Richard Hammond explores the science of weather by conducting a series of experiments to understand the physical properties of clouds, rain, and hail. By using a helicopter to collect cloud moisture and a high-speed cannon to test the impact of ice, he reveals the hidden mechanics behind these everyday atmospheric phenomena. The journey takes him from the wettest place in England to a research laboratory in Colorado, where he examines the layered structure of hailstones to determine why they are so destructive.