>>517932Humidity is in the air. Humans emit moisture all the time via perspiration. This is why safety goggles fog up. An enclosed tent won't allow human-created humidity to leave. If the air outside is less humid than what you make it then you open the tent to let fresh, dryer air in. If it is more humid outside, you keep everything closed up.
To prevent humidity exchange during a rainstorm you'll need to water proof the tent walls. If you want to keep the floor dry in a normal tent, you can place an air mattress or foam under the tent and set the tent on top of it. That way the floor is raised up above any water/moisture problems. You can do a similar thing by mounding up sand under the tent.
