How is bright light defined?

I like the shadow test. If you put your hand 6” off the top of the plant at the brightest part of the day and see a strong shadow on the plant, that is bright light. Bright light should never be confused with the direct sun of a west-facing window, or the even stronger light provided by a south exposure (typically, the strongest light of the day). Always question whether a window: has awnings, has sheers or some other window treatment, receives shade from another structure or a tree (and does that tree lose its leaves in the winter?).