
Isabelle M. answered 03/30/19
Patient and Versatile Apple and Video Production Trainer
the name you are looking for is time-lapse photography. Depending on how fast the clouds are moving and what equipment you have, you can accomplish the same effect either way.
For very slow moving clouds, a time-lapse is probably more efficient. Some still camera have a setting to take a photo every x seconds
for faster moving clouds, speeding up footage would look smoother
Either will require the use of a tripod as the camera needs to stay in the exact same position for extended periods of time.
Good luck!