When in doubt, sound with an axe or stick and try to discover whether the snow is homogeneous, and if not, what lies below the surface layer and what lies below the snow itself.
When in doubt, turn back if possible. If it is necessary to proceed, take off your ski. If speed is important, keep on your ski; and if you are descending, put on sealskins. If you cannot spare the time to put on sealskins, sit on your ski and descend by a sitting ski-glissade, which is, by the way, a knack in itself.
The High Alps in Winter
Weather Conditions.
The weather after the New Year is usually more settled than in the summer. A spell of absolutely unbroken weather lasting from three weeks to a month or more is almost inevitable some time in January or February. As a rule, February is the finest month in the winter.
These typical fine-weather periods are often accompanied by mild weather. The temperature even by night is often surprisingly high on the glaciers, even when there is no touch of Föhn in the air. This has led some observers to claim that the temperature in winter—even in the shade—is often lower in the valleys than on the mountains. I have never seen any evidence produced for the phenomenon which has been romantically described as ‘inverted temperature,’ and have no reason to believe that any such violation of the laws of temperature really exists. It is often, of course, colder in the plains when the plains are covered by nebelmeer than in sunny alpine stations, but this is very different to any general inversion of temperature. I have, it is true, sat on the summit of the Finsteraarhorn in midwinter stripped to the waist, and I have often been uncomfortably hot at great altitudes in the sun. But it is dangerous to generalize from such experiences, and though on a windless day, winter mountaineering may be as warm and comfortable as summer climbing, the ski-runner must always be prepared for sudden danger of temperature, and severe cold.
The variations in temperature are surprising. A cushion of cold air, several degrees below freezing, may exist near the surface of the snow, and three feet above the surface of the snow the air may be quite mild. This is a phenomenon well known to rink-makers. In the sun the heat may be quite intense, and yet, a few yards off, in the shade the temperature may be several degrees below freezing.
A suspicion of wind may transform a mild and equable into an unpleasantly cold atmosphere. The changes of temperature are very sudden. You may be basking in shirt-sleeves on one side of a ridge, and be frost-bitten within a few minutes on turning a corner into the wind.
The great danger of winter mountaineering is the risk of a sudden change of weather. Storms seem to blow up out of clear skies with a suddenness to which summer affords no parallel. The man who is caught in a big winter storm is lucky if he escapes without casualty. A driving wind makes ski-ing almost impossible. The snow is blown into one’s face, and in a few minutes one’s eyelashes are gummed up with miniature icicles.
The big storms that sometimes prevail for more than a week at a time may imprison the climber in a club hut until all his provisions are exhausted. From most club huts escape is completely impossible till the storm drops. Even when the storm has given place to fine weather, retreat may be very dangerous owing to the avalanche peril.