On the Horizon: Art and Atmosphere in the Nineteenth Century examines how artists and image makers incorporated new scientific and technological understandings of the atmosphere into their works and creative practices. Ideas about the airspace, both as a realm and as a physical frontier, signaled novel artistic possibilities. Suddenly, the atmosphere had a visual role to play in artworks––the aerial dimension came to be recognized as an essential and active pictorial element. To nineteenth-century artists, air offered a major representational challenge: How is it possible to portray something typically characterized by its transparency?