As near as I can tell from the wikipedia link in the comments below, it's because the ship is perpendicular to the water and the light just happens to be being

As near as I can tell from the wikipedia link in the comments below, it's because the ship is perpendicular to the water and the light just happens to be being refracted to that particular observer right at the water line. [0] https://en.wikipedia.org/wiki/Fata_Morgana_(mirage)#/media/File:Fada_morgana_graphnn.JPG https://en.wikipedia.org/wiki/Fata_Morgana_(mirage)#/media/F...