Rainbow formation: from Descartes to Venus

TL;DR

This paper analyzes the historical theories of rainbow formation, calculates rainbow parameters on Venus using geometric optics, and examines how sulfuric acid droplet concentration affects rainbow features, especially Alexander's dark band.

Contribution

It extends classical rainbow formation theories to Venus, providing new calculations of rainbow parameters considering sulfuric acid droplets and their concentration effects.

Findings

Concentration of sulfuric acid droplets significantly affects the size of Alexander's dark band.

Calculated angular dimensions of rainbows on Venus vary with droplet concentration.

The analysis bridges historical theories with planetary atmospheric phenomena.

Abstract

The mechanism of rainbow formation proposed by Descartes and Newton is analyzed. The parameters of rainbows on Venus are calculated using geometric optics. Assuming that solar radiation is refracted by spherical droplets of aqueous sulfuric acid solution, the angular dimensions of the primary and secondary rainbows are determined as functions of the solution's concentration. It is shown that changes in concentration have the greatest effect on the size of the Alexander's dark band, the angular distance between the primary and secondary rainbows.