Plane Contrail and Sun Halo

Explanation: What's happened to the sky? Several common features of the daytime sky are interacting in uncommon ways. First, well behind the silhouetted hills, is the typically bright Sun . In front of the Sun are thin clouds, possibly the home to a layer of hexagonal ice crystals that together are creating the 22 degree halo of light surrounding the Sun . The unusual bent line that crosses the image is a contrail -- a type of cloud created by a passing airplane. Much of the contrail must actually be further away than the thin cloud because it casts a shadow onto the cloud, giving an unusual three-dimensional quality to the featured image. The featured image was taken in late January in the city of Patras in West Greece .