With transparent water and glass a shadow is formed. The barrel shaped curvature of the glass and the surface of the water lead to many optical phenomenon at once: ray tracing, chromatic aberration, magnification, and imperfections in the glass from manufacturing can be seen in the pattern of refracted light. This picture was taken on my balcony; Monday, April 20, 2020 at 8:52 AM. Boulder, CO. Exposure:1/640 Focal Length: 70mm Aperture: f/5.6. By jiggling the table the observer can clearly see which rays are water related and which are glass.
—Benjamin L. Crane, NCAR, USA
01 Dec 2020