A. V. KOPTYUG, J. STR M, L. G. ANANIEV HOW TO MAKE PERFECT SNOW 123 Each snowflake seemed much larger Dr. Andrey V. KOPTYUG, Ph. D. in Physics, University Lecturer at the than it really was… And how ideal they Institute of Nuclear Physics the Department of Information Technology were! Not a single incorrect line! If only and Media, Mid-Sweden University, stersund, Sweden. they did not melt! Johan STR M, MSc. in Engineering, Managing Director of ARECO Hans Christian Andersen Snowsystem, stersund, Sweden. The Snow Queen Leonid G. ANANIEV, Director, SveRuss Konsult, stersund, Sweden. ГИПОТЕЗЫ И ФАКТЫ alpine ski resorts in the winter of 2003 So, what is necessary to make tiny water droplets are injected into was opened on New Year’s Eve, and snow? Obviously, water at certain the continuous air flow generated by in the winter of 1998—99 only on temperature, dispersed in a certain a high-power fan. January 3d. way, cold air and… some magic or Water-air mixture jetted by the So in winter sports ‘artificial’ snow high-tech equipment — whatever we snow gun needs to spend some time is associated with stability and quality. can lay our hands upon. Now we can floating in the cold air before it drops Snow generating equipment is used say, ’Let it snow’, and let snowmaking down as properly formed snow. Thus, when we want to have a grip over the begin. it is very hard for a fan-type snow situation: there must be enough snow generator to put snow right on the ski anytime we need it, it must be where track; good snow is formed somewhere we need it, and with the quality we A glance into the from 10 to 20 meters away from the can control. It is worth noting that ‘snow gun’ barrel ‘barrel’ outlet. This can be achieved if the main applications of snowmaking we use ‘lances’, which are also cheaper equipment are not confined to skiing These are some details for the than fan-based snow guns, though fan slopes and cross-country tracks. It is inquisitive readers who are not afraid guns provide better performance. also used for testing aircraft de-icing of certain technicalities. There are All modern snow generators include systems and winter tires, and even two major types of snowmaking some automation features, ranging in forestry: to protect young trees machines used today: fan-assisted from simple protection switches (commonly called ‘snow guns’) and Early November 2005. Ski Stadium in stersund (Sweden) is preparing for the World Cup event. In the years of 2003— from frostbites by generating small to complete automated control snowdrifts around them. high-pressure tower-based ones, or systems. 2004 such events were moved to other locations because of the lack of snow ‘lances’. In systems of the first type, Is it easy to make Hundreds of names for snow snow? They say that in northern Scandinavia local people have “To the North Pole with own snow?” This kind of Most people are sure that snow is up to a hundred words for “snow”. It is not surprising: А B natural first reaction can be expected from the readers very easy to make: one only needs in winter there is a lot of it around, and its structure is recollecting Andersen’s immortal ‘Snow Queen’, water and cold weather. Yes, it looks especially when they find out that the authors are living extremely variable depending on temperature, humidity very simple, but appearances could and working in central Sweden, about 500 km north and other factors. Those who are fond of skiing are well be deceptive. So we suggest that of Stockholm (the altitude corresponding to the point aware that snow can be “hard”, “soft”, “wet”, and so on those who live in a cold climate carry about 100 kilometers north of Anchorage, Alaska). And it and so forth. Some days you slide easily, another day you out a simple and safe experiment. almost inevitably will be followed by, “Is 1 m of snow not struggle to gain at least some speed even when going Take a water-spray bottle (the one enough?” Actually, the answer is, “It depends…” If you downhill. are digging your car out in the cold morning after a heavy used for watering houseplant leaves With modern sports, a tenth of a second may decide snowfall for a third time in a week, even 5 cm of snow, or for ironing), fill it with cold tap the fate of skiing medals. With alpine skiing and downhill sure thing, is more than enough. But if you are waiting till water and get out on a cold (say, events, we already speak about a decisive hundredth and mid-January to put on your beloved downhill gear and to below —10° С) winter day. Now, start thousandth of a second. And