Ambient light from about 20-30 miles away casting an eerie glow on an eerier set of clouds. Too good to pass up an opportunity to photograph it.

Canon 17-50mm f/2.8 lens. ISO 400, 17mm, f/8 at 30 seconds. Edited in Photoshop.

Super late edit:

Forgot to add that after about five minutes out there, I started hearing a pack of coyotes howling on a hunt. (Yes, coyotes do hang out in packs sometimes). They were somewhere a couple of miles in front of me. In such flat country, on such a still night, no telling exactly how far away they were. I only knew they were far enough away to not present me any immediate danger. Made me smile listening to them do their thing.