Artificial Snow

Artificial Snow

Artificial snow is small particles of ice that are used to increase the amount of snow available for winter sports such as skiing or snow boarding. It is produced by a machine that uses a high-pressure pump to spray a mist of water into the cold air. The water droplets subsequently crystallize to form fake snow. The first commercially successful machines were developed in the 1950s and improvements in technology have steadily been introduced. With the increase in the popularity of winter sports, the artificial snow market is expected to show significant growth.

Background

The machines that produce artificial snow are designed to mimic the way that natural snow is made. In nature, snowflakes are formed when the temperature falls below 32° F (0° C). Atmospheric water then condenses on particles in the air and crystallizes. This action produces snowflakes that have a variety of sizes and shapes.

In a snow machine, water is first mixed with a nucleating material. It is then pressurized and forced through an atomizing nozzle. This breaks the water up into a mist, which is then injected with compressed air to break it up even further. As it exits the snow machine, the mist crystallizes on the nucleator and turns into tiny snow-like ice particles. Depending on the quality of the snow machine, the artificial snow can be as good as natural snow.

History

Although archeological evidence suggests that humans first skied about 4,000 years ago, interest in this activity as a sport did not begin until the middle of the nineteenth century. In 1883, the first international competition was held in Norway. The sport soon spread to the rest of Europe and America. As the popularity of skiing increased so did the need for a device that could provide snow when it was not naturally available. This need led to the development of the first artificial snow making machines.

One of the first machines was patented in the early 1900s. While it was functional, this machine was crude and unreliable. Steady improvements in design led to the development of a compressed air snow-making machine in the 1950s. This machine worked by using compressed air to force water through a nozzle. The nozzle would break the water up into smaller droplets, which would subsequently crystallize. The Pierce device, named after its inventor, was effective enough that most ski resorts used it. However, it did have its drawbacks, most notably, the nozzle tended to clog and it required a very high amount compressed air. This made it expensive to run. Additionally, the machine was quite noisy, and the snow that it produced tended to be wetter and icier.

During the 1970s, a variety of new innovations were introduced to the machines that improved the quality and method of producing artificial snow. One improvement was the addition of a rotating base and fan. The fan would blow the newly created snow farther away from the machine than compressed air alone and the rotating base allowed the direction of the snow to be changed. This made it possible to cover a much larger area with a single machine. Another improvement was the introduction of a ducted-fan machine. These machines were portable, making it possible to use them all over the ski run. They were superior to compressed air machines because they were significantly quieter and were less expensive to run.

In 1975, a nucleating agent was discovered by Steve Lindow, a graduate student at the University of Wisconsin. While investigating a method to protect plants from frost damage, he found a protein that attracts water molecules and helps them form crystals. It was soon realized that this would be a useful material for making artificial snow. The material was then trademarked and is now sold under the trade name Snomax.

As electronics improved, so did the controls for artificial snow-making machines. Computer controls were added, as were sensors that could automatically detect snow requirements. Higher powered fans were also added. Various other innovations led to machines that could produce better snow and more of it. Today, nearly all ski resorts employ some type of artificial snow-making system to improve skiing conditions and increase the length of the ski season.

Raw Materials

Water is the primary ingredient required to make artificial snow. Since ski areas are located on mountains however, finding an appropriate water supply is often a problem. If rivers or creeks are nearby they may be used. Otherwise, ponds or dams are created at the bottom of the mountain to produce a storage supply of water. The water is then pumped to the snow-making machines when needed.

In addition to water, compressed air and a nucleating material are also required to make snow. The compressed air is obtained using a pump. The nucleating agent is a biodegradable protein, which causes water molecules to form crystals at a higher temperature than normal. It is obtained from a nontoxic strain of a bacterium called Pseudomonas syringae. On average, this material can increase the amount of snow produced by a machine by 50%. It also helps produce lighter, drier flakes.

Design

The most important part of any snow-making system is the snow-making machine called a snow cannon or snow gun. A variety of designs are available, however most contain common elements including compressors, pumps, fans, and controls.

