Helen and I were at a place called 'Symonds Yat' today - a high vantage point over a large bow in the river Wye on the border between South Wales and England.
There was an exquisit layer of fog across the whole of the valley below, for dozens of miles around.
At one point, I could cast my shadow onto the fog below, and around me, was a small rainbow. The pictures don't really do it justice, so I stretched one a little to show the effect but it was quite astonishing!
Doug