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Psychrometrics relation: dew-point vs wet-bulb as relative humidity decreases As the relative humidity of moist air decreases, how does the dew-point temperature compare to the wet-bulb temperature? Choose the correct relation.

Difficulty: Easy

Greater than the wet-bulb temperature
Equal to the wet-bulb temperature
Less than the wet-bulb temperature
Unrelated/independent of the wet-bulb temperature

Correct Answer: Less than the wet-bulb temperature

Explanation:

Given concept
For unsaturated air: T_dew ≤ T_wb ≤ T_db. As relative humidity (RH) drops, the mixture is further from saturation, so T_dew falls away from T_wb.

Reasoning
Lower RH → lower vapor partial pressure → lower T_dew. The wet-bulb temperature decreases too, but not as much; thus T_dew stays below T_wb.

Common pitfall
Confusing T_dew with T_wb; they are equal only at saturation (RH = 100%).

Psychrometrics relation: dew-point vs wet-bulb as relative humidity decreases As the relative humidity of moist air decreases, how does the dew-point temperature compare to the wet-bulb temperature? Choose the correct relation.

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