This is a Cirrocumulus setup with Cirrus spread. I decided to ditch the voronoi noise base as it was just too, well, noticeably voronoi, and presented a couple other issues. However I will attach a clip of the noise shader in a surface shader.
These setups used basic Perlin Billows to create the Cirrocumulus layer. The locations are based on the Cirrus density adjustment. Cirrus spread density is based on the Coverage Adjust in the the cloud layer.
As a note, Cirrus, and Cirrocumulus and subsequent mixes are high altitude cloud sets. These are based on clouds common here in Puget Sound region due to our convergence zone. North and South weather mixes in our region, as well as trade winds and weather from the west over the Pacific. It's sorta why our area is know for storms and rain.
