Ion clusters and the Venus ultraviolet haze layer

The daytime ionosphere of Venus is observed between 100 and 500 km altitude with a peak electron concentration of 100,000/cc at 140 km. It is suggested that at altitudes less than 130 km the ion CO2(+)-CO2 is an important ionic constituent of the Venus ionosphere. Below 100 km ion clustering processes combine with the low temperature at the mesopause to form coagulates, giving rise to the ultraviolet haze layer observed. An atmospheric model is presented.