Have a hot lamp to act as the sun.
Use a rectangular fish tank with a slightly lower place or a small bowl inside as a lake.
Put on a transparent lid which would act like a cloud containing the evaporated water.
Make the lid slanted, without openings, with the higher side away from the bowl of water.
When you turn off the lamp, the water vapor will cool and fall back down.
You can make a slanted floor so the "rain" will flow back into the bowl.
