Ice storm is a destructive winter storm marked by the accumulation of ice from freezing rain. Freezing rain occurs when the air temperature above the ground exceeds 32 °F (0 °C), the freezing point of water. At the same time, the ground and the thin layer of air above it must be colder than 32 °F. Under these conditions, precipitation from a winter storm can form as snow in the freezing temperatures high in the clouds. The snow falls into the warmer air layer below. There, it melts into rain. Upon reaching ground level, the rain refreezes into ice. The resulting layer of ice can cover roads, trees, wires, and almost any other solid surface.
Freezing rain can form a slick glaze on solid surfaces. If freezing rain continues long enough, ice will build up until its weight causes damage. Such damage includes broken electrical wires, fallen branches, uprooted trees, and damaged buildings. Freezing rain may also create slick conditions on roads and airport runways. These conditions often lead to accidents. Severe ice storms have caused electric power outages lasting days or even weeks. Such outages can leave homes and businesses without heat in the winter cold.
