Shear instability in the atmosphere can result in a Kelvin Helmholtz wave cloud in the atmosphere that is similar to a breaking ocean wave. This photo was taken by George Arnott, brother of Pat Arnott, from his home in Pueblo CO around 1981. It is a posthumous memorial to his skill and insight as an amateur photographer. [amateur = one who cultivates any study or art, from taste or attachment, without pursuing it professionally.] This image has been published in the "Encyclopedia of Weather" and has been presented by Pat Arnott at an Optical Society of America Meeting, "Light and Color in the Open Air", February 1997, Santa Fe NM.