Spring ski-ing is, as a rule, delightful. Snow is troublesome in the intermediate stage between powder and crust. Once a crust is formed, the more often that crust is remelted and refrozen the better, as there is nothing better than old crystalline snow which has been through the mill of melting and refreezing again and again. Unless wet Föhn blows such snow will always retain its crystalline character, even when remelted by the sun, and will always yield good ski-ing. Of course in the late spring at low altitudes the sun is powerful enough thoroughly to thaw and drench the snow, and in the middle of May below 7000 feet wet snow in the middle of the day is unpleasant. But in March and April ski-ing on melted crust is wholly delightful. Incidentally the best ‘Spring snow’ is often found at the end of or in the middle of February on southern slopes.
From the beginning of March onwards all slopes, save those at very high altitudes, begin to crust over. The process is gradual on northern slopes. There is a period when the northern slopes no longer hold the dry loose powder of winter but have not yet begun to crust.
Spring powder is common on north slopes in March. It is denser than winter powder, and is not so dry. It is slightly moist on the surface, and much heavier. It yields, however, a first-class running surface, and will take any turn or swing. Its main objection is the fact that it is peculiarly liable to avalanche.
Gradually, however, Spring powder disappears, save at great heights, and all slopes are covered by crust. In the afternoon the crust is melted, and the snow is soft and wet on all slopes. At night the snow is refrozen.
The normal cycle, then, of a normal spring (say April, at altitudes between 3000 and 9000 feet) is as follows: Hard crust at dawn; crust superficially softened between sunrise and midday; soft melted snow in the afternoon; soft breakable crust as the sun loses in strength; and solid hard crust after the sunset.
First let us consider the hard crust usually found at dawn.
This differs materially from the marble crust of winter, and from any of the crusts formed by wind action. It is, as a rule, slightly softer. What is more to the point, it is rougher. The surface of normal spring crust is perforated by numberless little holes. Sometimes these holes are quite small, mere pockmarks, sometimes they are as large as half-crown pieces. It is the presence of these holes and the roughness of the crust that makes steering easy, so that control is not difficult, and linked Christianias or Stemming turns are within the power of the good runner.
Perforated crust, in fact, is a delightful running surface. It is common at low altitudes in March, at moderate altitudes in April, and is normal in the High Alps in May, June, July and even August.
Film crust is found in May and June on the glaciers, and occasionally at low altitudes in April. It forms a delightful running surface. Unlike marble and perforated crust, it is not quite homogeneous. It is composed of a hard under-surface of solid crust, covered by a very thin, soft, and transparent film of ice, which glistens in the sun like burnished silver.
This film of soft ice is shorn away as the ski begin to come round on a turn. It provides a splendid purchase, preventing effectually all side-slip, and yet not sufficiently strong to make turns difficult.