Green Flash, Sun Pillar, Sundog, and 22-Degree Halo
The photo composition above shows examples of optical phenomena generated by sunlight. The first photo at the top left is a green flash on the upper edge of the Sun, taken from the beach of Marina di Pisa, Tuscany, Italy. At the top right is a sun pillar, that is, a column of light produced by suspended ice crystals that reflect the light of the Sun as if they were small mirrors. This photo was taken at the tower of Viterbo Airport. At bottom left is a classic sundog (left parhelion), also captured from Viterbo airport. Finally, at bottom right is a solar halo photographed above Ponte Sant'Angelo in Rome. The statues of angels are facing this halo, which lies 22-degrees from the Sun.
Related Links:
Halo Display Observed from Graubünden, SwitzerlandWhat Causes Halos, Sundogs and Sun Pillars?
Marco's Website