Thunderstorm phenomena, illustration. Large thunderstorms, which form from a cloud type called cumulonimbus, produce a range of phenomena, including hailstones (top), rain (bottom), and lightning (cloud-to-cloud, cloud-to-ground, and ground-to-cloud). The lighting is due to electrical charge being redistributed (represented by positive and negative symbols). Hailstones form due to the storm's extreme updrafts of air (arrows) bringing water vapour to high altitudes where it freezes.