How does Irene Nemirovsky use imagery in Suite Francaise?

Imagery:

"Beautiful fat pigeons cooed; swallows wheeled; sparrows hopped peacefully in the deserted streets. Along the Seine each poplar tree held a cluster of little brown birds who sang as loudly as they could. From deep beneath the ground came the muffled noise everyone had been waiting for, a sort of three-tone fanfare. The air raid was over...."

"The metallic shudder of falling iron shutters was the only sound to break the silence, a sound familiar to anyone who has woken in a city threatened by riot or war...."