A step in the bed surface is usually visible. Storm Snow - The snow that falls during a period of continuous or almost continuous snowfall. Many operations consider a storm to be over after a day with less than 1cm of snow. Surface Hoar - Crystals, often shaped like feathers, spikes or wedges, that grow upward from the snow surface when air just above the snow surface is cooled to the dew point. The winter equivalent of dew.
Surface hoar grows most often when the wind is calm or light on cold relatively clear nights.
These crystals can also grow during the day on shady slopes. Once buried, layers of surface hoar are slow to gain strength, sometimes persisting for a month or more as potential failure planes for slab avalanches. The temperature gradient is the change in temperature with depth in the snowpack. For example, if the temperature 20cm below the surface is 3 degrees warmer than the surface, then the temperature gradient in the top 20 cm averages 1.5 degrees per 10 cm. Gradients greater than 1 degree per 10 cm are often associated with faceting of crystals and weakening of layers, whereas lower gradients are usually associated with rounding of grains and strengthening of layers.