You start by noticing two parallel bows than curve upwards to to the right. These we see all the time. The brighter one (to the right) is the primary bow and the second one (to the left) is the weaker secondary bow. If you are very observant you will notice that the colors are reversed on them.

But there is another bow, considerably dimmer, that extends almost vertically from the primary bow, this is the unusual one.   And a nice example of something I have read about, but never seen personally, a reflection bow.  But what is it reflecting off?   Let’s figure this out!
[Triple Rainbow sur CliffMass]