Moisture (water vapor), cooling air (condensation) and condensation nuclei are all needed to form clouds. In this experiment, the lamp is our sun. The gallon jar with the water represents the ocean, with the empty space of the jar representing our atmosphere. The matches will make smoke, which serves as the condensation nuclei (dust, dirt, pollens, and pollutants). The condensation nuclei provide the surfaces on which water molecules can gather and condense into water droplets.
When the glove is pulled out of the jar, the air pressure is lowered inside the jar. The jar still has the same number of air molecules, but they now have more room and are less dense. The molecules collide with each other less frequently and slow down. This causes the air to cool. The smoke provides the condensation nuclei and a cloud is formed.