Mirages in Canada make cities appear in the sky

When we talk about mirage, we immediately think to the deserts, and yet mirages also occur in frigid regions. Far from being hallucinations, mirages are very real optical phenomena since they can be photographed. On January 10, a meteorologist of Calgary, in the Canadian province of Alberta, was able to immortalize these apparitions with spectacular shots. Calgary’s buildings appear distorted, stretched upward: this is a superior mirage.

A temperature inversion that bends the light

These imaginary buildings in the sky actually stretch up to what is called in weather report, the “inversion layer”: the upper candling, or “cold candling”, occurs when theair near the ground is much colder than that present at altitude. In the case of the Calgary mirages, the difference between these two air masses was 15 ° C that day. A phenomenon called inversion because, in a classic weather context, the air is warmer on the ground and colder at altitude. The temperature inversions occur in mountainous areas, and more commonly in polar areas, above the land, pack ice or sea. In this situation, the light rays projected by real objects (buildings, boat, etc.) follow an ascending and curved path: the initial object is then deformed, stretched, and perceived as much larger. It sometimes appears offset from the actual object, and in some cases, reversed.

There are three categories of mirages altogether: the upper mirage of cold regions, the lower mirage of hot regions which makes an altitude object appear lower than reality, and Fata Morgana which combines several layers of reversals and gives appearances of superimposed objects.