Head in the Clouds - Owain Wyn Evans, Gavin Pretor-Pinney, Amanda Maycock

The episode examines clouds as both evocative features of the sky and central components of Earth's atmospheric system. Guests discuss their formation, visual variety, cultural resonance, and influence on climate, drawing from personal observation, historical classification, and modeling challenges. The conversation moves from individual appreciation of specific cloud types to the physical processes that create them and the uncertainties they introduce in climate projections.

Cloud appreciation and classification

Gavin Pretor-Pinney describes founding the Cloud Appreciation Society to counter the tendency to view clouds mainly as obstacles to sunshine. The society promotes recognition of clouds as dynamic, visible expressions of atmospheric motion. Classification began in 1802 with Luke Howard, who assigned Latin names such as cumulus, cirrus, and stratus based on appearance. These ten basic genera remain in use, supplemented by roughly seventy additional features and species that capture details like wave-like edges or localized curls. Cumulus clouds receive particular attention for their well-defined, seemingly solid shapes, which arise from sharp boundaries in temperature and moisture between the cloud and surrounding air. The base marks the level of saturation, while the top often borders drier air, producing crisp outlines despite continuous internal evaporation and