Condensation of Water

Rain starts as water vapor that has evaporated from the surface of the Earth. At higher altitudes the vapor condenses to form the cloud. An additional change in temperature or pressure causes the vapor to condense and fall as a droplet of water or rain. 
A simple experiment: 
With proper supervision bring a pan of water to boil on the stove. (Boiling is rapid evaporation.) Hold a glass of ice water well above the pan. (not too close or the steam can hurt) "Rain" should start forming on the glass.
This brings rain from the clouds.