The air in #4 is saturated, the
rates of evaporation and condensation are equal, and the relative
humidity is 100%.
OK we take off the cover and add water vapor to the air in #4 . This supersaturates the air, raises the relative humidity over 100%. This is shown in #5. With more water vapor, there will be more condensation. Note there are three arrows of condensation in #5 above and only 2 arrows of evaporation.
Since there is more condensation than evaporate the amount of water vapor in the air will decrease. It will eventually return to the situation in #4 where the amounts of evaporation and condensation are equal. The relative humidity will again be 100%
OK we take off the cover and add water vapor to the air in #4 . This supersaturates the air, raises the relative humidity over 100%. This is shown in #5. With more water vapor, there will be more condensation. Note there are three arrows of condensation in #5 above and only 2 arrows of evaporation.
Since there is more condensation than evaporate the amount of water vapor in the air will decrease. It will eventually return to the situation in #4 where the amounts of evaporation and condensation are equal. The relative humidity will again be 100%