Mirages

Mirages (color insert, Figures 27a, b, c) are examples of atmospheric phenomena in which air [Page 556]refracts light enough essentially to produce reflections. Other refraction phenomena include the flattened sun (color insert, Figure 27d), the green flash (color insert, Figure 27e), the paper-lantern sun (color insert, Figure 27f), and twinkling of distant lights. These are all puzzling phenomena because they are different from what we know about reality: There is no water in the middle of the desert, the sun really is round rather than flattened, its light is white rather than green, and it is continuous rather than irregular or interrupted. Distant lights, such as stars, do not turn on and off. How could these phenomena happen? In this entry, refraction by air and ...