Dry air, an altitude of 1,822 m and about 322 days of sun a year. The phrase is a nineteenth-century advertising line, and it happens to be true.

In 1864, the hotelier Johannes Badrutt made a bet with four English summer guests: come back in winter, and if the weather is not better than London's, I will pay your trip. They came at Christmas, stayed until Easter, and winter tourism began.
Why the sky looks retouched
At this altitude there is less air above you and very little moisture in it, so less light is scattered. The sky turns a deep, almost navy blue, shadows are sharp, and the snow sparkles because the crystals stay dry and separate.

It also means the sun is strong. Wear sunscreen on the slopes even when it is minus fifteen, and drink more water than you think; the dry air takes it from you without you noticing.

