For the occurrence of a Fata Morgana a temperature distribution must be present, that may
cause both upper mirages and lower mirages, for example a strong temperature inversion
above a relatively warm sea surface. Above the sea the density upwards firstly increases
considerably and is then greatly reduced higher up.
This is moreover an unstable condition, so all sorts of changes take place in these layers and
deformations may occur in the image of the mirage. The objects often seem to be vertically
elongated. Hence a small object is observed as a column or a tower