Horizon irregularity induced by turbulence

Abstract

At any instant the optical effects of atmospheric turbulence can result in a somewhat distorted image. As a consequence, the image of the horizon that ought to appear to be a smooth straight line may instead appear somewhat irregular. When we consider turbulence effects we call into question the idea that a small object that we expect to see just above the horizon will stand out (i..e., will be detectable) because it appears as a bump on what is otherwise a smooth straight horizon line. The degree of irregularity that turbulence may be expected to introduce in the image of the horizon is studied, and a theory that permits evaluation of the vertical irregularity as a function of horizontal extent is developed. It is concluded that for a sample case the effect is small but that, for an object close enough to the horizon line, the detection of this object could be interfered with by this effect.