Compare this photo to the previous post. The photos were taken about 30 minutes apart. Evaporation is taking place leaving clear patches in between the thicker cumulus clouds. So instead of a nearly continuous cloud layer we now have holes developing as drier air above the cloud area sinks through thinner portions of the cloud. Instead of stratocumulus the cloud type is now mainly cumulus. The next stage was the weakening of the upward motion that was making the cumulus clouds. After sunset the cumulus flattened into thin patches of stratocumulus.
The Weather Briefing Blog