I've heard practically every theory regarding chem-trails but this is by far the worst! And don't even put me in the skeptic category. It makes no sense and nature would not EVER allow something like that to happen. Just look at the picture you used, by the way. It's evident that the so-called "half"-rainbow is on an arc with the fountain. This has nothing to do with chem-trails in the sky! It has everything to do with water from the fountain creating a mist mixed with sunlight! The same way ALL rainbows are made!