How does Lee use light and darkness to create the tone at the beginning of this chapter?

The walk back is even darker than before, and near the school, Scout remembers that she left her shoes backstage. She is thinking of returning to get them, when Jem stops her because he hears a strange noise. The darkness captures the evil and the unimaginable that is Bob Ewell. THere is a sense of foreboding as the children walk home.