But snow and pisting together make up a whole science, especially when a slope has to be maintained so that the surface lasts well for a whole day and several hundred runs. A quick course in snow and pisting now follows
Let's start from the beginning; what is snow?
To put it simply, snow is a drop of water that has frozen. We distinguish between natural and cannon snow. Natural snow falls as precipitation and cannon snow we make ourselves. Natural snow is usually much lighter, drier and more porous than cannon snow. Natural snow is often a clear, relatively large flake. Cannon snow consists of denser, rounder and more compact particles because it contains more water, at the same time as it does not have enough time to crystallise as much in the seconds it freezes before landing on the slope. This is why cannon snow lasts much longer than natural snow. It is also why we prefer to lay cannon snow directly on the slope in late autumn in order to achieve a durable foundation to build on. We make our own snow because the amount of natural snow that falls wouldn't be enough to make our slopes as well pisted as we want them to be. Without cannon snow the skiing season would be much shorter and there would be fewer pistes open.
Snow-making in three shifts
It is no exaggeration to say that we take making snow seriously. At our facilities in Sälen we have 33 people (2010/11) who work in shifts 24 hours a day to make snow. In Tandådalen, Hundfjället and Lindvallen we also have automatic systems which come on when it is cold enough. From the beginning of October we have people on site and Tandådalen is usually first out in Sälen. Tandådalen is also often one of the first ski resorts in the Nordic countries to open with a skiable piste at the end of October or start of November. The reason we say "usually" is because we depend on cold weather to be able to make cannon snow.
Water + pressurised air + cold = snow
Cannon snow is made from water and air with a snow cannon. Snow cannons can vary in appearance, but the principle is that pressurised air forces water through a nozzle and shoots out the water so that it is atomised. The small drops of water then freeze in the air before they land on the slope and create an artificial blanket of snow. We achieve the best effect from approx. -10°C, but we usually make snow as soon as the temperature dips below zero.
It takes a great deal of water to make snow. At full capacity we can force out over 33,500 litres of water every minute (2010/11). The reason why we lay snow slope by slope is simply due to the fact that the water and/or pressurised air is insufficient to do all the slopes simultaneously. As a result it can take several weeks before we have all our pistes ready. Read more about making snow here.
Pisting, the secret behind well-prepared slopes
Once the snow is laid, the second part of our work begins, which involves creating wonderful, skiable slopes, in other words pisting. Within the Sälen area we have 12 piste machines (2010/11) for preparing our slopes. The technical description for these is "tracked working machines with a large excavator blade on the front plus a milling cutter and a heavy rubber plate on the back". Or we could quite simply say that it is the piste machines which are the secret behind you being met by wonderful, well-prepared ski slopes every morning.
We piste all the slopes, every night
Operating a piste machine is not a game! It requires both expert knowledge and experience. The piste operator must be able to handle the machine's functions – the excavator blade alone has 16 pieces – as well as know the best way to lay the snow. We normally piste every slope every single day. Well every night to be exact. As soon as the last skier has left the slope the piste machines take over.
Skiing moves the snow downwards, but we move it back!
After a day's skiing, a slope needs to be pisted for several reasons. As every skier notices, the surface of the piste changes during the course of the day. What was a smooth piste in the morning is transformed into an uneven slope with hollows and mounds. After a few days we would have metre-high mounds and hollows down to the ground. In actual fact, we make moguls without doing anything at all! When hundreds, or thousands, of skiers make their way down the slope, hollows and mounds form where the skiers turn and swerve. In every cut, the ski digs up some of the snow surface and creates a small bank of snow. In a ridge the surface of the snow is planed down around half a metre a week by all skis. At the same time, all skiers move snow down the slope. So in order to move the snow up again, we piste from the valley up towards the peak.
Why we piste at night
Pisting takes place at night for two important reasons. Pisting during the day would involve a too high risk of accidents for our visiting skiers. Furthermore, the newly pisted snow surface is quite soft, as the machine mills up approx. 10 cm of the top layer of snow. And even if the heavy rubber plate compacts the snow, and gives it the characteristic ribbed stripes, the newly pisted surface would be ruined straight away during the day. In most cases the piste operators finish their task late at night and then the loose snow has 5-6 hours to freeze together and provide a lovely durable surface to ski on.
In our parks, however, we piste as late as possible. This means the snow does not have time to freeze, and we create somewhat softer landings for those who jump and do different tricks.
Longer lasting with ribbed stripes
The ribbed stripes that greet our early-bird skiers serve an important function. By "combing" the slope so that we create masses of small bumps, a greater surface is formed which the cold night air can cool the snow through than if we had simply made a uniformly smooth surface. The snow is more solid and lasts for longer. And when the first skiers cut off the frozen peaks, the loose snow travels down into the small "valleys" and provides a comfortable and attractive surface on which to ski. A uniformly smooth surface would also easily become icy and difficult to navigate.
Softer after snowfall
When it snows, the surface naturally becomes softer. It usually takes a few days before the snow is compacted and frozen together, and this depends on what type of snow has fallen to some extent. At the start of the season, a hard and wetter snow tends to fall. During the months of January, February and March, the natural snow is more often than not dry and porous before becoming more slushy again as spring approaches.
Welcome to Sälen and all the wonderful snow!
