“You can roughly think of planetary climate as the surface temperature when the incoming energy from a star is balanced by the outgoing energy lost by the planet as heat,” planetary physicist Kaitlyn Loftus, who led a study recently submitted to Journal of Geophysical Research: Planets, told SYFY WIRE. “Clouds can both decrease the incoming energy (to cool a planet) and decrease the outgoing energy (to warm a planet) depending on their properties.” There have to be clouds before there is rain, and because they ultimately control climate, you need to understand them and how they function before you can make any predictions about the weather report on a distant exoplanet. Though there is only a small difference between incoming and outgoing energy on Earth, this can go to extremes in some more bizarre atmospheres. Exoplanet WASP-76 b only faces its star on one side. That side is scorching enough to vaporize iron that scientists believe is later blown over to the dark side, condensing into clouds that literally rain metal.