Steinbeck was always about atmosphere: the atmosphere of the times as well as the atmosphere that specific characters must live through. Steinbeck is able to add texture to his story by including both. Note the sense of general despondence in the rural landscape in this quote,
In the last past of May the sky grew pale and the clouds that had hung in high puffs for so ... In the middle of that night the wind passed on and left the land quiet. Ch 1
We see this same sense of emptiness and despondence in specific characters as well later in the story when Ma Joad says,
"I never had my house pushed over," she said. "I never had my fambly stuck out on the road. I never had to sell – ever'thing – Here they come now." Ch. 6