A local amateur astronomer has described the double rainbow spotted at Florida Lake recently as an “interesting phenomenon”.
Two days ago, as the storm was brewing just before dark, canoeist and safety officer of the Florida Lake Canoe Club (FLCC) and photographer member of the West Rand Photographic Society, Bertie Baard, took a shot of a double rainbow whilst attending a regular meeting at the boat clubhouse.
Local amateur astronomer, Kenny Nevill described the double rainbow as a “very interesting phenomenon” that is well deserving of an explanation.
“The second rainbow is in short a mirrored reflection in the nearby raindrops of the primary rainbow hence the fact that it is inverted.
“The photo (above) clearly shows the red colours being nearest to each other”.
He added that Wikipedia gives an excellent explanation: Secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and appear at an angle of 50–53°. As a result of the second reflection, the colours of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside. The secondary rainbow is fainter than the primary because more light escapes from two reflections compared to one and because the rainbow itself is spread over a greater area of the sky. The dark area of unlit sky lying between the primary and secondary bows is called Alexander’s band, after Alexander of Aphrodisiacs who first described it”.
