If you've ever looked up at the clouds and wondered where they came from, you're not alone. Atmospheric researcher Lubna Dada is fascinated by the mystery of how clouds form and what role they play in our climate. Today, host Aaron Scott talks to Dada about a recent study on the role of trees in cloud formation, and how this data will improve our current climate models. Want more stories on the environment or climate change? Email us at shortwave@npr.org.