Answer:
It means to disturb "the air." For example, the piercing cries is what the air is being disturbed by, so in general, it was silent when all of a sudden it has become disturbed or interrupted. I think this is a metaphor but I'm not sure.
*sorry if im wrong*
Answer: The trauma of the war caused his perspective to change.
Explanation: Before the war, Frederic Henry was very immature compared to Catherine, but after the war he had become very traumatized and he had matured to realize that war <em>is</em> a big deal.
I hope this helps!
