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Show c. Every month from November through March recorded over 100 inches of snowfall in one year or another. Snowfall per month varies as much as 300$. Annual snowfall varies as much as 180$. d. Water content of snowfall per month varies as much as 300$; the average density of snowfall varies as much as 200$. e. Every month of the winter season has been free of dangerous avalanche action in one year or another. Conversely, every month has had two or more dangerous avalanche days in one year or another. For the avalanche observer, the significance of these comparisons is that each winter has its own individuality, that hazard fluctuates widely and rapidly from season to season, month to month, week to week, day to day, and even hour to hour. Any successful method of recognizing hazard must be equally flexible. CHAPTER 4. AVALANCHE CHARACTERISTICS CLASSIFICATION To the victim it makes little difference what kind of an avalanche caught him. But for purposes of records, study and analysis, some orderly method of classification is necessary. In this country, avalanches are classified first according to the type of snow involved; dry snow, damp and wet snow, slab snow and combinations. Second, they are classified as to the manner of release; direct action or delayed action, natural or artificial. Finally they are classified according to size, SIZE The dimensions of a slide would seem to be the logical method of determining its size. But to be of any value, the measurements should be accurate and these are often difficult, dangerous, even impossible to obtain. The shape of an avalanche is irregular. Wind action, sun action and snowfall quickly disguise it. Dimensions do not always indicate the momentum, one of the most important features of a slide. Whenever possible we record the dimensions of avalanches, for this information is certainly important. But our classification as to size is based on a different principle: the threat to life and property. This is our chief concern in avalanche study and therefore a logical approach. Large and major avalanches are highly dangerous to anyone or anything in their - 29 - |
