I recently saw a Claude Lorrain (b.1600) drawing and painting exhibit at the San Francisco Legion of Honor museum. Beautiful, glowing ink washes of tree groves are my favorites. He also did a series of invented seaports. Some of the tonal wash drawings displayed churned up seas under the wrath of a stormy sky. Lorrain was a big influence on Turner. The digital sketch here, in progress is exploring high contrast, sunset lighting against a moody mid-ground. I hope to have a bit more free time to refine this concept more.

http://www.artcyclopedia.com/artists/claude_lorrain.html (links to Lorrain images) Check out the British Museum link. They loaned their work out of drawings to the SF show.