|Cosmic Pumpkin - Sunset at Alexandria, Egypt, March 18, '09 by Aymen Ibrahem (Night Sky over Egypt) of the Bibliotheca Alexandrina. ©Aymen Ibrahem, shown with permission.
Our curved atmosphere, denser at its base, acts lens-like to flatten the sun and moon as they set. Here the sun has yet to touch the Mediterranean but the flattening is already 23%, considerable for that effect unaided. The strong temperature gradients of an inversion are probably assisting by producing additional refraction. More extreme and they make this. The dark band cutting half way through the sun indicates warmed and dusty air inversion trapped beneath cooler and cleaner. Just a hint of green rim adorns the sun's upper edge.