Multiple rainbow at Loch Aline, Isle of Lewis


Figure 1


Figure 2

This multiple rainbow photograph, taken at Loch Aline, Isle of Lewis, on the Western Isles of Scotland at about 1300 utc on 18 December 2011, has captured a rare seven bows. (© Edward Graham.)

Figure 1 is the original photograph from the camera. Figure 2 is the same image, but digitally enhanced by increasing contrast and colour saturation to make the rainbows more clearly visible. The seven bows are: (1) primary, (2) secondary, (3) reflection primary, (4) reflected primary, (5) reflected secondary, (6) reflected reflection primary, and there is a very faint (7) reflected reflection secondary bow.

Sunlight reflected upwards from a smooth water surface before reaching the raindrops is responsible for the reflection bow (3). The photographer, Edward Graham, noted that there was only a thin layer of water on top of the frozen loch. This prevented waves from forming on the water surface despite a light to moderate breeze.

The reflected bows (4) and (5) are produced by sunlight reflected by the water after it has passed through raindrops. The reflection inverts the rainbow and the bow centre is then above the horizon. For the reflected-reflection bows (6) and (7) sunlight reflects upwards from the water, meets the raindrops and the resulting rainbow rays of light then reflect off the water to the observer.