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Show Thursday, February 14, 1980 Page 5 That Ineffable t Callec .Elemeii To most of us snow is a simple phenomenon. It's the stuff that cushions and whitens a winter landscape; that makes Up snowballs and deadly avalanches; that forces drivers to relearn every winter the geometry of steering an auto. And, in Park City, snow is, literally, the base of a multi-million dollar ski industry. Yet snow is much more complicated than it seems. The white stuff's physical properties are as varied as its fabled crystal patterns. Eskimos know this and they have dozens of names for snow. Those Eskimos that still travel by dog sled understand different kinds of snow will determine ease of travel, so distances are estimated by time rather than miles. They call falling snow qanit; lying snow aput. An understanding under-standing of snow can properly begin with where qanit forms high in the troposphere. Snow Formation There is some difference of opinion among scientists on exactly how snow forms. Generally though, it is held that snow forms first as ice crystals, which in turn make up the larger snow flakes. Ice crystals form and join into flakes only under certain conditions: First atmosphere and vapor content con-tent must be right for cloud formation, the cloud temperature must be below freezing (usually well below), and, if cloud temperatures are above -40 degrees Celsius, there must be some form of nuclei on which the ice crystals can form. Ice crystal nuclei is of terrestial origin, often clay minerals or mica. Ice and snow clouds usually form around -20 degrees Celsius. In temperate regions, those temperatures are frequently found in the upper troposphere and even higher in tropical regions, usually above 15,000 feet. In very cold regions, ice and snow clouds can appear as fog. And in the vei y coldest regions of Antarctica, snow crystals can form and fall on perfectly clear days. The phenomenon occurs when surface air at -50C or colder, is capped by a warmer layer of air. SuperSaturation takes place where the two air layers meet, generating ice columns and needles called "diamond dust." Diamond dust will descend in an iridescent sprinkle on cloudless days and nights to create all manner of halos, arcs, and coronas in play with sun or moonlight. (Incidents, (In-cidents, snow crystals are clear, not white. Only mass ac cumulation and light intensity make them appear white. Occasionally, Oc-casionally, on a sunny day, blown snow will pass at the correct angle to the sun, splitting light into glittering rainbow colors. Proof again there is more to snow than meets the eye.) Ice crystals, once formed on a nucleus, grow rapidly by attracting at-tracting water vapor in the cloud. Drafts send the light ice crystals on a roller coaster ride through the cloud, with crystals colliding into other crystals to form into larger snowflakes. Portions of the flakes chip off in the collisions, forming nuclei for more crystals, creating a chain reaction of ice crystal generation that turns the cloud into a massive snow machine. After about 10 minutes of growth, the ice crystals are heavy enough to fall from the cloud. Ice Crystal Shapes ."The Greatest Snow on. Earth"., The ofte.n-quoted phrase "no tw4 sriowf lakes SaVe identical may be true, but a recent article in'. CEO. magazine points t out that some 100 decillion (write a one followed by 35 zeros) snowflakes have fallen over Earth's four billion-year history, so it's hard to know for sure. What is known is that like any crystalline ice form, individual snow crystals are six-sided. From there, hexagonal additions can create an endless variety of crystal and flake shapes: flat ornate plates, prickly stars, columns and I-shaped capped columns, thin needles, root-like spatial dendrites, and all manner of irregular crystals. The shape of the ice crystals depends on the cloud temperature tem-perature and water vapor content of the clouds in which they form. And crystal shape determines the character of the falling snow. That's a vital point for Park City and other Utah ski resorts that boast of the best powder around. Climatologicai researchers at the University of Utah note that Utah powder is light and fluffy because of the state's geographical location and topography. As a U of U professor explained it: "During winter, Utah's only moisture source is the Pacific Ocean storms. The state is completely cut off from Gulf of Mexico and Atlantic Ocean moisture. Those storms from the west that hit Utah have been partly dried out by passage over the deserts of Nevada and the eastern Northwest. North-west. Because of the low water density of Utah snow clouds, ice crystals tend to form at rather low temperatures, between -12 and -18 Celsius. These conditions result in ice crystals with a spatial dendritic shape, which gives us powder snowflakes." Powder flakes will change shape as they descend into warmer temperatures. But because Park City and the other resorts are at high elevations, air temperatures are usually sufficiently cold to keep the powder from melting into soggier formWhe flakes stay small, light and fluffy: While Park City is receiving dry powder, warmer Salt Lake City may be getting get-ting large wet flakes good for snowballs from the same storm. Root-like extensions of dendritic Utah powder, keeps the crystals at arms length from each other, so to speak. As Ston By Conrad 15. Klliott and Photos P Pin His M. Uulteiislein - I' ,.'V XT- - J 'J . s if lift" a. :--., t such, the fallen snow may be 90 percenl air. Twenty or more column inches of Utah powder is needed to make a single inch of water; typcial 'Eastern' snow, which is wetter, averages a 10-to-one snowwater ratio. 