high thin clouds cause this one to have soft shadows and a coolish light key. sometime wish it was always sunny and cloudless but then i think, wow, that would get old after a while. the challenge is getting the overcast, milky, or downright gray days and making the painting believable. being true to temperatures in the color mixtures is the key. sensitivity to the chroma (saturation) is also key for nailing any lighting key. henry hensche and charles hawthorne from the cape cod school of art drilled this into their students. wish i had attended the school before it closed in the very early 90's. i had to get what i know about it from books and the internet.its cool that for a few weeks, i'm painting on the streets just yards sometimes from where they taught.