How snow makers work: experts explain how their machines crank out the white powder
While skiers will be cheering the first Antarctic blast of the year that has brought snow to the South Island, ski fields nationwide are still relying on snow machines to build up their bases.
Coronet Peak is turning on its snow machines today and ski area manager Nigel Kerr said conditions this weekend are ideal for creating more snow.
"This first blast of snow is a great opportunity for us to build up a good base as we head toward the season," he said.
The Queenstown ski field has doubled its number of snow guns to 210, giving it the largest snow-making system in the Southern Hemisphere, in an effort to extend the ski season.
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"This year we have the capacity to produce more snow near the base building so our guests will enjoy an even thicker carpet of snow as they hop on the M1 Express," Kerr said.
So, how do snow makers actually work?
Steve Manunui, skifield operations manager at the Whakapapa ski are on Mt Ruapehu, which is also firing up its snow guns this weekend, explained that they are designed to mimic the way snow is made naturally.
In a snow maker, water is forced through a nozzle which turns it into a mist, Manunui said. Compressed air breaks it up into even smaller particles and pushes it through a nucleation box, where it crystalises and turns into ice particles. The icy droplets are fired into the air and, as long as it's cold enough outside, they turn into snowflakes.
"Artificial snow is just made from frozen H2O, just like mother nature does it," he said.
At Whakapapa, which also has double the number of snow makers this season, the machines are placed on towers a couple of metres in the air and a big fan inside a barrel blows the ice particles across the field.
"It just looks like a big fan that fires water," Manunui said.
Traditional snow makers do need mother nature on their side to operate though. The temperature needs to be minus two degrees or lower for them to work, but they have a different way of gauging it than we do. Snow makers go by what is know as the "wet bulb" temperature, which takes into account the amount of humidity in the air and evaporative cooling. The reading is typically lower than the dry bulb temperature (the kind our weather apps use) which is why it sometimes looks like the machines can make snow in warmer weather. Generally speaking, the colder and less humid it is, the more snow can be made.
THE GAME-CHANGING SNOW FACTORY
Whakapapa has invested in a state-of-the-art new machine called the snow factory, which can make snow in all temperatures.
Designed by Italian company TechnoAlpin, the $1.5 million snow factory produces snow crystals inside a temperature-regulated shipping container before spraying them onto the slope.
Having the machine, which it cranked up in Happy Valley three weeks ago, means the ski field can guarantee it will open on June 3 - a month earlier than usual.
"It's very cool new technology," Manunui said. "We're very proud and excited to have such a ground-breaking machine to work with."
Manunui is confident the machine - one of just 10 in the world and the only one in New Zealand - will help to make the season longer than ever, saying Happy Valley will remain open until the Christmas holidays. While they're still figuring out timing, he expects they'll be able to open in time for Easter next year.
He described the machine, which can produce 220 cubic metres of powder a day, as a giant refrigeration system that makes a dry ice product.
It cools gas into a liquid which is then injected into two big cylinders that operate at about minus 30 degrees. Water is then injected around the edges creating a thin layer of icy snow, which is scraped off and placed into a hopper. This then goes into a smaller unit which uses compressed air to force it down a pipe before it shoots out over the valley.
TechnoAlpin isn't positioning the snow factory as a replacement for conventional snow makers, however, presumably aware that the size, price tag and energy usage - it consumes up to five times more energy than a normal snow maker but less water - are too high.
"[It] is more of an addition to the existing snowmaking applications and technologies," the company says on its website. "This type of snow machine is therefore mainly used on other relatively low slope sections or at events in large towns."