We define a “natural rainbow” here as any rainbow seen in sunlit raindrops.
W. J. Humphreys, Physics of the Air (Dover, New York, 1964; reprinting of 1940 edition), p. 476.
F. E. Volz, “Der Regenbogen” in Handbuch der Geophysik, F. Linke, F. Möller, eds. (Gebruder Borntraeger, Berlin, 1961), Vol. 8, pp. 943–1026.
R. A. R. Tricker, Introduction to Meteorological Optics (Elsevier, New York, 1970), pp. 169–190.
Aristotle, Meteorologica, translated by H. D. P. Lee (Harvard U. Press., Cambridge, Mass, 1952), Sec. III, paragraphs 372–375.
Seneca the Younger, Physical Science in the Time of Nero: Being a Translation of the Quaestiones Naturales of Seneca, translated by John Clark (Macmillan, London, 1910), p. 21.
J. M. Pernter, F. M. Exner, Meteorologische Optik (Wilhelm Braumüller, Vienna, 1922), pp. 565–588.
We distinguish between the rainbow’s observed colors (background included) and its intrinsic colors (background excluded). Also, we use luminance and brightness as synonyms in this paper, while recognizing that the two quantities are not linearly related (see, for example, Ref. 20, p. 495).
G. Wyszecki, W. S. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulae (Wiley, New York, 1982), p. 503.
We use the term clock angle to describe the angle that changes as we look around the bow at a fixed angular radius from the antisolar point.
G. P. Können, Polarized Light in Nature (Cambridge, U. Press., London, 1985), pp. 46–56.