1 Research on the effects of atmospheric conditions on snow crystal shape has been boosted greatly through photomicrography. Several methods exist for preserving the delicate snow crystals during microscope examination. One of the most common preservation methods seals crystals in a poured or sprayed-on solution of plastic polyvinyl dissolved in solvent. The solvent evaporates shortly after application, and the snow sample can be taken into a warmed laboratory! There the ice evaporates through the thin plastic film, leaving behind a durable hollow shell that can be examined at. leisure ...Another common, and simpler, method involve setting up a cold, Jab, an unhealed; erajni.ng room with hole in the ro6fi in which researchers wait for, a storm to drop samples right to the work place. Mclamorphism Any cross-country skier practiced in the art of waxing can tell you snow on the ground will continue to change crystal patterns, which in turn affects snow hardness and texture. Scientists identify two basic forms of snow recrystalization: constructive and destructive metamorphism. Additionally, there is simple melting and refreezing of snow. Destructive metamorphism occurs as the sharp snow-crystal snow-crystal points melt, releasing water vapor which refreezes again on the crystal, but closer to center. After several day to weeks, destructive metamorphism will turn light powder crystals into rcunded pellets of "old snow." Sun, wind, temperature, tem-perature, and pressure, perhaps fvrom a sliding ski, affect tie. nature, andp4Cft)f,e,me,ta;iiorphiQ process. Pellets af-t,eV( af-t,eV( repeated molting, and refreezing. .become .firn,, Surface, f'i'r'n is often called corn 'snow-a pebbly textured surface that makes for easy downhill turns. y 5 . 5 4 0 Firn layered over and over by succeeding seasonal snows eventually has the air space squeezed out until it becomes iron-hard glacial ice. ..quite a transition from its birth as a fluffy snowflake. Strong temperature gradients can cause evaporation of snow crystals into water vapor that will diffuse through the snowpack and eventually refreeze into depth hoar. Called constructive metamorphism, the process completely alters the ice crystal pattern. The resulting depth hoar is mechanically weak and a frequent cause of once-stable snow packs turning into avalanches and slides. Snow Modification Half the Earth's land surface and nearly ll percent of the sea. or a total of one-fourth the globe's surface, is covered permanently or temporarily by snow. The natural watershed of a winter's accumulation of snow makes possible the summertime sum-mertime navigation of rivers and irrigation of crop lands. Some 75 percent of the water in the rivers of the American West comes from melted snow. Snowfalls of over a 1,000 inches have accumulated in a single season on Mt. Rainier, Washington. Silver Lake, Colorado, received 76 inches of snow in one 24-hour storm in 1921. Utah can't match those records, but during a six-day storm in January, 1965, Alta received 105 inches of snow. During Park City's early mining days, avalanches caused numerous deaths and over the past 128 years, more than 200 people have died in Utah from avalanches. Snow can temporarily cripple a major city, ground aircraft, air-craft, halt street traffic, and otherwise impede man's day-to-day operations. Such a pervasive and potent force has encouraged human attempts for control and modification of snow in the air and on the ground. Before the advent of the automobile, large cities rolled their snow-covered streets to make travel by horse-drawn sleigh easier. Today's local governments spend substantial portions of tax dollars for snow removal on public streets. Military forces have developed special mechanical and chemical snow processing methods that can increase by 2,300 percent the hardness of snowpack in isolated areas, so even behemoth transport planes can land as if on an asphalt runway. Not all human efforts to modify snow pit man in such an adversary role with the white element. Probably inspired by nature's sculpting of snow into spires, cornices, and ripples by sun and wind, man has for countless ages been molding with his hands snowballs, snowmen and snow sculptures. But the most ambitious of human efforts to control snow has been the weather modification of snow clouds through chemical seeding. Cloud seeding to produce snow was first successfully done in 1946 by a General Electric scientist who dropped three pounds of dry ice into a cloud, producing a modest snowfall onto Pittsfield, Massachusetts. A few months later, the Army Signal Corps and the Office of Naval Research conducted a larger scale project, with promising, if unspectacular, results. Scientists thought they may have discovered a means to wrench moisture from clouds at will. However, very'mixied results of seeding operations over'the years shewed the fenOwihakHig process isn't so easily-manipulated. Today, it is known that only certain kinds of moisture-laden clouds at certain stages of development, are responsive to seeding. Particularly susceptible to seeding are supercooled orographic, or mountain, clouds, which form as air currents cool when rising over a mountain. Seeding is done with either dry ice ( solid carbon dioxide) or silver iodide. Dry ice introduced into the cloud from above by plane, or by projectiles or free balloons cools the immediate area to -70 Celsius, cold enough for spontaneous generation of ice crystals. The presence of ice crystals sets off the chain reaction reac-tion of ice crystal-to-snowflake process. Silver iodide seeding works by introducing into a cloud submicroscopic silver iodide particles, which are the ideal size and shape for ice nuclei. The silver compound can be distributed in the target cloud by plane or by a silver iodide smoke generator on the ground. About 75 percent of the weather modification work in the United States is tried in the West. A last-minute seeding operation was attempted in the western states during the 1976-77 drought. Millions of dollars were spent on the program, but many weather experts contend it was a waste of money because it was started so late and there were so few good seed clouds during the dry spell. Such programs, say the experts, need to be initiated early in the season so that thick snow pack, which is more resistant to evaporation, can be built up for water-storage. Finally, there is about snow the quiet way it falls, the starkness and definition elements take against its pure white a feeling mysterious and beautiful. An ineffable sensationsometimes sen-sationsometimes joyous, sometimes lonely that poets have tried for ages to capture, as an unknown poet does in this haiku-like poem : In falling snow a laughing boy holds out his palms ...until they are white Wr Claimjumper Restaurant ATTENTION EMPLOYERS Permanent placements also available MOTHERLODE Temporary Services Reliable on-cll workers lor your eei employment need. WE HANDLE ALL PAYROLL Building Trades. Restaurants. Oltices, Housekeeping. 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