The novel opens with an evocative, "big picture" description of the "Dust Bowl," the devastating drought conditions that characterized the Plain States in the 1930s. Steinbeck paints vivid word pictures of "the last rains" falling, in vain, upon the earth. Raindrops bounce off of dying corn. Stinging wind attacks the crops. Dust fills the air, even blotting out the stars at night. Farm women and children wonder if the harsh weather and the crop failures will cause their men's spirits and wills to break.
Throughout The Grapes of Wrath, Steinbeck alternates macrocosmic (or what might be called "big picture") chapters with microcosmic chapters that illustrate the effects of large scale social changes.
The novel begins by depicting the misery that was brought on by the drought that hit the Great Plains in the 1930's. This dust-blown landscape is the environment wherein the sharecroppers, including the Joads live.
Steinbeck describes in vivid detail the setting of the novel before introducing the characters. With this he emphasizes the importance of nature and how it can affect the lives of people and force them to become helpless victims.