Years later, as I learned more about the dynamics of the atmosphere, I gained a much deeper appreciation for the complexity of the motion field associated with even so benign a weather situation as a field of fair-weather cumulus
on a summer afternoon.
I should have been suspicious, because there were some fair-weather cumulus
in the area that were beginning to show some vertical development.
And that's how I learned the practical difference between a fair-weather cumulus
and a storm cloud.