How does the description of the color of the sky reflect how Tally is feeling at the beginning of the story?

The narration opens with a comparison of the summer sky at sunset to the color of cat vomit—an introduction to a central theme of the book: not all that is aesthetically pleasing is in fact truly beautiful. As night falls, Tally feels that the night is “bottomless and cold.” These observations serve as signifiers of Tally’s emotional state. Bereft of her best friend, she has become lonely, sad, and unsure of their connection.

it foreshadows the gloomy mood