Using near infrared (NIR) data from the VIRTIS instrument that once traveled aboard the Venus Express spacecraft, Kevin McGouldrick and Constantine C. C. Tsang found a periodic variation in radiance, most intense at the mid-latitudes. The paper is here.
What Did They Find?
They identified A 150-day periodic variation in radiance within the 1.74 µm and 2.30 µm windows, which is most pronounced between 30° and 60° latitude. They also found that in these mid-latitudes, radiance at these wavelengths steadily increased throughout the life of the instrument.
Why Is It Important?
The 150-day timescale is consistent with a model (developed by McGouldrick) of the Venusian condensational clouds vertical structure, driven by radiative-dynamical feedback. I'm not sure what that means, but thank goodness the paper is open source!
- McGouldrick, K., & Tsang, C. (2017). Discovery of a 150 day period in the Venus condensational clouds Icarus, 286, 118-133 DOI: 10.1016/j.icarus.2016.10.005