An ice storm is a kind of winter storm that is not a snowstorm or a rainstorm. Ice storms occur when there are three layers of air in the atmosphere. First, there's a top layer that is very cold. Here it starts to snow. Then the snow hits a layer of warmer air where it melts and turns into rain. Finally, there's a third layer of cold air near the ground. Because of this layer of cold air, the rain instantly turns to ice when it hits the ground