In the 1920s the American photographer Alfred Stieglitz, already famous for his city scenes and portraits, turned his camera upward. At his family's summer place at Lake George in New York he photographed clouds, and nothing else, for years.
His early sky pictures were grouped under musical titles, and a 1922 set was called Music: A Sequence of Ten Cloud Photographs. By the middle of the decade he was calling them Equivalents. He meant that each picture was an equivalent of an experience or an emotion, not a picture of a thing. People who saw the photographs could feel something without being told what they were looking at.
The pictures leave out the horizon. There is no ground, no tree, no person to give scale, only light and form in the frame. That made them feel abstract, and it let viewers turn them and see them from any side. Stieglitz wanted to show that the power of a photograph did not depend on a famous subject or a pretty scene.
The series ran, on and off, into the 1930s. It was a bold claim at a time when many doubted that photography could be art at all. If a photograph of nothing but a cloud could express the photographer's inner life, then the camera was more than a recording machine.
It is also an unusually good description of what a cloud reading is. The sky provides the shapes, and the person looking provides the feeling. A cloud is an equivalent, and the viewer decides what it is equivalent to.
