the illusion that deceives our eyes in summer

In the middle of summer. Consequently, on a bituminated road heated by the sun, it often happens to distinguish in the distance which looks like a water table. Similarly, Motorists. For example, cyclists experience it: it looks like a brilliant puddle just in front of them, but approaching, it disappears as if by magic. Nevertheless, This phenomenon has a name: Mirage.

A mirage is not a hallucination, but an optical effect. In addition, It occurs when the light we see undergoes a deviation by crossing layers of air at different temperatures. Furthermore, In summer, the Soleil heats it surface Road, which in turn warms the air just above. Moreover, Result: a very hot layer of air. therefore less dense, forms at ground level, while the air higher is cooler therefore dense.

Light moves to slightly different speeds depending on the air density. When it goes from a more dense layer of air to a warmer. less dense layer, it is gradually curved. This is called the refraction. On an overheated road, this curvature is important enough for light from the sky to be deflected towards our eyes.

Our brain then interprets these light rays as if they came from the ground. As the light transported is that of the sky. often blue or clear, we have the impression of seeing a reflective surface, similar to water. It is therefore not a puddle, but a piece of sky “projected” by road, according to the laws illusion deceives our eyes summer of optics.

This type of mirage is called a lower mirage. because the image seems to form under the real object (here, the sky). This phenomenon is very common in arid areas. on the asphalt roads in summer, or even above the dunes in the desert. Travelers on foot. cheval have often confused these reflections with real water points, which explains why the word “mirage” is associated with the idea of misleading illusion.

Mirages are not limited to summer roads. In the mountains. in sea or in polar regions, other types can be observed, such as the upper mirage, caused by inverted layers of air (hotter above, colder below). This type can give the illusion that boats or ribs float in the air.

In reality, seeing a mirage is proof that our eyes and our brain work perfectly … but that light physics does not follow the same path as our intuition. illusion deceives our eyes summer The phenomenon depends on different factors: soil temperature, the intensity of the solar radiationl’humidity air and even the color surface.

To see it easily, just roll on a road in the middle of summer afternoon and observe the horizon. The “puddles” appear and disappear as we advance, as if they retreated before us. This is the very signature of the mirage: an image that only exists in a precise position. disappearing as soon as we change the angle of view.