Novaya Zemlya effect and sunsets

Abstract

Systematics of the Novaya Zemlya (NZ) effect are discussed in the context of sunsets. We distinguish full mirages, exhibiting oscillatory light paths and their onsets, the subcritical mirages. Ray-tracing examples and sequences of solar images are shown. We discuss two historical observations by Fridtjof Nansen and by Vivian Fuchs, and we report a recent South Pole observation of the NZ effect for the Moon.

Simulation of atmospheric phenomena

“…To insert them into the standard profile, thus altering it, we need a method suitable for ray tracing which also offers enough flexibility to tweak the parameters describing the layers. We use an analytical function known as the Fermi distribution, as proposed by van der Werf et al in [25] (see Eq. (13)):…”

“…What they saw was the Novaya-Zemlya mirage [25], which describes a case when celestial objects, such as the sun, can be seen even when they are situated below the horizon. The conditions for the effect differ from those of the superior mirage.…”

Chasing the green flash

“…We consider the properties of the atmosphere to be independent of x, since the changes in that coordinate are usually small and can be neglected. Considering a gradient also in that direction would enable us to simulate some other phenomena, like the Novaya Zemlya effect [van der Werf et al 2003]. …”

“…Any desired condition, though, can be reproduced if instead of taking the initial pressure and temperature values from the USA Standard Atmosphere we use the specific pressure and temperature conditions that lead to the phenomenon we want to reproduce, which can usually be found in the literature. In order to simulate the desired phenomena we need to modify this Standard Atmosphere, obtaining modified atmosphere profiles from initial parameters such as inversion layers [van der Werf et al 2003]. To achieve this, we have created an atmosphere profile manager, from where inversion layers can be appended to any given profile (usually the standard) by the following analytical function, known as the Fermi distribution:…”

“…As the system gets refined over time, we nevertheless plan to generate better images that mimic some more complex natural phenomena, such as ducting or the Novaya Zemlya effect [van der Werf et al 2003]. The green flash model obtained this far is purely academic, referred to by some authors as "the textbook green flash" [Young 2000].…”