Fata Morgana mirages also show alternating compressed and stretched zones. Rainbows and mirages are examples of optical phenomena. Some prefer glowing coals or shimmering mirages. Some UFOs which are seen on radar may also be due to Fata Morgana mirages. Refraction is also responsible for some natural optical phenomena including rainbows and mirages. Green flashes are enhanced by mirages, which increase refraction. They both began to see mirages, which were quickly followed by more vivid hallucinations. These kinds of inferior mirages are often called "desert mirages" or "highway mirages". The most commonly observed are sunset and sunrise mirages. Some common mirages are caused by a spatially varying refractive index of air. These are examples of so-called Arctic mirages, or "hillingar" in Icelandic. Despite their fighter cover fleeing, the two Mirages piloted by Major. Next were the two Gulf Mirages and the Gitanes Lola in tenth. Other famous observations that were called "mirages" may actually be referring to looming. He followed with "Radio Amor" (2003) and "Mirages" (2004).