ASC Avalanche Formation & Terrain Recognition 2 — Questions and Answers
Question 1: Which snow crystal type is most commonly associated with the formation of weak layers that lead to slab avalanches?
- Stellar dendrites
- Faceted crystals and depth hoar (Correct answer)
- Graupel
- Rounded grains
Correct answer: Faceted crystals and depth hoar
Faceted crystals and depth hoar form under strong temperature gradients, creating weak, sugary layers that fail easily under stress.
Question 2: What is the term for the temperature-driven metamorphism that converts snow into weak, angular crystals prone to avalanche formation?
- Equi-temperature metamorphism
- Kinetic growth metamorphism (Correct answer)
- Melt-freeze metamorphism
- Destructive metamorphism
Correct answer: Kinetic growth metamorphism
Kinetic growth metamorphism occurs when steep temperature gradients (>10°C/m) cause vapor to migrate and recrystallize into facets and depth hoar.
Question 3: A convex roll on a mountainside is considered a high-hazard terrain feature primarily because:
- Snow is always deeper there
- It creates a tension zone where slabs are most likely to fracture (Correct answer)
- Wind loading is never a factor on convex terrain
- It traps cold air that weakens the snowpack
Correct answer: It creates a tension zone where slabs are most likely to fracture
Convex rolls place the snowpack under tension, making them prime initiation zones where slab fractures commonly begin.
Question 4: During which phase of a storm cycle is avalanche danger typically at its highest?
- Just before snowfall begins
- During and immediately after heavy snowfall (Correct answer)
- Several days after the storm clears
- During cold, clear weather with no new snow
Correct answer: During and immediately after heavy snowfall
Loading rates during and right after heavy snowfall exceed the snowpack's ability to adjust, dramatically increasing instability.
Question 5: What is a 'solar aspect' and why does it matter for avalanche terrain assessment?
- Slope angle measured with a clinometer
- The compass direction a slope faces relative to the sun's path (Correct answer)
- The time of day when solar radiation peaks
- A type of radiation-caused surface crust
Correct answer: The compass direction a slope faces relative to the sun's path
Solar aspect determines how much direct sun a slope receives, affecting snow temperature, melt-freeze cycles, and the location of persistent weak layers.
Question 6: Which terrain trap significantly increases avalanche consequences even for small slides?
- Open bowls with gradual runout
- Cliff bands, creek beds, and gullies below the path (Correct answer)
- Ridgelines above the starting zone
- Dense forests with wide spacing
Correct answer: Cliff bands, creek beds, and gullies below the path
Terrain traps concentrate debris and burial depth; a small avalanche funneling into a cliff or creek bed can be fatal even when the slide itself is modest.
Question 7: A lee slope in avalanche terrain refers to a slope that:
- Faces into the prevailing wind
- Is sheltered from the wind and accumulates wind-deposited snow (Correct answer)
- Receives the most solar radiation during the day
- Has a history of wet avalanches only
Correct answer: Is sheltered from the wind and accumulates wind-deposited snow
Lee slopes are sheltered from prevailing winds and collect wind-transported snow, creating slabs that can be much denser and thicker than windward slopes.
ASC Avalanche Formation & Terrain Recognition 2
Which snow crystal type is most commonly associated with the formation of weak layers that lead to slab avalanches?