Psychrometric: Graph

Once you learn to see the air through these lines, you will never look at a cloudy window or a sweat glass of iced tea the same way again. You are seeing psychrometrics in action. Standard psychrometric charts are published by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) and are available for various altitudes.

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. psychrometric graph

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. Once you learn to see the air through

Air is invisible. Yet, for heating, ventilation, and air conditioning (HVAC) engineers, it is a complex mixture of gases, water vapor, and energy. To visualize this invisible world, engineers rely on one of the most elegant and powerful tools ever developed: The Psychrometric Chart . These are straight vertical lines (or horizontal, depending

These are straight horizontal lines measuring the actual mass of water vapor per mass of dry air (grains/lb or g/kg). This tells you how much moisture is in the air.