then the event sport lovers get to the favorite slope, and then outdoor temperature spraying the water high into the air. have been waiting for years is suddenly cancelled when the drops below —25°С and stays like this till mid-April, after Do you think you will get snowflakes? which the snow melts in a week, let’s see what you would tickets and hotels are already booked and paid for. All this No, what you will get is tiny shining say… happens because the Heavens did not send the desperately spheres of ice. So, it should not be surprising that there is someone needed snow to the ‘proper place’, but it somehow managed But how does it happen that these willing to pay for the thing falling from the Heavens ‘for to fall out by your garage doors — yet again. nice fluffy things start floating in the free’. And, consequently, there are people who make the According to the research carried out by the Swedish 124 equipment for ‘manufacturing’ snow. When using proper air as soon as real winter begins? We 125 Regional Climate Modeling Program (SWECLIM), the snowmaking equipment, alpine ski resorts, including the can give you a small hint: it happens annual mean temperature in Sweden is expected to rise ones in Siberia and central Sweden, extend the season high in the skies, snowflakes are by 3.8° C by 2100. Calculations suggest that the warming up to four months (two in early winter and two in spring). the result of slow nucleation of tiny of the Nordic region will be more intense than the global And these are commonly the best four months for skiing, crystals from the mist of the clouds. If average, which can bring a lot of disappointment to winter not too cold and not too warm — perfect for a family the conditions are not right, something In the period of 1990—2100, the climate in northern Europe is supposed to sports fans. Also, the increase in average precipitation will outing else will fall down from the sky: either change dramatically as a result of higher winter temperatures (A) and heavier most probably be due to the increase in the summer and the ice balls of the summer hale, or annual precipitation (B). autumn rains. Together with the increase in the average Figures from the site of the Swedish Environmental Protection Agency, something looking more like semolina winter temperatures it would lead to a lack of snow and Naturv rdsverket (http://www.internat.naturvardsverket.se) or puffed rice (“grainy”, granulated to late openings of alpine skiing seasons both in Sweden late autumn snow). and in Siberia. For example, the season in Eastern Siberian WORKSHOP Artificial snowmaking is actually more than 50 years old. First experimental equipment was tested in the 1950s-1960s in the countries where alpine skiing was popular. Patents on the “procedures to produce artificial snow” were filed as early as in 1968. The photograph shows Engineer Fritz Jakob (behind the snow gun) testing the snowmaking equipment in the mid-sixties. The photo is the courtesy of SUFAG, a member of Snownet Group of companies 126 127 Snow guns in the ‘Bydalsfj llen’- slopes of the ski resort in Bydalen, Sweden. WORKSHOP 54 3 1 2 6 789 Snow guns can also be installed on a caterpillar chassis. 128 129 The heart of the snow gun is formed by the A few static blades, or ‘vanes’ (3), are placed between the fan and the In a fan-assisted snow generator the gun drum (D), together In the ‘lance’, snow-generating elements are air fan (4) generating a high-capacity air flow rings. Their task is to introduce controlled turbulence into the air flow, with the Control and Automation unit (A) and Compressor unit raised up to 10m above the ground. It allows all through the main water nozzle rings (1) and which helps to mix the two snowmaking “components”, water and air. (C), are mounted on a wheel chassis (S) or on a stationary injected water to nucleate properly, while the ‘nucleator’ ring (2). The nozzle rings are supplied Commonly, there are several main nozzle rings, each with its own “leg” (T). The snow gun is connected to the water supply with a formed snow falls to the ground under its own with water; the nucleator rings, with water-air valve, to allow adjustments in snowmaking capacity. All the system special high- pressure hose with a “fast connector” (W). Control weight mixture. is enclosed into a solid drum casing (6) with protective mesh (5) at signals (CS) from the central automation unit come to the snow Nozzle rings inject fine water droplets into the the outlet. gun either by an electric cable or through a wireless link air flow.