Snowmaker with standard "air gun"
(click to enlarge)

Overview

In sunny, semi-arid Southern California, Big Bear Mountain Resorts relies heavily on its huge snowmaking systems to provide quality snow for hundreds of thousands of skiers and snowboarders each season. We make snow whenever we can from early November into March, even if it's a good year for natural snow, so as to ensure the best possible conditions all season long. Aggressive, large-scale snowmaking allows us to rapidly open new runs and lifts so that by the Christmas holiday period we usually have most of the mountain open with a good solid snow base with few or no bare spots. Each resort covers hundreds of acres of ski runs each season with an average of three feet of solid man-made snow, the equivalent of about ten feet of natural snow.

Large amounts of water and power are needed for big time snowmaking. Several hundred million gallons of water supplied by Big Bear Lake are converted into snow each season.  In ideal conditions we reach flow rates of 5,000 to 6,000 gallons per minute (gpm) at each resort for several days and nights, non-stop. Approximately 24 ½ megawatts of power are needed for Big Bear Mountain Resorts to run the snowmaking equipment, consisting of air compressors, water pumps, fan guns and hill lights. Power is supplied both through the local electric company and by on-site diesel driven generators. Several million dollars each season is spent in producing the snow and millions more have been invested in the equipment and systems that produce it. The following provides basic information on these amazing systems that produce the snow that makes skiing and snowboarding viable in Southern California.

Bear Mountain "air gun"
(click to enlarge)

Snowmaking Basics

Man-made snow is real snow (not “artificial”) made by “guns” spraying atomized water particles under high pressure into the cold dry atmosphere, which freeze into snow particles before they hit the ground. The colder and drier the air, the more water can be put through the gun. No additive or chemical is put in the water.  The only difference between natural and man-made snow is that the latter falls as small round pellets due to the air turbulence, while natural usually comes in the form of small to large flakes.  However, in windy conditions even natural snow will be blown into small pellets or even marble-sized balls called “grapple”.  Natural snow can be very wet or dry, depending on its water content, the same as with man-made.  After two or three days on the ski runs, natural snow becomes indistinguishable from man-made as both are subject to skier traffic, grooming, and the freeze/thaw cycle.

Buried Pipelines

Many miles of buried steel air and water pipe lines, from 2 inches to 2 feet in diameter, deliver the high pressure water and air throughout the mountain. Attached to the main lines are hydrants placed on the sides of runs, every 50 to 150 feet or so. Each resort has about 500 hydrants lining its runs. The “air” guns are attached to the hydrants by air and water hoses and the “fan” guns by water hoses and electrical lines.  The guns are placed exactly where the snow is to be made and when enough snow is made at one location, they are moved to another.

The Guns

We use two types of snowmaking guns. One uses compressed air mixed with water at the gun (which is really just a tube with a small nozzle at the end) to atomize the water into particles small enough to freeze quickly. The other “airless” type uses an electric fan in a 5 foot long by 2 ½ foot wide tube that pushes an air stream into which small particles of water are sprayed by dozens of tiny nozzles on the rim of the tube.  (Fan guns aren’t completely “airless”; there is a small on-board compressor that helps to atomize the water at the nozzles.) If we just sprayed water straight out from a hose, without atomizing the water, it would be like rain water droplets that are too big to freeze before they hit the ground, which would then freeze on the ground as ordinary ice. The colder and drier the air, the more snow can be made at each gun since more water can be introduced into the outside air mass because it can freeze faster. In 2006, about 70 “airless” fan guns and about 80 “air” guns can operate at one time at Snow Summit alone.  Bear Mountain operates about 45 fans and 90 air guns respectively.  (We actually have several types of air guns, but they all function basically the same way.) A number of both types of guns are mounted on towers, from 6 to 20 feet high.  While they can’t be moved to put the snow exactly where desired, they produce more snow than guns close to the surface because there is more “hang time” for the water particles to freeze before they hit the ground.

Fan Gun Technology

The newest fan guns are almost completely automated. Each has an on-board computer with a weather monitoring station that assesses the snowmaking conditions nearby and then adjusts the water flow when conditions around the gun change (temperatures, wind and humidity frequently vary from place to place and from time to time around the mountain). While our crewmen continue to check these new type guns periodically, their constant adjustment to changing conditions means much greater efficiency and more consistent quality.

Tremendous Snow Production

Each gun can produce an amazing amount of snow in good conditions (5% to 20% humidity and 10° to 20° F), much faster than Mother Nature.  A compressed air gun can convert about 70 gallons per minute (gpm) into snow while a fan gun can convert up to 200 gpm in those conditions. (Consider that a garden hose puts out about 3 to 5 gpm.) So, in ideal conditions, each resort’s system can convert about 5,000 to 6,000 gallons of water per minute into snow! That’s a good sized stream flow that could fill a backyard pool in about 5 minutes! If a gun is left unmoved in those conditions, it can make several feet in front of it in a few hours, sometimes burying itself.

We can’t put 5,000 gallons per minute worth of snow on just one run at a time due to the limitations of pipe sizes and number of hydrants, so instead, we make snow on several runs at one time and might put an average of one foot of snow down on each. In normal snowmaking conditions we can open a run in about 48 hours of snowmaking over bare ground. At the start of the season, we typically open several runs and lifts after a couple of days and nights of snowmaking, and open still more soon after that. 

