Rays That Bounce and Bend

Since light is a visual phenomenon, its characteristics are more easily explained with photographs than with words. But in trying to take pictures of light, a peculiar problem presents itself: unless its energy is directed right at the eye or the camera, light is invisible. A man suspended in outer space, with the sun behind him, would see nothing; all would be blackness (save the distant planets and stars) because the energy of the sun would be streaming past him, with nothing to bounce it back to his eye. Standing on the earth's surface, however, he can see trees, houses–even the atmosphere–-all made visible by light bouncing off them and back to his eyes. This phenomenon is exploited in some of the photographs that follow. So that the bouncing and bending paths of different-colored beams of light can be traced, the air has been filled with smoke. The smoke particles help to catch the light and reflect it back toward the camera lens. Similar phenomenon often occur in nature: a beam of sunlight can be seen slanting through a room because it is glancing off dust particles in the air; the shaft of sunlight that are sometimes seen coming down through gaps in clouds are made visible by particles of haze or moisture present in the atmosphere.


Life Science Library - Light and Vision