A humidification process in which liquid water is evaporated into the air with no external heat addition, causing the air to follow a constant wet-bulb temperature line on the psychrometric chart as dry-bulb temperature drops and humidity ratio rises. Evaporative coolers and ultrasonic humidifiers operate on this principle.
HVAC Glossary
Adiabatic Humidification
Last updated: June 9, 2026