An exclusive video series in which Christie’s specialists discuss the artworks, objects and artefacts that have truly made a difference. Here, photography specialist Laura Paterson introduces Clearing Winter Storm, Yosemite National Park by Ansel Adams, an artist she describes as ‘the most important name’ in 20th century landscape photography. This work and others by Ansel Adams are offered in our 20/21 Photographs Sale in New York on 31 March.