These are straight vertical lines (or horizontal, depending on the chart's orientation). They represent the sensible heat level of the air—the heat you can feel.
This is the temperature at which the air becomes saturated (100% RH) if cooled at constant pressure. To find it, move horizontally left from your point to the saturation curve. psychrometric graph
Often described as a "graph of the physics of air," the psychrometric chart might look like a chaotic spiderweb of lines at first glance. However, once you learn its language, it becomes an indispensable map for controlling comfort, preserving food, drying paint, or even keeping a data center cool. Psychrometry is the study of the thermodynamic properties of gas-vapor mixtures—specifically, air and water vapor. The chart doesn't just plot temperature; it plots the relationship between heat, moisture, and energy. These are straight vertical lines (or horizontal, depending