Rainbow Alan Dyer Image taken: Sep. 5, 2010 Location: near Cluny, Alberta, Canada Details: What a perfect rainbow this was! The Sun was just breaking through into some clear sky to the west, while rain was falling nearby to the east, the perfect combination of circumstances. The Sun was about to set, so the illumination is a warm red colour. The low angle of the Sun also means the rainbow appears as an almost perfect half-circle, rather than a chord. The centre of the bow lies opposite the Sun, here just below the horizon and at the point marked by the shadow of the photographer's head! The illumination was bright enough to create an outer secondary bow, with the order of colours reversed, caused by sunlight bouncing through an extra reflection in the raindrop before exiting the drop. Also note: - the bright region inside the inner bow created by additional light rays refracting out of the rain drops. - the dark area of sky, called Alexander's dark band, just outside the main bow created by a lack of refracted light between the two bows. - the so-called supernumerary arcs of repeating colours along the inside edge of the inner bow, and more prominent at the top than at the sides. - and extra brilliance of the red portion of the bow created by the red sunlight from the low Sun. - the converging of shadows toward the geometric centre of the bow. Technical: Taken with a Canon 7D camera at ISO 100 and a 10-22mm lens at 10mm, with the rainbow taken in two sections, left and right, and stitched together in Photoshop. © 2010 Alan Dyer ©2013, SpaceWeather.com -- This site is penned daily by Dr. Tony Phillips.