Do you know time stacking?
This Technique is originally from astrophotography, but you can also use it in daylight. For example for a really cool effect with clouds:
For this picture I took around 100 exposures and stacked them together in Photoshop, using the masking by highlights to achieve this effekt.
It can also be used on windmills like this:
If you have questions how to do this exactly feel free to comment and ask me! :)