Originally Posted by
cyccommute
I see your “yes and no” and raise you another one. Condensation is not totally “bad”. Yes, it is kind of a pain but condensing water releases heat as it condenses. In a small tent, that higher concentration of moisture means more heat is released as the water changes phase from vapor to liquid. The larger volume and surface area of a larger tent means less overall heat release.
We try to prevent condensation because we feel it makes us cold but that doesn’t fit with the thermodynamics. I’ve started many nights with the rain fly open to make the tent a bit more comfortable only to get up in the middle of the night to close the fly to retain heat.
The condensation occurs on the tent walls, where it is cold. It releases its heat into the tent wall (because it's cold). Most of that moisture came from the occupant's exhalations, which means that the heat being transferred is heat that the occupant has already lost. Sure, taken in isolation, that heat contributes a positive for the occupant, but really it is just part of the overall transfer of heat being lost outside through the tent walls.
Condensation really does make us cold, and it fits fine with thermodynamics. Primarily, liquid water defeats the effectiveness of the insulation around us, because heat conducts through water faster than it transfers through the air gaps in the loft of the insulation. (The effectiveness of insulation while wet varies depending on the material.) Secondly, water on skin conducts heat away from us faster because of the relatively high density and specific heat of water.