As a small child playing on a summer beach on the West Arm, it was a source of frustration for me that as the Sun moved into the west, it was often blocked by clouds that had grown on the ridges above me. Why did I often get shade just when I wanted to swim? The fact that I later understood the meteorology did not diminish the childhood disappointment.
The Kootenay-Lake Website offers a discussion and more pictures of the local cumulus clouds.
This is a view from beside the airport at Nelson of cumulus clouds growing over Mt. Nelson (Elephant Mountain) and the ridge above the North Shore.