Which of the following is NOT one of the three prerequisites for an avalanche?

• A. Unstable Snow
• B. Air Temperature Above Freezing
• C. Stored Elastic Energy to Propagate Fracture
• D. Snowpack Structure to Propagate

Answer: (B)

The key idea is that an avalanche requires three things in the snowpack: an unstable layer (a weak layer that can fail), a slab above that layer that can fracture and propagate, and enough stored energy to drive that fracture and release the mass. Air temperature above freezing isn’t itself a necessary condition for a release to occur; avalanches can happen in cold or warm conditions as long as those snowpack conditions and the stress in the slab are present. Temperature can influence stability by promoting melt-freeze cycles or weakening bonds, but it is not a direct prerequisite like the presence of a weak layer, a propagating slab, and stored energy.