Snowmaking

Snowmaking is the production of snow by forcing water and pressurized air through a "snow gun" or "snow cannon", on ski slopes. It is made by relatively large permanent machinery at many ski resorts. The product may be called "artificial snow" or "man-made snow". A snow cannon works by nebulizing water and allowing it to freeze into snow. The device is often used by ski hills and ski resorts to supplement naturally occurring snow and extend the skiing season. Carrying the fresh water to the snowmaking machine often requires an intricate plumbing system, resulting in snowmaking being an expensive and inefficient process.

Snowmaking is too costly to use extensively at big mountain resorts, however it is relied upon at some resorts exclusively due to the variability and amount of natural snow, and for maintaining fresh snow on small high-traffic areas.Fact|date=June 2008 For the purposes of skiing, most enthusiasts consider man-made snow to be inferior to naturally occurring snow.Fact|date=June 2008 This is because man-made snow does not form snow flakes like natural snow; instead, man-made snow forms crystals that are more dense than natural snowflakes.

History

The snow cannon was invented by Art Hunt, Dave Richey and Wayne Pierce in 1950, [cite web|url=http://query.nytimes.com/gst/fullpage.html?res=9900EEDA1631F93BA35751C0A9679C8B63&sec=&spon=&pagewanted=all|title=Machines Let Resorts Please Skiers When Nature Won't|publisher=New York Times|date=2001-02-02] [cite web|url=http://inventors.about.com/library/inventors/blsnow.htm|title=Making Snow|publisher=About.com|accessdate=2006-12-16] who went on to patent it. [US patent reference|number=2676471|inventor=W. M. Pierce, Jr.|title=Method for Making and Distributing Snow|y=1950|m=12|d=14] Snowmaking started to be used on a commercial scale in the early 1970s and is constantly changing to keep pace with the growing ski industry and variable weather conditions experienced at resorts.

Snowmaking efficiency becomes more important to the success of many ski areas every year. This is due mainly to the changes in the climate and the growing popularity of skiing and snowboarding. Many ski areas depend on snowmaking to produce the majority of the snow they require to make it through a season, because the natural snowfall does not normally provide enough snow to withstand the traffic many ski trails see through a season.

Due to recent shift in climate many ski areas have been facing warmer weather unabeling them to use the traditional snow guns. All weather snowmakers have been developed to compensate for those specific needs when snow guns incapable of operating.

Operation

Considerations

Snow cannon constructors have been following these aims:

* to maximize the amount of snow made,
* to extend the period in which snow can be made,
* to minimize the amount of energy needed,
* to minimize the impact on the environment.

Snowmaking plants require very large and expensive water pumps and air compressors that use massive amounts of electricity or diesel fuel. Some systems can use up to 13,500 horsepower at full capacity. A large supply of water is also needed as it takes about 220,000 gallons of water to cover an acre to a depth of 1 foot.Fact|date=June 2008 For these reasons manufacturers of snowmaking equipment are developing more efficient ways to make snow. By doing this, ski areas use less energy and get more production for the same or sometimes less money. Snowmaking has also become more technical over the years as well. Turning to computers to automatically control equipment based on the weather can decrease wasted energy and improve production especially when trying to take advantage of short "windows" of favourable weather. Although technology is helping to improve the snowmakers ability to respond to changing conditions to maintain optimum production, it all comes down to the skilled snowmaker. Snowmaking is a highly physical job that requires dealing with many risks in adverse conditions and requires many skills to do effectively. The efficiency of any system is directly related to the expertise of the operators to make the most of any opportunities.

Wet-bulb temperature is considerably lower than dry-bulb temperature when air relative humidity is low. Wet-bulb temperature takes into account that the water droplets cool themselves by evaporation. Artificial snow can be made when the (dry-bulb) air temperature is as high as 4.5 °C (40 °F).

Water and Air

Snowmaking begins with a water supply such as a river or reservoir. Water is pushed up a pipeline on the mountain using very large electric pumps in a pump house. This water is distributed through an intricate series of valves and pipes to any trails that require snowmaking. Many resorts also add a nucleating agent to ensure that as much water as possible freezes and turns into snow. These products are organic or inorganic materials that facilitate the water molecules to form the proper shape to freeze into an ice crystal. The products are non toxic and biodegradable.

The next step in the snowmaking process is to add air using an air plant. This plant is often a building which contains electric or diesel industrial air compressors the size of a van or truck. Although in some instances air compression is provided using diesel powered portable trailer mounted compressors which can be added to the system.The air is generally cooled and excess moisture is removed before it is sent out of the plant.Some systems even cool the water before it enters the system.This improves the snowmaking process as the less heat in the air and water, the less heat must be dissipated to the atmosphere to freeze the water. From this plant the air travels up a separate pipeline following the same path as the water pipeline.

Infrastructure

The pipes that run along the side of the trail have sets of hydrants mounted on them. They are usually in pairs, one for air and one for water, the pairs of hydrants are usually mounted 50-100ft apart all the way from top to bottom on the trails. Some systems use water pipes and electric supply instead of water pipes and air pipes, see fan guns below. From these hydrants 1 1/2"–2" hoses are connected in a manner similar to fire hoses. The hoses then connect a piece of equipment that is known as a gun and the water and air is mixed to form snow.

