In the alternative energy video, "Kilowatt Ours", a resident of West Virginia laments the loss of a favorite mountain to mountain-top-removal coal mining. He recalls someone asking him if he had a picture of the mountain, and he replied that he did not, and for two reasons. First, it can be difficult to take a picture of a mountain since it is big and if you are close to or on it, how do you take a picture of it. Second, he lived on and around the mountain all his life, he never thought it would go anywhere, so why would he need to take a picture of it?
Similar difficulties face one wishing to take a photograph of the air. How do you take a picture of something that is all around you? Why would you take a picture of something that is ever-present?
Describing a hypothetical picture of air, one could mention it's oxygen content, temperature, water vapor content, water droplet density, carbon dioxide level, ozone concentration, particulate matter load, visibility or clarity, color, and the speed and direction of its movement. Some of these characteristics would show up in your image, some not, depending on their particular levels at the time.
How would you frame all of that?