Visual simulation of refraction phenomena in the Earth´s atmosphere

We present a simple method for visual simulation of refraction phenomena in the Earth´s atmosphere. The method divides the atmosphere into a set of spherical layers and the rays are approximated by circular arcs within the layers. The curvature of arcs is related to the variations of the refractive index. The path of the ray through the atmosphere is found by intersecting the circular arcs with the layers boundaries. The curved rays produce the shape and position distortions of the objects observed through the atmosphere. Depending on the type of distortion we distinguish a large variety of refractive phenomena such as mirages, omega sunsets, fata morgana, green flashes, etc. The described method has been embedded into the simple ray tracer and some images are shown to demonstrate our approach.