At first thought, it might not seem like making snow would be very difficult. It's just simple frozen water, right? Actually, making enough snow for an entire ski mountain is a very complex and delicate procedure that depends on a lot of different variables in order to be successful. The contours of the terrain, natural snowfall, sun exposure, air and ground temperature, humidity and wind variations are just some of the factors that must be considered.
Mother Nature makes a lot of the decisions on a ski mountain. If it won't snow, it just won't snow. Unfortunately, snowmaking isn't a cure-all for unfavorable ski conditions. The weather has to be just right, otherwise the guns won't produce snow or they will produce very little of it. It's up to the professional snowmaking team at Seven Springs to decide when the time is right!
There are three vital ingredients in snowmaking: water, compressed air and proper outside temperature. Snowmaking can begin at 28 degrees if the humidity is low, but the quantity of snow produced in those conditions is minimal. At 26 degrees and lower, the snowmaking really starts to get going and one to several inches can be produced each hour. The colder the conditions get, the more snow the guns can turn out.
The outside air temperature is a rough guide for determining when snowmaking can begin. As temperatures drop from the upper 20s, the snowmaking team will start using test towers to monitor the conditions. When the team determines that the time is right, they will start up the equipment and begin making snow.
Wind direction also plays a big role in whether the snow will fall where it is needed. If the winds are not favorable for the stationary equipment, the team may choose to set up portable equipment to cover the desired areas.
Once the system has been fired up, it's time to start making some snow! The process begins with the key ingredient: water. The water used for snowmaking is collected in ponds all over the resort property. This water is pumped to the top of the mountain and stored in Lake Tahoe until it is needed.
Lake Tahoe is the final stop for the water before it enters the snowmaking system. From the pump house at the lake, water is pumped through miles of underground piping to approximately 1,200 snowmaking stations lining the slopes and trails. Once at the station, the water is delivered through a frost-free hydrant to the snow gun, where it is combined with compressed air and shot out of the gun as snow.
Once the water reaches Lake Tahoe, it must be cooled down. Ideally, the water temperature used for snowmaking should be in the mid 30 degree range. Circulating the water helps cool the lake down to the proper temperature range. Aerators and a fully solar-powered circulation system called the SolarBee keep the water moving and at a steady temperature. The SolarBee is capable of circulating about 14.4 million gallons of water per day!
After spending the winter on the mountain, the snow inevitably melts. The melt water replenishes the holding ponds at the base of the mountain and recharges the groundwater below. The ponds also collect rain and runoff and the same water is used again and again every winter. Whatever water is used on the mountain, stays on the mountain!
The snowmaking air comes from large air compressors that produce 28,500 cubic feet per minute. Like the water from Lake Tahoe, it is also distributed through the miles of underground piping to the snowmaking stations. At the station, the air is distributed through a hydrant to the snow gun.
One of many extensive efforts to reduce the resort's carbon footprint, Seven Springs recently replaced its diesel air compressors with electric-powered compressors. There are currently five 900 horse power centrifugal air compressors that power the air through the snowmaking system.
The Snow Guns
Seven Springs has several types and sizes of snow guns to suit various applications, but they all function essentially the same way. The water and air are forced through the gun under pressure. This pressure creates tiny water droplets which freeze as they enter the freezing ambient air. This produces a snowflake lattice structure similar to natural snow.
Various conditions can yield different snow textures from wet and sticky to dry and powdery. Once the snow is on the ground, it must be finished into a skiable surface. Our fleet of groomers (snowcats) levels all of the snow, moves it to where it is needed and grinds it up to provide an ideal skiing surface.
There are more than 1,000 snow guns that cover 95 percent of the 285 skiable acres. The variety of equipment across the mountain is part of the resort's constant commitment to improving snowmaking and the experience of the guests.