Let’s make the fog in the bottle.
At the moment when the rocket was driven, it becomes white in the PET bottle momentarily. It is because the temperature rapidly falls by the adiabatic expansion when an inside gas expands suddenly.
The fog can be made in the PET bottle in the classroom by using this experiment.
2 The small amount of water is put in the PET bottle, and rubber stopper is put. Put some air in the bottle by air pump.
The fog can be made and it becomes white inside the PET bottle after the rubber stopper is pushed away. If the smoke of the match is put inside the bottle before the pumping, it becomes easy to make the fog. It is quite the same mechanism that can make the cloud in the sky. During the pumping, the air temperature goes up.
After the stopper is pushed away, the adiabatic expansion occurs and the air temperature in the bottle is down. The fog is made.