Figure 1. Global Warming Decreases Snow Cover in the Alps Every Year People's enthusiasm for skiing is on the rise. Regrettably, as global warming increases, the snowbound borderline rises from the sea level and needs to be found The right skiing area becomes more and more difficult. This problem can still be solved by making snow by using equipment such as high-pressure pump systems, but the snowmaking process itself has some problems. In this article, two engineers at Arnold Ofner and Christoph P Pauly at KSB Pump will discuss some aspects of successful snow making. According to the current climate trend forecast, the guaranteed skiing boundary of skiing will recede from 1200 meters above sea level to 1,500 meters in the next 25 to 50 years (Figure 1). As a result, there is not enough snow, outdoor sports in winter will be turned into a bubble. As a result, more and more ski lift operators in the Alps have installed snowmaking systems. Today, the basic technology developed by the United States in the 1950s has been adopted by 90% of ski resorts around the world. More than 1,500 sets of snowmaking systems are in use all over the world and around 500 in Europe. The formation of snow When a large number of moist and warm air meets the cold air layer (air layer) and is cooled, it will form the snow we see in nature. After cooling in this way, the moisture originally contained in the air can no longer remain in it, which in turn becomes precipitation. Precipitation begins to crystallize if the ambient temperature is extremely low. If there is particulate matter (such as dust), the crystallization process will be accelerated. Crystals pass through some layers of air with different water contents and temperatures, and gradually show the snowflake morphology we see (Figure 2). Figure 2. Snowflake artificial snowmaking Snowmaking by mechanical means essentially follows the previously described natural snowfall process. However, there are still some differences between the two: First, the temperature of the water used for making snow must be above 0 ° C, otherwise the water will freeze up from the tank to the snow gun. The nuclei (or seeds) needed to convert water into snow must first be atomized by a jet of pure water sprayed through a nozzle mounted on the snow gun and sprayed from the mist drop to the ground within a short period of time, Nuclei must be transformed into crystalline snowflakes. Thus, this process requires fast supercooling. Snowmaking works better if the ambient temperature is slightly higher, and -3 ° C (27 ° F) is the optimum temperature for snowmaking. If the water temperature is above -5 ° C (21 ° F), only a very small amount of water will pass a given snow gun (the amount of snow will be reduced). Artificial snow should be as "dry" and light as possible to achieve the appropriate physical properties such as high air permeability, low thermal conductivity, easy to freeze, and temperature and humidity characteristics. Snowmaking systems High-pressure spray guns or long guns Typically, long guns are used on steep slopes that are hard to reach. The central plenum and a series of transfer lines deliver compressed air and high-pressure water to individual guns, meaning that each gudgeon is connected to air and water only, ie no external power is required. When the water appears in the nozzle will be atomized. Figure 3. A high-pressure spray gun or long spray gun Compressed air is blown into the atomized water and rapidly expands and cools as it leaves the air nozzle. This rapid cooling effect produces the nuclei necessary for making snow. In order for the nucleus to crystallize enough snow before falling to the ground, long guns are usually mounted as close as possible to 10 meters above the ground, but the downside is that natural wind can blow the snow away from the owner Desired ideal landing position. Low pressure blower snow blower snow blower comes with compressor, you can produce the required compressed air. They therefore require high-pressure water and electricity from the water supply tap, but they do not need compressed air supplied externally. After the high-pressure water and compressed air are mixed and sprayed through the atomizer, the high-pressure air expands and simultaneously cools the water and the surrounding air, thereby producing ice crystals (crystal nuclei). At the same time, atomized water emerges from a circle of nozzles on the periphery of the nucleation nozzle, causing the ice crystals to crystallize. Large fans blow the mixture up overhead, maximizing the time it takes to crystallize the snow. Most impeller snow guns are mobile and can be towed by helicopters or snowmobiles to the point where they are needed, and the underground hydrant at the point of attachment can be pinpointed to where snow is needed. Figure 4. Low pressure snow gun snowmaking water The water needed to make snow can be extracted from outdoor natural waters, reservoirs (reservoirs) and even extracted from local drinking water supply systems, but sources of water from the latter or underground For snowmaking temperatures are too high, you must first make snow before