Note: That the question states the air is saturated, meaning that, for a given temperature, air is holding the maximum amount of water vapour.

The capacity of air to hold water vapour is determined by its temperature. If the temperature is lowered => the air is capable of holding less water => some water will condense. However, Relative Humidity remains 100%.

• Water vapour depends on the amount of water the air is holding. As temperature is lowered, some water vapour will condense => Therefore, water vapour decreases.