How does Steinbeck create an ominous atmosphere in Chapter 2?

In Chapter Two, Steinbeck introduces the main characters who work and live on the ranch. Not only are characters introduced but also three of the important conflicts which threaten both George's and Lennie's friendship and George's dream of owning his own farm. The first event which portends later complications is when George and Lennie see the boss. Rather than remembering to keep quiet, Lennie repeats George's words about being "strong as a bull" and causes the boss to become suspicious of George:

"Now he's got his eyes on us. Now we go to be careful and not make no slips. You keep your big flapper shut after this." He fell morosely silent.

George's morose silence is a sign of his growing discontent with Lennie, who always seems to act inappropriately at the wrong time.
Second, Curley's appearance in the bunkhouse foreshadows the events in Chapter Three. He immediately seems to take a disliking to Lennie, sizing him up and insisting that he speak:

He glanced coldly at George and Lennie. His arms gradually bent at the elbows at the elbows and his hands closed into fists. He stiffened and went into a slight crouch. His glance was at once calculating and pugnacious. Lennie squirmed under the look and shifted his feet nervously..."By Christ, he's gotta talk when he's spoke to."

Later, Candy claims that Curley is often out to fight a bigger man in order to prove his mettle. Therefore, he proves an ominous threat to George's hopes that he and Lennie can "roll up a stake" for their future farm.
Finally, the intrusion of Curley's wife into the bunkhouse is another threat to George and Lennie. Lennie has a history of being fascinated with soft hair and fabric, and Curley's wife's appearance in the bunkhouse again seems to pique Lennie's interest. After George violently admonishes Lennie for looking at Curley's wife, the big man expresses his fears about working on the ranch and even tells George that they should leave:

Lennie cried out suddenly—"I don' like this place, George. This ain't no good place. I wanna get outa here."

George argues that they need the money and must stay. In retrospect, this is a mistake and these threats materialize into trouble in proceeding chapters.