Fig. 3. Representations of the polarized light field near midday at four wavelengths, obtained between 12:16 and 13:22h Eastern Daylight Time on 16 August 1999 (same data as illustrated in Fig.2). Each part of the figure represents the polarization pattern in the upper hemisphere of view at the wavelength indicated, as seen by an observer looking upwards (note that East and West are reversed from their locations on a standard compass because of this unusual direction of view). The outer circle represents the horizontal, with the inner circles representing elevations of 30° and 60°. The lighter inner region of the figure represents the theoretical location of Snell’s window (the angular extent of the sky above the water’s surface after refraction at the air/water interface), although this was not clearly seen at the measurement depth of 15m. At each location where the spectrum of partial linear polarization was measured and analyzed (as in Fig.1), the e-vector angle is indicated by the tilt of the line relative to a tangent to the circle passing through that point, and the percentage polarization is indicated by the thickness of the line (key provided at lower right). The approximate location of the sun midway through the measurement series is indicated by the sun symbol within Snell’s window.