Snowmaking guns

There are many different forms of snowmaking guns, however they all share the basic principle of combining air and water to form snow. For most guns you can change the type or "quality" of snow by regulating the amount of water you are adding to the mixture. For others they are simply on or off and the snow quality is determined by the air temperature and humidity.

In general there are three types of snowmaking guns: Internal Mixing, External Mixing and Fan Guns. These come in two main styles of makers: air water guns and fan guns.

An air water gun can be mounted on a tower or on a stand on the ground. It uses higher pressure water and air, while a fan gun uses a powerful axial fan to propel the water jet to a great distance.

A modern snow fan usually consists of one or more rings of nozzles which inject water into the fan air stream. A separate nozzle or small group of nozzles is fed with a mix of water and compressed air and produces the nucleation points for the snow crystals. The small droplets of water and the tiny ice crystals are then mixed and propelled out by a powerful fan, after which they further cool through evaporation in the surrounding air when they fall to the ground. The crystals of ice act as seeds to make the water droplets freeze at 0°C (32 °F). Without these crystals water would supercool instead of freezing. This method can produce snow when the wet-bulb temperature of the air is as high as -2 °C (28.4 °F). The lower the air temperature is, the more and the better snow a cannon can make. This is the main reason snow cannons are usually operated in the night. The mix of all water and air streams and their relative pressures is crucial to the amount of snow made and its quality.

Modern snow cannons are fully computerized and can operate autonomously or be remotely controlled from a central location. Operational parameters are: starting and stopping time, quality of snow, max. wet-bulb temperature in which to operate, max. windspeed, horizontal and vertical orientation, sweeping angle to cover a wider area, sweeping may follow wind direction.

* Internal mixing guns have a chamber where the water and air get mixed together and violently forced out an opening or through holes and fall to the ground as snow. These guns are typically low to the ground on a frame or tripod and require a lot of air to compensate for the short hang time of the water. Some newer guns are built in a tower form and use much less air because of the increased hang time. The amount of water flow determines the type of snow that is to be made and is controlled by an adjustable water hydrant.

* External mixing guns have nozzles spraying water and air nozzles shooting air through the water stream to break it up into much smaller water particles. These guns are sometimes equipped with a set of internal mixing nozzles that are known a nucleators. These help create a nucleus for the water droplets to bond to. External mixing guns are typically tower guns and rely on a longer hang time to freeze the snow. This allows them to use much less air. External mixing guns are usually reliant on high water pressure to operate correctly so the water supply is opened completely and the flow can sometimes be regulated by valves on the gun.

* Fan Guns are much different than all other guns because they require electricity to power a fan and small compressor. The fans propel the water into the air to achieve the hang time and the compressor creates the air needed to operate the nucleator nozzles that are similar to the ones on the external mixing guns. The compressor also allows this gun to operate in an area that has no supply of air from an air plant. Fan guns have anywhere from 12 to 150 water nozzles on a ring that the fan blows through on the front of the gun. These nozzles are usually heated and are arranged in sets or banks. These banks can be shut on or off by valves. The valves are either manual, manual electric, or automatic electric (controlled by a computer).

Home Snowmaking

The same technology used to make snow at ski resorts is now available to the average homeowner looking to make snow at home. Using a smaller version of the snow machines found at ski resorts, home snowmakers are scaled down to run off household size air and water supplies.

A home snowmaker can receive its water supply from either a garden hose or pressure washer/high pressure pump. Home snowguns that receive water from a garden hose make much less snow per hour compared to snowguns that receive water from a pressure washer. This is because designs that use a pressure washer have multiple nozzles with higher flow rate nozzles to create more snow per hour. There are many home snowmaking companies that have snowmaking equipment available for homeowners looking to make their own snow. In addition to snowmakers available for purchase, there are many sites online that offer plans to build your own home snowmaking machine out of plumbing fittings and special nozzles.

Home snow makers can make anywhere from less than an inch to over 6 inches of snow an hour depending on certain air/water mixtures, temperature, wind variations, pumping capacity, water supply, air supply, and other factors. Some snow enthusiasts have spent thousands of dollars to fully automate their own snow systems and design new forms of snowguns based on their needs.

ee also

*All Weather Snowmakers
*Artificial ski slopes
*Snow grooming
*Kern arc - one of optical displays caused by snowgun ice crystal clouds
*Air cannon

References

External links

* [http://www.backyardblizzard.com Backyard Blizzard (BYB)]
* [http://www.makesnow.net Make Snow dot Net: Home snowmakers, plans, parts, and accessories]
* [http://www.snow-maker.com Second Nature Home Snow Makers]
* [http://www.snowstormsnowmaking.com SnowStorm Snowmaking]
* [http://www.snowathome.com Snow At Home]
* [http://www.snowguns.com Snowguns.com]

Snow gun manufacturers
* [http://www.arecosnow.com/default.aspx Areco]
* [http://www.demacsnow.com Demac]
* [http://www.snowgun.com HKD snowmakers]
* Hedco
* [http://lenkosnow.eu Lenko]
* [http://www.Ratnik.com Ratnik]
* SMI
* [http://www.technoalpin.com TechnoAlpin]
* [http://www.turbocristal.com/turbocristal_en.asp?no=7140 Turbocristal]