Fata Morgana mirages
The optical illusion that makes objects hover above the horizon
The horizon is normally a reliable divider between sea and sky, but when atmospheric conditions are just right this boundary can seem blurred. Near the surface of the ocean, layers of air can form that are at different temperatures. Most of the air near Earth’s surface is warmed by radiation from the Sun, but a layer close to the ocean will remain cooler because the water chills it. As light travels from the warmer layer to the cooler layer it is bent downwards due to an increase in air density. Yet when the light hits our eyes our brains assume it has travelled in a straight line, so we perceive objects to be higher than they really are. This bizarre effect, known as Fata Morgana, makes objects appear to be floating on the horizon.