The Snow Should be Uniform.
But, whilst the ground itself should be varied, it is most desirable that the snow upon it should be of uniform quality throughout. Sudden changes, as, for example, when a thin crust will bear for some distance and then suddenly give way, are not only unpleasant, but sometimes positively dangerous. Perhaps the best of all snow is that which has rested for some time undisturbed at a temperature a few degrees below freezing point. Under such favourable conditions the tiny crystals of which it is composed settle down and pack together, forming a mass, the compactness of which increases with its depth. Nor does the surface remain unchanged, for here the dew condenses, and in freezing forms the innumerable thin leaf-like films above mentioned. The ski glide very easily over these, and sink into the compacter substratum just far enough to admit of easy steering.
Another capital snow condition is when a hard crust has been formed, on the top of which more snow falls to the depth of a few inches, the first few flakes of the new fall being wet, so as to adhere to the old crust and prevent slipping.
Wind-driven snow is not usually very good, but sometimes, if the temperature be not too low, it will form itself into a compact floury sort of substance, which will stick slightly to the ski to a degree just sufficient to help up-hill, but not enough to cause annoyance or to prevent a free passage downwards. Very hard snow is bad both for climbing and for glissading, for up-hill it becomes necessary to stamp vigorously in order to obtain a footing, and down-hill the lack of side grip renders steering very difficult. But quite watery snow, especially if it be shallow, often affords capital sport.
Sticky Snow.
The worst condition possible for ski-running is when, the temperature being slightly above freezing, the snow “balls.” This sometimes occurs with old snow when the sun is very hot, but much more frequently immediately after a fresh fall. The cause of balling is that water is formed on the surface, which, being pressed down into the colder substratum, re-freezes, and adheres to the bottom of the ski: to this, being again wetted, large clods of the “binding” snow readily attach themselves; sliding becomes out of the question, and one is obliged at every step to lift many pounds’ weight of mingled snow, water, and ice. Some partial cures for this evil exist, and will be found at the end of the book at page 105; but they are at the best but makeshifts, and to our minds ski-running in sticky snow is never really enjoyable. Fortunately, this state of affairs is not nearly so common as one might at first imagine, for after the snow has settled, even if the air be warm, the ski do not usually sink in sufficiently to reach the cold under-surface, and no re-freezing, the primary cause of sticking, takes place.
Crusted Snow.
Another kind of bad snow occurs after warm weather followed by frost, when an ice crust is formed. If sufficiently thick to bear, and if slightly warm, this is not so bad; but if it bears in some places and not in others a very irritating, and sometimes even dangerous, state of affairs exists. The evil is aggravated when the sun’s rays, penetrating, but not melting, the clear ice surface, are strong enough to reach the ground below. This being dark coloured, is warmed, and, of course, melts the snow which is close to it, forming large hollows, which, though capital hot-houses for plants, are veritable traps for the unwary ski-runner. On such a surface, when the crust is strong, the ski will slide rapidly, but when it is rotten they will break through, precipitating the runner forward, cutting his face and hands, and not improbably spraining his limbs and breaking his ski. Turning on such snow is a matter of extreme difficulty, for the pressure involved usually breaks the crust, with similar disastrous results. It behoves us to avoid such places, or, if we must cross them, to exercise extreme caution in doing so.
Patchy Snow.
A third, but less serious, sort of bad snow is commonly encountered, when the surface, being for the most part firm and in good order, becomes interrupted here and there by marble-like patches of very fine powder. This is a state of affairs which often occurs high up, when the cold is intense, and when strong winds blow fine snow over an otherwise good surface. The powder settles on the lee side of any inequalities and adheres to any slight irregularities. The ski glide very well over the old snow, but are checked by the powder, and a fall forward results. A little practice, however, soon enables one to distinguish between the semi-transparent, crystalline, darker-looking, old snow and the more opaque, white, fresh powder; and one learns how to make allowances by leaning backwards or forwards.