Snow

• An avalanche is made of snow, but not all snow is created equal. Snow can be very moist and heavy or dry and light. After snow hits the ground and accumulates, its structure continues to change. Air temperature, ground temperature, humidity and wind all combine to modify the layers of snow. Sometimes the top layer will become very glassy and slick, and when a heavy storm dumps a lot of snow on top, the avalanche risk intensifies. In other cases, a layer near the bottom of the snow pack loses its cohesion, allowing the surface snow to slide away.