Clouds

You can make your own clouds and see how they work. Just take a tea kettle and fill it full of water and put it on the stove to boil (make sure this is okay with your folks). When the steam comes out, it makes a white cloud - that's the water vapor with the sunlight (or artificial light) reflecting off it.

Get a tray full of ice cubes. Hold it over the steam, to see what happens when the steam gets cold. As the steam gets colder, the water vapor condenses into drops of water, and Earth's gravity pulls these to the ground as rain (you might want to put a cookie sheet under your rain so it won't get all over the stovetop).