Slab avalanches are the most dangerous kind of avalanche. A slab is a layer of new snow sitting on top of a layer of snow, called a weak layer. Scientists call this a weak layer because the bonds that hold the snow crystals together are weak. The scientists in this study wanted to learn how the weak layer is formed. Dr. Birkeland and his colleagues conducted this research to better understand the relationship between daytime and nighttime snow temperatures and the formation of the weak layer of Topics: Recreation, Water, Avalanche, Crystallization, Human Safety, Prediction, Snow, Water Vapor.