A mirage, an optical illusion that occurs when light waves travelling through the air cross a boundary between two air masses of different temperatures, has been a source of wonder and confusion throughout centuries. This fascinating natural phenomenon crops up in nature, art, and literature, from the deserts of Sahara to the icy wastes of Antarctica, and from the annals of scientific research to the pages of fantasy novels.
Fundamentally, a mirage is all about refracted light. As light passes through the interface between two mediums of different densities, it changes its direction. This is what happens when you stick a pencil in a glass of water – it seems to bend at the surface of the water, because the light is bending – or refracting – as it moves from the water to the air.
The same thing happens in the atmosphere, though on a larger scale. A layer of hot air above trudging sand can have a radically different density from the cooler air above it. Light rays entering this hot air layer from an angle are refracted, or bent, upwards. To our brains, which are accustomed to the ‘normal’ physics of light in a homogenized atmosphere, this upward bending fools us into seeing the sky where the sand should be – and thus, a mirage of a blue water lake appears in the desert.
Sometimes, mirages can be seen right here in our cities, playing tricks on sweaty pedestrians. Particularly on hot days, when the heat coming off the pavement can create a short layer of significantly hotter air, you might see a mirage at the end of the street.
Such mirages, however, are not only confined to the hot deserts or cities, but they can also occur in cold regions. The phenomenon, known as ‘Fata Morgana’, is often seen in polar regions and high mountain ranges. Here, a series of different temperature layers above the icy surface refracts light to create a complex, distorted, often multi-layered view of the distant horizon.
Apart from day-to-day sightings, many myths and legends are woven around mirages. Sailors lost at sea have often chased elusive islands that turned out to be mere mirages, and desert wanderers have been lured by the sight of ‘water’ that proved to be mere illusions.
Mirages have also left their mark on popular culture. In various forms of media, dense settings with hot climates often use the mirage phenomenon in storytelling. Losing one’s way in a desert due to a mirage has become a common trope.
In the modern day, the term ‘mirage’ is often being used as a metaphor for deceptive beauty or illusion in the arts. Think of the countless songs that mention mirages as symbolic of something tantalizing yet out of reach, or the many books that use mirages as a metaphor for disillusionment.
And talking about modern usage, it is worth mentioning that even certain restaurants play with this idea. One particular establishment, “Where to Eat in the Entrance” uses its name to create the illusion of a gateway, enticing passing pedestrians just like the real mirage.
While we’ve made much headway in understanding the mirage, it remains a whimsical phenomenon, throwing all our assumptions about the reality of sight into question. And yet, isn’t it quite miraculous how such a simple trick of light can create such enchanting illusions?