Fitzgerald uses specific colors to evoke different emotions. For example, green represents Gatsby's longing for Daisy and the American Dream, while gold symbolizes wealth and superficiality. The grayness of the Valley of Ashes reflects the bleakness and despair of the lower class.
The weather often mirrors the characters' emotions. Rain and storms signify turmoil and unhappiness, while sunshine highlights moments of joy and hope. The stifling heat of the summer emphasizes the characters' entrapment in their desires and illusions.
The lavish parties at Gatsby's mansion create a sense of excitement and extravagance, while the desolate landscape of the Valley of Ashes evokes despair and disillusionment.
Complete question
How does Fitzgerald develop mood throughout in The Great Gatsby?