Pour into a three-liter jar of hot water (about 2, 5 cm.). Place on a baking sheet a few ice cubes and put it on the bank. The air inside the banks, rising up to become cool. It contained water vapor will condense, forming a cloud.
This experiment simulates the cloud formation during cooling of the warm air. And where does it rain? Turns, drops, warmed on the ground, climb up. There it gets cold, and they huddle together, forming clouds. Met together, they increase, become heavy and fall to the ground as rain.