Photographers were waiting for the threatening skies to open up. Some left. Finally, a glorious and dramatic sunset emerged. Taken at the Oxbow viewpoint in Grand teton National Park, I highlighted the upper thirds of the photo to underscore the drama of the sky. I used a Nikon D 7100, Nikkor Zoom Lens (18-200 mm.), with a Lee .9 Soft Graduated Neutral Density Filter. The ISO was 200, F/16, 1/5th second exposure, and a Focal Length of 35 mm.