A Rainbow after Sunset

Abstract

ON the evening of August 29 the almanac sunset for Ireland south is placed at 6h. 51m. Happening to look out to south-south-east I saw a well-marked, though not very brilliant, portion of a rainbow in a shower cloud just above the horizon. It was not a perfect bow, but what sailors call a dog. I looked at the clock and saw that it was 7.15 p.m. Knowing that the sun had set, and being curious to see what could have produced the bow, I immediately went out and examined the western sky. The sun had indeed set, but there was a bright red glow and some flocculent clouds were tinged strongly with a brilliant rosy red. It was plain that the rainbow was caused by reflected light.