Mirages are defined as false images, or floating reflections of objects, near the horizon. Mirages are formed when light is refracted, or bent, as it passes through layers of air of different densities. This can occur when air near the ground is heated a great deal and at a constant rate. Deserts are the perfect environments for mirages. Mirages can also form when a layer of warm air covers a layer of cold air near the surface, like over an ocean.
Mirages come in a wide variety, from lakes to ships floating in the air.
Last but definitely not least on this list, is the green flash . The green flash is one of the more intriguing optical illusions. The green flash is visible just as the sun sets or as it rises and it only lasts for a short period of time. The longest green flash ever recorded was thirty-five minutes, but they can also be a short as a couple of seconds. The only time the green flash is visible is when most of the sun is below the horizon.