A low-lying rainbow due to the photo being taken around the middle of the day. Rainbows are nothing more than optical illusions caused by the diffraction of sunlight when passing through a rain drop. Assuming I also saw an observer underneath this rainbow, the said observer would be seeing a totally different rainbow and not a rainbow above him. The photo on the right shows an artificial rainbow created by a man-made fountain in the Upper Barracks, Valletta.