Fratercula arctica
primary and secondary bow
Secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and are centred on the sun itself. 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.
from Wikipedia
primary and secondary bow
Secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and are centred on the sun itself. 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.
from Wikipedia