Slippery science

From man-made snowflakes to skis and boards that are easier to turn, 3-D computer modelling of jumps to advances in telecommunications that have flattened learning curves, science has made great strides on the slopes, writes Shane Gilchrist.

When Cesar Piotto talks about old snow-sports equipment, he's not referring to the rudimentary wooden runners and root bindings used by Stone Age hunters in Europe and Asia more than 6000 years ago.

In fact, one need go back only a decade or two to see marked differences in the equipment used to get from A to B on a ski field.

''If you were to pull out a pair of skis that were 20 years old, versus a new pair, you'd find they are very different,'' Mr Piotto, NZSki's general manager for snow sports, says.

''Twenty years ago, I would have skied on a 195cm pair of skis that were dead-straight. Now, skis generally tend to be shorter and fatter and taper in the middle.

"Because they are shorter, it is much easier to turn; and because they have an hourglass shape, once you put them slightly on their edge, they bend, naturally forming an arc along which they want to travel.

''Because people can do it with less effort - they get more comfortable and independent - their skills improve so they can explore more of the mountains.''

Responsible for more than 400 staff at NZ Ski's snow school operations at Coronet Peak, Remarkables and Mt Hutt ski areas, Mr Piotto says there have been major advances in snowboard technology, too.

''Learning to snowboard now is quite a different experience to what it was seven to 10 years ago. The boards flex differently so it is easier to engage a turn.

"There are what are termed 'rocker' boards, which make it easier for learners to not catch edges and fall over; they avoid going through a tortuous first few days.''

Communications technology has also accelerated the learning process.

These days, people employ the time spent sitting on a chairlift to watch video clips of techniques, tricks and tips on their mobile devices.

''One of the biggest tools available to our instructors is technology,'' Mr Piotto says.

''If you and I went skiing, I could video you through my phone then launch an app that allows me to pause and draw arrows showing what different forces are at play; compare your run with previous runs.

''We can do this while we are on the chairlift, meaning we can do a play-by-play analysis of what's working and what's not working and what we can do to improve.

''We can immediately see something and respond to it. I might have been talking to you for days about how you keep your hips too far back, but if I can show you exactly what you're doing wrong ... some people really need that visual cue.''

Still, older methods are also employed, Mr Piotto notes.

''I might need to poke you in the back of the leg to show what muscles need to fire.

''We refer to that as learning style. Instructors refer to that every time they deal with people. Within a group of, say, six people, everyone might be slightly different or require a mix of approaches.''

Creating a crystalline cloak
''I see it as a snow factory. There is this factory of steel and spinning, moving parts. And there are guys willing to do whatever it takes to keep those machines running in incredibly trying conditions.''

Pete Deuart, head of snow-making and grooming at Coronet Peak, is referring to the important business of snowmaking, a process that has benefited greatly from advances in technology.

A modern snow fan typically comprises one or more rings of nozzles that inject water into the fan air stream.

A separate nozzle or group of nozzles is fed with a mix of water and compressed air to produce what is termed the ''nucleation point'', or the initial process in crystallisation.

Small droplets of water are then mixed with the ice crystals and propelled out by the fan, after which they further cool through evaporation in the air.

And the temperature doesn't necessarily have to drop below zero for snowmaking to commence.

''If it's 100% humidity, then we need -1.8degC; but if it's 20% humidity we could make snow in 3degC,'' Mr Deuart explains.

''Basically, we set the parameters for the factory, so to speak. When it reaches a certain temperature, the guys go on up and make sure the snow is going where it's meant to and the machines keep going.

''The biggest innovation in the ski industry has been automation of snowmaking. We've gone from having probably 20 guys running 50 guns - and never making snow unless we had at least a four-hour window of optimum temperature - to 10 guys with 215-odd guns making snow if we get a half-hour window.

''The quality is far better now. If the temperature isn't right, the gun automatically turns off.''

There are different types of man-made snow, too.

At the start of the season, snowmakers will produce harder snow in an effort to flatten all those alpine tussocks, ''to get a good feel over the grass,'' Mr Deuart says, adding such an approach also means machinery won't damage the subsurface.

