Humidity terminology: The difference between dry-bulb temperature and dew-point temperature is called what?

Introduction / Context:
Accurate HVAC diagnostics depend on clear temperature terminology. Dry-bulb, wet-bulb, and dew-point temperatures each describe different aspects of an air–water vapour mixture.

Given Data / Assumptions:

• T_DB = dry-bulb temperature (ordinary thermometer reading).
• T_WB = wet-bulb temperature (adiabatic saturation proxy).
• T_DP = dew-point temperature (onset of condensation).

Concept / Approach:
The “depression” relative to dew point is simply T_DB − T_DP, commonly called dew-point depression. It indicates how close the air is to saturation; smaller values signal higher moisture content and higher relative humidity.

Step-by-Step Solution:

Verification / Alternative check:
On a psychrometric chart, for a fixed DB, moving toward the saturation curve decreases DP depression; at saturation, DB = DP and the depression is zero.

Why Other Options Are Wrong:

Dry bulb depression usually describes thermometer shielding effects and is not a standard psychrometric term here.Wet bulb depression is DB − WB, not DB − DP.Degree of saturation and relative humidity are different measures, not simple temperature differences.

Common Pitfalls:
Confusing WB and DP differences; remember WB reflects adiabatic saturation while DP reflects actual vapour content relative to saturation at lower temperature.

Final Answer:

dew point depression