Snowmaking Quality Controls

Man-made snow is usually made very dense, having about 35% water content as compared to natural snow that usually has only about 5% to 15% water volume. Early in the season it’s made wetter to provide a solid base that prevents skiers and boarders from scraping it off to the bare ground below.  But one of the biggest mistakes is to allow a gun to run too wet, which makes slush instead of snow, which then freezes into ice – highly undesirable from a skier’s or snowboarder’s standpoint. 

The consistency of the snow is controlled by adjusting the amount of water that is allowed to mix with the compressed air or the fan gun air stream. Big Bear Mountain Resort snowmakers are very conscious of snow quality. Once a base of 1 to 2 feet is put down, lighter snow is made to make the best possible conditions.  We can even make extremely dry, powdery snow, but that is less efficient in terms of the energy outlay.

Snow Summit, Big Bear Lake in foreground
(click to enlarge)

Snowmaking Water

The practically unlimited water source for Big Bear Mountain Resort’s large scale snowmaking is Big Bear Lake. It’s pumped from the lake to the resorts and then up the mountains. Multi-million gallon reservoirs on the resorts store water for heavy production because the lines from the lake can’t flow enough water at those times. This lake water supply is the main reason Big Bear’s resorts can virtually guarantee skiing on most runs all winter long, even in the driest winter. Throughout the season, Summit and Bear each can produce at least twice the snow of any other local resort, which rely on limited amounts of on-site well water.

We have an annual allotment from the lake that we have never needed to exceed.  If used entirely, it would draw the lake level, when full, down only about 4 inches – and at least 50% of that runs back into the lake during the spring snowmelt!

Snowmaking plant at Bear Mountain
(click to enlarge)

Energy

Snowmaking requires a great deal of energy to run the pumps, compressors and fan guns, which is much more expensive than the water and labor costs. Bear Mountain uses mostly electric power provided by the local utility company while Snow Summit produces most of its own power by diesel driven generators in big plants at both the top and bottom of the mountain. Snow Summit also has night lighting on most of its runs for both night skiing and snowmaking operations that also requires electrical energy.

The air compressors need huge amounts of energy to provide the air flow for the air guns. Each air gun uses 300 to 1,000 cubic feet of air per minute (cfm), depending upon how big the nozzle is and how much water is put in, at about 85 to 95 pounds per square inch (PSI) pressure. Not counting water pumps and hill lighting power usage, about 9,600 kilowatts are needed to run all Snow Summit’s air compressors while only about 3,000 kilowatts are needed to run all 70 of its fan guns. While the traditional compressed air guns can produce snow in marginal conditions when the fan guns can’t, we are increasing our use of fan guns because they can produce a lot more snow in most conditions for the same amount of power.

Snowmaker with "air gun"
(click to enlarge)

Manpower

While some snowmaking systems are nearly 100% automated, Big Bear Mountain Resorts rely heavily on skilled labor, although some of the newer fan guns are mostly automated. Crews of 10 to 20 men work day and night, when conditions permit, moving and setting the guns in place and adjusting the air/water mixtures. This is done by standing in the snow landing area in front of the gun examining the particles as they fall on their sleeve – or, pinching a bit of snow on the surface to test its consistency.  If a little more or less water is needed, they signal to a man at the water hydrant to make the adjustment.  They usually move around the mountain on snowmobiles and check and adjust each gun every hour or so. They are outfitted in waterproof suits with gloves, boots and ear protection (necessary because of the noise). They work long hours in some pretty adverse weather conditions, but it is very rewarding work as many of them ski or snowboard and take great pride in producing a product they use for their own pleasure when they have time off.

Cat blading into mound of manmade snow
(click to enlarge)

Grooming

Grooming by snowcats pushing and tilling the man-made snow is an important element in providing good skiing. While the snowmaking guns are moved frequently, there typically will be piles left in front of each gun which must be graded into a smooth, relatively flat surface before operations. After a good period of snowmaking some of these snow mounds may be as big as a small bus and are called “whales” by the crew. After the new snow is spread evenly, the surface is gone over with a tiller on the back of the cat, which is a sort of grinder that pulverizes the top 3 to 6 inches of the snow to give it the ideal texture for skiing or boarding. Grooming is a real art to know when and how to push the snow around and condition it into a good grippy surface preferred by skiers and snowboarders. Fresh man-made snow is nearly always groomed into a consistently good surface prior to opening.

Final preparations for opening
(click to enlarge)

Santa Ana Winds

As mentioned above, dry air (low humidity) is very helpful to snowmaking and actually is as important as temperature. It allows, through evaporative cooling, more water to be converted into snow than does moist air at the same temperature. Believe it or not, the resorts can make very good snow in bone dry air with the temperature at 35°, yet struggle at 25° in a cloudy, foggy atmosphere.

Everyone knows Santa Ana winds are dry, but what many don't realize is that they are usually cool – sometimes very cold – as they come out of Utah and Nevada. These winds are heated by compression when they enter the valleys of Southern California. So, even though it may be beach weather in the cities, they are usually very good for snowmaking.