A hailstone cut in half shows rings, rather like the rings inside an onion. Each ring records one journey through a storm cloud, where the stone met water that froze onto it at once or slowly. Smo ice bui when drop spread bef they fre, and clo ice ari when th freeze s fast th air is trapped inside. The number of rings tells you how often the stone was carried up again before it finally fell.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.