Around this time of year the tree colors become muted and grey, especially at twilight. The sky becomes a grayish orange, the colors of the environment fade. I've done many studies of this evening moment and this is my latest version done digitally on Photoshop. These are the trees I see out my window. Photoshop has got some great leaf-texture "brushes" and I'm using them here to my sketching advantage.
Photoshop, about 9" x 6", August 22, 2014.