Here, the sun is just about to rise over the Aleutians. Above the sun are noctilucent clouds, also known as polar mesospheric clouds. Noctilucent clouds appear 47 to 56 miles (75 to 90 kilometers) above the surface of the Earth, which is five to six times higher than the altitudes at which rainclouds form. See the orange line at the horizon on the left part of the photo? That's the layer in the atmosphere where rainclouds form, whereas the wispy blue stuff above the sun are noctilucent clouds.