Answer:
Water molecule is present in air these airborne water molecule are called water vapor, when the molecules are present in air they don't normally stick together as the space is too much.
Bill Nye took a giant bottle and covered it with a stopper and started pressurizing it with a pump to make the molecules come closer and become compressed also it increase the temperature even slightly and that warmth will cause the liquid stick with the smoke particles to go back to forming as vapor.
After that he removed the lid then the air inside the bottle is spread out and it will eventually cool also the kinetically energy is also reduced and that cooled air sticks with dust particle which now forms cloud.
This experiment shows how the clouds are formed and the science associated with it.
Without any photosynthesis, there would be no plants which would lead to the many of the civilians of Earth starving to death. In the likely scenario where photosynthesis does not occur the world would most likely go into an apocalyptic way with the human race as well as many other mammals dying. The organisms that would survive might be used as a food source but the population would drastically decrease