Moonrise at Selsey, UK June '05 imaged by Pete Lawrence.
©Pete Lawrence, shown with permission.
Layers of cool air trapped below warmer ones refract the light of the rising moon to make a weak mirage. The cooler layers are visible as dark bands crossing the disk. At top, dispersion creates a green rim. A more powerful mirage could have vertically magnified the rim into a green flash.
Pete Lawrence's Digital Sky