Combining images for streaking cloud effect
...Later in the day I took a hike to a point I had never been to before. When I left the car there were no clouds, so I left my filter behind and just took a camera and tripod.
After spending some time at the point clouds formed and I wished I had carried my filter. I thought about it for a while and decided to take 40 images at 8 sec intervals, with the thought of combining them later. Here is the result...