The middle bow, raked upwards more sharply than the inner primary and outer secondary, is a 'reflection rainbow'. A horizontal reflecting surface is need to produce it.
�There is a lake about two miles away - a weedy, shallow one more of a bird sanctuary than glittering water. But it does line up between the sun and the bow center.�
�There were [also] a lot of wet cobbles, wet pavements and puddles that might explain low parts of the reflection bow."
The reflecting surface need not be continuous. A number of small pools will suffice provided they collectively have sufficient area to reflect enough sunlight and are on the line joining the eye and the sun.
Upward going rays reflected from the watery mirror form the bow. Think of it as formed by a second sun shining from beneath the horizon. The bow centre directly opposite in the sky is then the same distance above the horizon as the centre of the ordinary primary and secondary bows is beneath it.
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