For several weeks in the south of England, ships have appeared suspended in mid-air over the sea. It is a particular optical phenomenon, a real mirage, which is filling social media with photos. Many wonder if it is not photomontages, in reality there is a physical explanation that lies in the optics manuals and in special weather conditions that have occurred in Cornwall.
Superior mirage
According to the technicians, this is the so-called “superior mirage” due to weather conditions that determine the refraction of distant objects precisely in correspondence with the eyes of an observer. It is a phenomenon that often occurs in arctic regions, more rarely in lower latitudes. In winter, however, the opportunities for this type of phenomenon are more common. When a temperature inversion occurs, that is when the upper layers of the air are warmer than those below (a condition that usually favors the stagnation of fog) if suitable wind conditions are also found that prevent the haze to accumulate, when the light passes between the two layers that are at different temperatures (and therefore at different densities), it undergoes total reflection. A similar phenomenon occurs in a glass full of liquid with a teaspoon inside: if you look at a certain angle, the teaspoon seems to be broken in two.
Reflection of light
In the case of Cornwall, the denser very cold air bends light at such an angle that an observer on the coast is no longer able to accurately perceive the exact distance to an object in the distance. Sometimes an object that is below the horizon may even appear visible. On the other hand, the “inferior mirage” is what occurs in deserts or on a paved road in the middle of summer, giving the impression of being in front of an expanse of water. The phenomenon is the opposite: a layer of colder air on top of a layer of much warmer air in contact with the ground.
March 20, 2021 (change March 20, 2021 | 15:44)
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