Refraction near the horizon—an empirical approach, case study 1: sunrise refractions observed at Edmonton, Alberta
Year: 2026
Type: supplementary-materials
Abstract: Variabilities of astronomical refractions, observed in near-horizontal directions, are reduced by converting them to a common atmospheric temperature gradient. It takes into account the nonlinear temperature gradient profiles near the Earth's surface which are logarithmic with height. The conversions are accomplished at altitudes -0.13°≤A≤0.24° and temperature gradients -7≤Τ'[K/km]≤168. 108 observed astronomical refractions, scattering originally by 4.6 arcminutes, are each converted to 24 ray tracing results -25≤Τ'[K/km]≤22, differing to them at their mean height HT ‘ MN = 140 m by 0.6 ±2.5 arcminutes. Converting the refractions to atmospheric median conditions result in an RSS reduction of -7% for pressures and temperatures, and in additional -39 % for temperature gradients. Wind acting as a partial pressure, reduces the variability by 2%, while total pressure increases it.
Source: Figshare
Author: Marcel Tschudin
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214967508