Psychrometrics
Psychrometrics is the study of the thermodynamic properties of moist air — temperature, humidity, enthalpy and dew point. It underpins the design of HVAC, drying, and any process where air's moisture content matters.
Air is a mixture of dry air and water vapour, and many industrial processes depend on controlling that mixture. Psychrometrics relates dry-bulb and wet-bulb temperatures, relative and absolute humidity, dew point and enthalpy, usually visualised on a psychrometric chart. Engineers use it to size dehumidifiers and dryers, predict condensation risk, calculate cooling-coil loads and manage the energy in conditioning ventilation air.