To clarify: I understand that it's possible for only very high level clouds, like cirrus clouds, to exist at a location, and be considered "the lowest level cloud." However I am talking about the lowest level possible, not the lowest cloud that exists at a certain time.
Usually when we see low level clouds there's an amorphous, puffy top but always a very smooth, flat bottom section if the cloud is low enough. Below this "line" no clouds form, bar exceptional weather. My question is whether this "line" where cloud bottoms flatten fluctuates greatly from place to place and how to estimate it if it does fluctuate.
Thank you!