Rainbows Over the Italian Shoreline
July 05, 2021
Photographer: Kevin Saragozza
Summary Author: Marco Meniero, Cadan Cummings
Rainbows are undoubtedly one of the atmospheric events that most strikes the human imagination. This photo of a double rainbow rising out of the sea was taken in the Province of Syracuse in Italy. The optics of rainbows was first studied by the mathematician René Descartes in 1637. From his work in physics, he understood the mechanism of light passing through water and mathematically determined the angular position of the primary rainbow (about 42 degrees from the center point of the rainbow or the antisolar point). The physicist Isaac Newton further advanced the science thirty years later when he observed light is reflected at various angles based on the different wavelengths of the electromagnetic spectrum: red at 42 degrees and violet at 40 degrees from the center of the arc. Advancing our understanding of optics and the Earth’s atmosphere, we now understand that rainbows consist of an arc with the colors of the visible spectrum from red to violet. These colorful arcs occur 39 to 43 degrees from the antisolar point and are exactly opposite the position of the sun with regard to the viewer.
A product of both reflectance and refraction, rainbows are formed when sunlight passes through a water droplet and the light is refracted, reflected, and then refracted again- like a prism. If two reflections occur in the water droplet, a second symmetrical rainbow is formed with a radius varying from 50 to 57 degrees from the antisolar point.
Both the primary and secondary rainbow are clearly seen in this image. The image is very poetic and seems to recall the vision of navigators who went to sea following the atmospheric events without having the right scientific interpretation. Photo taken April 20, 2021.
Photo data: Canon EOS R, 1/30 second exposure, 16mm, f/8, ISO 800