I enjoy using the NightCap app on my iPad. It has several time exposure settings for special night situations such as star trails, ISS passes, and meteors. It also has a light trails setting. One could set the iPad in a dark scene and move a flashlight around painting lines, figures, or words in the time exposure. I wondered if that setting would work in a bright blue sky scene with passing white cumulus clouds.
The iPad was propped up at about 45˚ and the exposure was started. This first photo was for 33 seconds. Notice the tree leaves at the left. They were moving with the breeze and were blurred. The clouds streaked during the exposure from lower left to upper right for a weird and pleasing effect.
More clouds drifted by in this 323 sec exposure. I think this experiment deserves more trials to see what other interesting effects it can produce. What do you think?