Papa3 wrote:
A friend and I were driving back from the airport the other day. He
remarked, "Wow, cloudbase is high today. I bet it's at least 6,000
feet."

He and I began musing - exactly how do we know that cloudbase is high?
What visual cues tell us that the Cu are high (or low). We're not
talking Temperature Dewpoint spread here - strictly visual.

Any ideas?

I compare to nearby hills and mountains.

Of course, that doesn't work so well in the flatlands.

Jeremy