A house in the archipelago with a superior mirage. If a steady temperature gradient exists, however, light will follow a curved path toward the cooler air. It is nevertheless also true that on the coast of the Gulf of Finland, a long-term current of warm air across the sea from Estonia may be just right for creating conditions which are conducive to mirages. The only explanation seemed to be some unknown force under the trackless waves, which had the power to shift all manner of marvels between the underwater world and the world above the surface!
People consequently tend to conclude that the mirage is a phenomenon produced by the delusions of a person who is exhausted by heat and thirst, a hallucination which exists only in the imagination of that person, rather than something which can be documented in, for instance, photographs.
In astronomy, this phenomenon is known as refraction: The entire shoreline takes on the shape of a rock wall where the familiar outlines are impossible to find; a mirage distorts the shores of Finland! In between, there is only water — or there ought to be only water. On the other hand, as the phenomenon occurs very frequently in late summer and early autumn, it is easy to see if you make a slight effort.
Imagine if you will that the denser air exerts a kind of friction on the ray of light, drawing it towards itself. The inferior mirage as a phenomenon is rather monotonous: In contrast, the formation of vertical layers of air with subsequent clear and stable horizontal mirages is not possible.
Therefore, when conditions seem favourable — for instance the first warm spring day by a cold sea — it is a good idea to scan the horizon from positions at different heights. Keeping in mind that light is refracted towards colder air, let us consider some of the peculiar things you might see out at sea, for instance. The ship turned up in a number of different shapes; sometimes there seemed to be two ships, one of the pair upside down.
Looking along the shore, you see distant islands, whose low, thin silhouettes grow into steep rock faces. Edwin Meyer, a physics professor at Baldwin-Wallace College, explains.
Only the sail is visible. This is called an inferior mirage. A sailing boat with a typical superior mirage in the background. If and when you come across this natural phenomenon, be grateful for the opportunity and make the most of the atmospheric optics!
Fortunately, warm spring air currents are often dry in Finland and thus offer good opportunities for looking for mirages. If you see this, it is well worth experimenting with different viewing heights to look for good mirages; it may even be worth waiting around for them.
An inferior mirage and the mirage of a ship. If the actual landscape itself is beautiful, then so is the mirage, and they may spread together across the horizon as a string of buildings and treetops. Mirages appeared seemingly at random, they might be visible only for a brief moment, they changed shape and disappeared as you approached them, observers at different heights saw different types of mirages, and so on.
In the past, seafarers who had visited all kinds of faraway places and seen all kinds of marvels usually developed something of a reputation as storytellers.
The vertical gradient produced by the sugar concentration will cause the beam to bend. Sign up for our email newsletter. A small boat with a superior mirage of islands.