As discussed elsewhere on this site, my PhD included a Doctoral Training year, which is similar to a Masters year, but focussed more on the skills I would need for a PhD.
As part of this year I did a summer project - basically a MSc dissertation - which was based around developing a Radiative Transfer Model that could simulate horizontally-hetereogeneous atmospheric conditions. This was then used to answer a question regarding the effect of isolated clouds in satellite images. It was hypothesised that the clouds would cause differences in surface solar irradiance (and therefore reflected intensity) a long way from the edge of the cloud. The report is available for download here.