Rainbow Formation in the Venusian Atmosphere

The possibility of rainbow formation in the Venusian atmosphere is discussed. The Venusian clouds contain liquid droplets of aqueous solution of sulfuric acid of 75% concentration by weight having a mean refractive index of 1.437. From the theory of rainbow formation, we find that the primary and secondary bows on Venus would be formed at angles of 29.1 o and 74.9 o respectively from the anti-solar point. Thus the primary Venusian bow would be much smaller and lower in the horizon than the primary terrestrial bow while the secondary Venusian bow would be much larger and higher up in the sky as compared with its terrestrial counterpart. The intensity of a bow depends upon the intensity of sunlight and droplet size. From the estimated diameters of the droplets in the lower Venusian clouds and the distances of the two planets from the Sun, it is estimated that the Venusian bow would be only one-third as bright as the terrestrial bow. However, since the Venusian clouds are much stabler, one would expect the Venusian bows to be much more persistent.