Metaphor because the clouds and fog are being compared to a completely different thing: racial prejudice and misunderstanding.
Answer: Ponyboy is homesick
Explanation: At this point in the book, Ponyboy is at the church away from home. His feelings can be indicated by "I'm really home in bed, I thought." and ". . . like the usual weekend morning". He is reminiscing on his time at home, while in an unfamiliar situation (staying at the church).
