of seed-filled suet. Expect magpies to hammer chunks off the suet block occasionally.

Don’t forget water, a scarce commodity for birds in winter. Plug in models remain ice free with scant power use.

Nothing quite cheers a wintry day for me like colorful songbirds noisily bustling at our feeders. If you do put up feeders, consider joining in Project Feeder Watch. You can find details on our Wild About Utah website.

Credits:

Photo: Courtesy & Copyright 2008 Jim Cane, Bridgerland Audubon Society, www.bridgerlandaudubon.org
Text: Jim Cane & Linda Kervin, Bridgerland Audubon Society

Bird Recordings Courtesy and Copyright Dr. Kevin Colver,https://wildstore.wildsanctuary.com/collections/special-collections & WildSanctuary, Soundscapes, https://wildstore.wildsanctuary.com/collections/special-collections

Additional Reading:

Backyard Bird Feeding, US Fish & Wildlife Service, https://library.fws.gov/Bird_Publications/feed.html

Project Feederwatch, Cornell Lab of Ornithology, https://www.birds.cornell.edu/pfw/

How to Attract Birds to your Yard, All About Birds, Cornell Lab of Ornithology, https://www.allaboutbirds.org/Page.aspx?pid=1138

The Great Backyard Bird Count, Birdsource.org, https://www.birdcount.org/

Creating landscapes for Wildlife — A Guide for Backyards in Utah, A production of the Utah Division of Wildlife Resources, Utah State University Cooperative Extension Service & Department of Landscape Architecture and Environmental Planning, https://digitallibrary.utah.gov/awweb/awarchive?type=file&item=10215

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Graupel Snow

Graupel Snow
Image Courtesy & Copyright Jim Cane
Snow graces the winter sky in many different forms. We have large lazy flakes drifting down, sharp needles driven by harsh winds and thick curtains that swiftly blanket the landscape. Late winter storms offer good chances to observe one of our more unusual and distinctive kinds of snowfall; “graupel”. Graupel – that sounds like some kind of respiratory malady, doesn’t it? Also known as soft hail or tapioca snow, graupel consists of tender round snow pellets no bigger than a pea. The name comes from the German word for hulled grain, “graupe”.

Graupel accompanies warmer winter storms, the kind we often have in March, as well as during summer showers high in the mountains. The pellets form when snow crystals fall through a low cloud of super-cooled liquid droplets. The foggy droplets readily coalesce and freeze around the falling ice crystals, accumulating to form soft graupel pellets. The process is somewhat akin to making rock candy from a concentrated hot sugar syrup, or the method used to generate artificial snow. In contrast, sleet forms when raindrops fall through a cold air layer and freeze.

Our big snowfalls are spawned by storms that generate sprawling unbroken cloud decks. Graupel snow, on the other hand, tumbles down from the bellies of fluffy cumulus clouds. As a consequence, squalls of graupel are brief, the pellets accumulating in a thin white bumpy layer, hence the other common name, “tapioca snow”. A buried layer of tapioca snow is prone to avalanche for the first day or two, after which the pellets anneal and stabilize. Any connoisseur of Utah snow should have graupel in their lexicon of wintry terminology, at the ready to impress any Sun Belt visitor met on the slopes.

This is Linda Kervin for Bridgerland Audubon Society.
Credits:

Photos: Courtesy & Copyright Jim Cane

Text: Jim Cane & Linda Kervin, Bridgerland Audubon Society
Additional Reading:

Wild About Utah pieces by Jim Cane and Linda Kervin

Riehl, Herbert: Introduction to the Atmosphere, McGraw-Hill Book Company, 1972 https://www.amazon.com/Introduction-Atmosphere-Herbert-Riehl/dp/0070526567

Rime and Graupel [link removed Oct 6, 2024. Page formerly found at:] https://emu.arsusda.gov:80/snowsite/rimegraupel/rg.html

Severe Weather 101, How does hail compare to other types of frozen precipitation?, NOAA National Severe Storms Laboratory, https://www.nssl.noaa.gov/education/svrwx101/hail/types/ [added Oct 6, 2024]

American Meteorological Society, Glossary of Meteorology [updated Oct 6, 2024] https://glossary.ametsoc.org/wiki/Graupel

Graupel – What is Graupel? https://weather.about.com/od/g/g/graupel.htm