Sunny disposition

The weather responds to 4 year old Merryberry's emotions, but only her older sister, 7 year old Hollyberry realizes. When Merryberry's happy, the clouds disappear within a few hours. When she's unhappy, it is sure to rain.

For several weeks Merryberry's been sparkly happy and her life delightful. The problem is, everything is drying up. The plants are withering. The rivers are sludgy. Write about Hollyberry's comedy of errors quest to find a way to bring rain as she tries to avoid hurting her beloved little sister.