A central piece of the snow-making machine is the fan assembly. This part is responsible for converting the air/water mixture into tiny droplets and blowing it out onto the slope. It is similar to a typical portable house fan. It has a rotating propeller blade attached to a variable speed motor. Attached to the blades are curved vanes that direct the flow of air in a linear fashion. The fan is encased in an elongated steel duct that is open on both ends. As the blades of the fan move, air is drawn in from one side of the duct. This side is covered with a screen to prevent foreign objects from entering the assembly. The mechanisms controlling the main ingredients of the snow are located in the front, or discharge end, of the fan duct. This includes a water spray, compressed air pump, and a nucleating device. The nucleating device contains a reservoir filled with a nucleating agent. Water is pumped through this reservoir and the protein is incorporated.

During the snow-making process, the fan assembly is attached to a variety of pieces. To get water and air, hoses are hooked up to the fan assembly. These hoses are connected to a series of compressors and pumps that move air and water through pipes, up the mountain. To increase the coverage of the snow, the fan assembly is mounted on an oscillating stand, or yoke. Depending on the design, the placement of the yoke can be just off the ground or attached to a high tower. Levers may be connected to the yoke, which can adjust the angle at which snow exits the machine. A control box for the machine is typically located at the base of the yoke. This includes switches to operate things such as the water flow, fan rotation, and oscillation speed. The control box may be operated by a remote computer.

The Manufacturing
Process

The production of artificial snow requires a series of devices that can move water and air up the mountain, combine them with a nucleating material, and spray them into the air as small droplets. Typically, the system is installed during the summer months and operated at night after the slopes have closed.

Installation of the system

• 1 Artificial snow making requires an entire system to be installed on the mountain slope. This system includes a series of water pipes, electric cables, pumps, and compressors in addition to the snow making machines. First, plans showing the layout of the system are drawn. Then the water pipes and cables are laid in long trenches traversing the entire slope. The trenches must be dug significantly deep so water does not freeze during the winter months. At various points along the water line, valves and hoses are installed to bring water to the surface. Hay bales are placed around them for protection.

Mixing water with other components

• 2 Snow making is typically done at night and requires constant monitoring. It is typically only done when the outdoor temperature is 28° F (-2.2° C) or below. A number of snow machines are hooked up to the water lines all the way up the slope. When the machines are turned on, the snow making process begins. The water is first pumped up the mountain to the various machines. Depending on the type of machine, water may be mixed with the nucleating material prior to pumping or when it first enters the machine.

Creating the snow

• 3 The water is then mixed with compressed air and pumped through a high powered fan. The fan can spray the mixture nearly 60 ft (18.3 m) into the air. As it leaves the machine, the water crystallizes and forms snow. The snow is piled up is large mounds known as whales. At this point the snow may be analyzed and the machines are adjusted to produce the best quality snow.
• 4 When a pile of artificial snow is significantly high, the snow making machine is turned off. At optimal performance, a snow machine can produce enough snow to cover an acre in about 2 hours. The whale is then allowed to set, or cure, for two to three days. This lets excess water drain off and helps produce a softer snow.

Moving the snow

• 5 After the curing process, the snow pile is ready for grooming. Using a special plow, the snow is smoothed out onto the skiing surface. While it is being moved, it is sent through a tilling device. This fluffs up the snow, making it more skiable.

Quality Control

Producing artificial snow that is as good as or better than natural snow requires significant quality control measures. Prior to production, the nucleating material is checked to ensure that it meets the appropriate specifications. While the snow is being made, it is analyzed for crystal quality, appearance, and wetness. The air/water ratio may be adjusted to improve the quality of the snow. If the snow is of the highest quality, it will last longer, hold its shape better, and be easier to groom.

The Future

The shortcomings of the current artificial snow-making technology suggest possible improvements in the future. Currently, the noise generated by these machines is a problem. While attempts have been made to reduce the sound, future machines will be even quieter. Another limitation of the snow-making machines is their narrow temperature range of operation. New machines may be able to produce snow at temperatures over 28° F (-2.2° C). These machines may also produce higher quality snow in less time.

Where to Learn More

Periodicals

Brown, Rich. "Man Made Snow." Scientific American (January 1997): 119.

Hampson, Tim. "The Bacteria at the Heart of a Good Snowfall." New Scientist (January 1990): 38.

Other

Weaver, et. al. U.S. Patent #5,400,966,1995.

VanderKelen, et al. U.S. Patent #5,167,367, 1992.

—Perry Romanowski