A psychrometric chart is a graph that plots the relationships between various physical properties of air, including temperature, humidity, enthalpy, and specific volume. The chart is typically plotted on a rectangular coordinate system, with the dry-bulb temperature on the horizontal axis and the humidity ratio on the vertical axis.
Psychrometric Chart is a powerful graphical tool used by HVAC engineers and architects to visualize the thermodynamic properties of moist air and determine thermal comfort conditions. Originally developed by Willis Carrier in 1904, it allows users to plot two known air measurements to find all other environmental parameters—such as humidity and enthalpy—without manual calculations. Core Properties of the Chart psychrometric chart tutorial