''We have a motto: let's make it better. That might sound boring, but if you've got grass or rocks, what's better? Any sort of snow. And what's better than that?

"Good snow. And so on. It's about continually trying to improve the snow surface for skiers and riders.

''It is always changing. When we get rain, that will percolate through the snow pack and round off the crystals.

''If we are not getting natural snow, the best thing we can do is make a little bit of snow every night to ensure there are new, fine crystals intertwined with the old crystals.

"If we get a spell of, say four weekends where we can't make snow, then we get this 'sugary' snow. The snow crystals become almost like hail crystals; they slowly break down and don't bond with anything.''

A few words on wind slabs and wet slides
The field of avalanche assessment might have benefited from the advent of automated weather stations, yet there's no substitute for years of field experience, according to Simon Howells, snow safety officer at Treble Cone Ski Area.

''The main tool that we have now that we didn't have 10 years ago are the remote weather stations. These provide information in relation to snowfall and the speed and direction of the wind through the course of a storm.''

However, that data is merely part of a wider system of gathering information, including digging pits to analyse the snow pack, taking detailed weather observations, and the continued use of all-important ski patrols.

''When we are expecting storm conditions, the ski patrol will have a team who will stay on the mountain overnight to monitor snowfall and the weather,'' Mr Howells explains.

''The other members of the ski patrol will typically leave town at around 5am and head up the mountain. On arrival, they will receive a briefing on the prevailing conditions and the main hazards from the overnight crew. When this is complete, they will fan out across the mountain to begin control work.

''In the early and mid-part of the snow season, the principal avalanche danger we're dealing with is what is known as wind-slab avalanche. These conditions are created by snowfall driven into stiff slabs by strong winds.''

Generally, control work involves using explosives to break up wind slab, Mr Howells says, adding the reliability and effectiveness of explosives has improved ''greatly'' over the past few years.

In spring, the main hazard is, typically, ''wet slide'' avalanches, created when the snowpack becomes either saturated with rain or heats rapidly as the result of solar radiation.

''Wet-slide conditions cannot be controlled in the same manner as wind-slab avalanches in that explosives are not very effective,'' Mr Howells says.

''Instead, the patrol relies on closely monitoring conditions and watching for signs that the snow pack may be losing cohesiveness and becoming unstable.

''If we receive 15-20cm of new snow, that does not necessarily lead to avalanche conditions. The conditions that may create avalanches are a combination of new snow and strong winds.

''It's important to realise that even when the skies clear and it stops snowing, strong winds can continue to transport snow and create avalanche hazard.''

Jumps, ramps, banks and boxes
As the popularity of freestyle skiing and boarding grows so, too, does the demand for variety and challenge in terrain parks. And that's where Heath Richmond comes in.

Having designed such parks at resorts in the United States, Mr Richmond has utilised a combination of computer-based analysis and personal experience in creating a new intermediate-level jump area at Cardona Alpine Resort's Playzone terrain park.

''Everything is measured and calculated; there is a reason for every distance and angle,'' Mr Richmond, explains.

''I used satellite information from Google Earth, then the land was surveyed and I also had a topographic map done. I put all that information into my computer to get an average and figure out what's there.''

Head of the parks team at Cardrona, Mr Richmond then used a 3-D computer-draughting program to design the new additions. As an example of the level of detail, he would select a date and calculate how shadows might cause issues within a landing area.

''You also have to factor in the fastest day of the year versus the slowest day of the year in terms of snow conditions, which are constantly changing.

''There's a lot that goes into it. Park design used to be done by feel, but we now take more of a scientific approach to it,'' Mr Richmond says, adding a background in carpentry also came in handy when building jumps, ramps, banks, boxes, rails and the various other aspects of terrain parks.

''You can do all that work, but then get to the site and discover one place is really hard and rocky or there is a stream that messes with drainage. You always have to have a backup plan and be able to think on your feet.

''All the jump lines get progressively bigger to help people progress. For instance, the first jump is easier than the third.

''As soon as we get enough snow, we will test it out. One of the guys in my team will be the first to hit the park to make sure it's safe. We'll do a lot of testing and tweaking before we open it to the public.''