Let it snow, or at least be cold
December 16, 2014
With a dearth of snow the past month, the local resorts at least need it cold so that they can make snow. Those cold temperatures appear to have finally arrived and the resorts are excited.
Deer Valley’s director of mountain operations, Chuck English, spoke with The Park Record about some of the ins and outs of snowmaking in Park City.
First, what the resorts make is called "man-made" snow, not "artificial."
"Artificial snow would be the flock you see on a Christmas tree or something," English said. "This is real water that’s frozen and it’s just a little more dense than Mother Nature."
Anyone who visits ski resorts has seen snow guns spraying plumes of cloudy snow into the air. It’s the result of water and compressed air being fired through a small nozzle at high pressure.
"You put it up into the air and as it falls, the compressed air makes the molecules much smaller and they turn into snowflakes, basically. Or snow crystals, as they fall to the ground," he said.
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Because man-made snow is denser than Utah’s light, powdery snowflakes, it’s ideal for creating a solid base early in the season.
"When you groom it, it’s usually much firmer, or as we call it, much more durable," English said. "It’s going to last longer, it’s harder for it to melt once things warm up."
Temperatures dropped quickly this past weekend and are expected to hold the rest of the week. Snowmakers need to factor in one more element, though: humidity.
"What we look at is something called the ‘wet bulb temperature.’ And wet bulb is a combination of the ambient temperature and humidity," English said. "Around here we’re very fortunate that we have dry air, so our ambient temperature is very much like the wet bulb. We start making snow about 27 degrees [Fahrenheit].
"So [Sunday] night we were in the low teens, and that’s a nice temperature — the colder it gets the better" he said. "The colder it gets, the more volume of water you can put in [the snow guns]. You can add a lot of water. I guess there’s probably a point where you could almost just run a Rain Bird [sprinkler system] and make snow if it was cold enough."
Can it ever be too cold for snowmaking?
"Not necessarily, but it starts to become very difficult on the staff and the equipment," English said. "We went all day [Sunday] and we’ve been running snow guns all day [Monday]. It’s nice not to have to shut the guns off completely and drain the hoses, which is what you have to do. When you shut them down, you drain the guns and you drain all the hoses that lead to them so they won’t freeze. If we can just — we use the word "throttle" — the gun back a little bit, so turn the water down and keep it running and making a smaller amount of snow as it warms up. Then as the evening comes back and it cools down, throttle them back up and put more water into them. Which is what happened [Monday]. We got into the mid-20s for higher temperatures so we were able to keep running, but we had to turn the water volume down."
If the wet bulb temperatures cooperate, the resorts can build up snowpack in a hurry.
"With good snowmaking temperatures in the low teens, we can make enough snow on a ski run in two days to get it open. From nothing," English said.
"Now, we haven’t been that lucky so far this fall," he added. Fall will mercifully end this Sunday — the first day of winter.
Water supplies are a big factor for the resorts in winter.
"Edgar Stern, when he bought a lot of the land at Deer Valley he also bought the water rights," English explains. "He gave those water rights to the city to use for culinary water in exchange for us to use water while they don’t need it [in the winter]. For instance, they don’t need it at City Park and the golf course and the school fields.
"We have an agreement to provide us with water to a certain level. Beyond that, we need to start paying as much as anybody else pays for water. And it can get fairly expensive," he said. "Typically, for our mountain, we try to be done with snowmaking by mid to late January on a bad year."
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