Glacier Melt Bow   Imaged by Austin von der Hoya near Whittier, Alaska. Melt water from the Blackstone Glacier cascades into the sea raising enough spray to form a rainbow.   ©Austin von der Hoya, shown with permission.
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More about rainbows
                

The rainbow hugs the water because the sun was about 40° high. A rainbow's centre is always directly opposite the sun. As the sun rises the rainbow falls. Its radius is about 42° and when the sun is 40-42° high only the extreme rainbow top is above the horizon.

The requirement that the sun be lower than ~42° limits rainbow visibility. Rainbows rarer than we think and halos are visible more often. Rainbows are seen only a few times each year unless you live in the 'rainbow centres' of Hawaii, Ireland and Western Scotland.