How does Fitzgerald use weather to reinforce the mood when Gatsby meets Daisy?

In Chapter five, Nick has "arranged" for Daisy to come to his house for tea, so that Gatsby can meet her. Gatsby is incredibly nervous. The weather -- on the appointed day, it is pouring rain -- is meant to suggest Gatsby's inner state, of course, but also the inappropriateness of the rain -- on this of all days -- underlines something about the unreality of Gatsby's dreams about Daisy, something that becomes more uncomfortably clear as the chapter continues and  Gatsby shows off his house to Daisy. Here are a few details:

• Nick's lawn: Gatsby is afraid Nick's lawn is not well-kept enough for Daisy. Even though it is pouring rain, he sends a man over to cut it. It is a bit absurd. Later, when asked about how the lawn looks, it is as if he had forgotten about the whole thing!


• When Daisy shows up, Gatsby, out of embarassment, has gone out the back door and pretends to arrive after Daisy does. When Nick opens the door to him, “Gatsby, pale as death, with his hands plunged like weights in his coat pockets, was standing in a puddle of water glaring tragically into my eyes.” 


• Nick so fed up with Gatsy's behavior he tells him he is acting like a child and goes outside and stands under a tree to be out of the rain. After half an hour, the sun comes out, and he goes back into the house to find Gatsby changed: “He literally glowed; without a word or a gesture of exultation a new well-being radiated from him and filled the little room.” 


• Later, when Gatsby is showing Daisy around his house, Daisy looks out the window: “Come here quick!” cried Daisy at the window. The rain was still falling, but the darkness had parted in the west, and there was a pink and golden billow of foamy clouds above the sea. “Look at that,” she whispered, and then after a moment: “I’d like to just get one of those pink clouds and put you in it and push you around.” 

We never find out what happens between Gatsby and Daisy while Nick is out in the rain. But Daisy's enthusiasm for the clouds is concurrent with the general feeling of irrational happiness at the end the chapter. The weather can be seen to represent Gatsby's mood (rain means sad, sun means happy), but in another sense the weather has nothing to do with how Gatsby feels, and its apparent "symbolic" value can be seen as another attempt to assign meaning to things that in themselves have no significance. Of course what Daisy says about the clouds makes no sense, but that doesn't matter to Gatsby. As Fitzgerald says of him, “No amount of fire or freshness can challenge what a man will store up in his ghostly heart.”