Photo is taken as the rain just started so that the colored pattern done by kids on sunday is still visible. As the rain keeps falling, colors left by chalk are gone, left only on photos..
And I like how the rain, enhances colors of greens and flowers- that is a basic idea behind this.
Your description reminds me of the scene in Mary Poppins after Bert, Mary and the children spend a day playing in the chalk drawings. It ends with a rain shower and the pictures start to wash away. Good shot.
