Avalanche Formation & Terrain Recognition Flashcards
7 cards from real ASC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Avalanche Formation & Terrain Recognition flashcards as text
Why are north-facing slopes (in the Northern Hemisphere) considered more prone to persistent weak layers?
Answer: They remain cold and shaded, allowing faceted crystals and depth hoar to persist longer
North-facing slopes stay cold throughout winter, promoting the temperature gradients needed for facet and depth hoar formation while preventing melt-stabilization.
What is the significance of a 'crown' in an avalanche path?
Answer: The fracture line at the top of the starting zone where a slab broke away
The crown is the sharp, vertical wall at the top of an avalanche's starting zone, marking where the slab fractured from the surrounding snowpack.
Which terrain feature is considered an 'avalanche path island of safety'?
Answer: Dense forest or ridgeline that is demonstrably out of reach of avalanche debris
Dense, old forest or a protective ridgeline that avalanche debris cannot reach offers genuine refuge from avalanche hazard.
Graupel in the snowpack can act as a weak layer because:
Answer: Its round, pellet-like shape prevents bonding with surrounding snow grains
Graupel pellets are spherical and poorly bonded to adjacent layers, creating a ball-bearing effect that can serve as a failure plane for overlying slabs.
How does forest cover affect avalanche hazard on a slope?
Answer: Dense forest anchors snow and reduces avalanche initiation, but thin or damaged forest offers little protection
Dense, mature forest anchors the snowpack and disrupts slab formation, but open or thinned forest provides little protection and avalanches can still form and run through trees.
When assessing an unfamiliar slope for avalanche hazard, which factor should be evaluated FIRST?
Answer: Slope angle, aspect, and elevation in relation to the current avalanche forecast
Slope angle, aspect, and elevation are the fundamental terrain filters that align with avalanche forecast problem types and danger ratings.
What distinguishes a 'storm slab' problem from a 'wind slab' problem in avalanche forecasting?
Answer: Storm slabs form from widespread new snow loading, while wind slabs form in localized lee terrain features from wind transport
Storm slabs develop across broad areas from recent snowfall loading, while wind slabs are localized to lee slopes and terrain features where wind deposits transported snow.