Superior mirage distorting islands, page #1

The next eight pages show images of islands distorted by superior mirage. There is another set of subpages ('Isokari lighthouse and pilots' house distorted') with this kind of distortions.

On these pages images have been grouped in such a way that of a particular island different kinds of distortions are together; in some cases they are also compiled into composite images.

About superior mirages. A clear and 'good' superior mirage is far more rare than an inferior mirage. It may show up when a layer of cold air is covered by a warm layer (so called inversion layer). At my observing site this may happen in late spring - early summer, when the sea is freed from ice and warm and dry air is blown over the cold surface. This could create a steep thermal gradient (thermal gradient describes how temperature changes with respect to height), which is exactly what is necessary for a superior mirage to appear. Word 'superior' refers to the place of the mirage: miraging image appears above the 'true' object and is inverted. Large water surface appears bowl shaped (convex), horizon line extends abnormally far away and 'strange' new islands may become visible. Superior mirage is also responsible of the famous 'Fata Morgana'.

A good superior mirage is a lot harder to detect and to witness than the common inferior mirage. First of all you need a steep thermal gradient and also good visibility. My experience is that the best superior mirage is usually seen at the distance of 10-20 kms. Every so often a superior mirage is evident but due to haze or excessive humidity the contrast is poor and the sight is not too inspiring. This problem you can notice in several images on this page and also on other pages showing superior mirages. Moreover, film or chip does not reproduce good contrast through bluish haze. And even worse superior mirages are often short lived due to wind, which is born at shoreline and which very effectively mixes the inversion layer. One major obstacle in detecting superior mirage is also the height of the vantage point. A good display can be visible at certain height, while one meter higher or lower shows hardly any miraging. In general this means that to witness this phenomenon, you have to have access to different heights to view the horizon. A pair of binoculars is a must in the search of superior mirage.

Superior mirage is far more interesting than inferior mirage. Object may be just stretched or squeezed vertically or it may be doubled and turned upside down. In some occasions a second miraging image may become visible (this time right side up) above the first miraging image. In some rare cases two more miraging images can be seen above the first two - and here again the first image upside down and the second right side up.

It is worth emhasizing that all mirages affect also on radar in such a way that radar horizon may be closer than normally (inferior mirage) or horizon may extend a lot farther than normally (superior mirage).

For a more comprehensive approach to the subject see Andew T. Young's great pages.





















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Inferior mirage distorting islands page #4       Superior mirage distorting islands page #2

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