I never thought about it that way. I guess that is the difference between a poet’s thinking and an engineer’s.
Considering the idea that after a summer rain, the air smells of fresh earth, new mowed grass, with a slight ozone background, I guess “forgiveness” is an apt description.
It means that the earth washed away some of the pollution, there’s a rainbow and a reminder that the air could always smell as fresh if we could only clean up our act. Good point.