The arctic mirage is an atmospheric refraction phenomenon caused by a temperature inversion in the lower atmosphere. It is classified into three basic types, two of which (<i>hillingar</i> and <i>hafgerdingar</i> effects) occur fairly frequently. The third is the Novaya Zemlya effect, reported by polar explorers on several occasions as an anomalous sunrise during the polar winter, when the position of the sun was below the horizon. The Novaya Zemlya effect consists of the trapping of light rays beneath a thermocline of large horizontal extent. Within the thermocline layers, the coefficient of refraction must exceed 1, while above and below it the coefficient must be less than 1. Then certain upward rays repeatedly bounce back from the thermocline and are transmitted for long distances around the earth’s curvature. The anomalous sunrise is a special case of this generalized definition. The properties of the Novaya Zemlya effect, analyzed using a laterally uniform stratified-atmosphere model, agree with those reported by polar expeditions. A narrow strip or window appears near the horizon, with or without an image of the sun in the window. An observation sketched by Liljequist in Antarctica is reconstructed to demonstrate the model’s accuracy.
© 1979 Optical Society of AmericaPDF Article