Each labeled temperature will have one vertical line extending from the axis. If the measurement that you are looking for is between the labeled temperatures, estimate its location.
The humidity ratio is sometimes referred to as the “mixing ratio” or “absolute humidity. ”
The curved line gets its shape due to a rise in absolute humidity when the temperature increases.
Notice that as the temperature decreases, the relative humidity lines become closer together until they are nearly indistinguishable.
Since the lines for dew point remain constant and flat throughout the chart, the dew point does not change according to the dry bulb temperature.
Like dew point, vapor pressure remains constant even if the dry bulb temperature changes.
This measurement is helpful when using the chart to calculate the rate of cooling for a fan or coil.
As temperature and absolute humidity increase, the enthalpy also increases.
Normally, you should give preference to measurements of dry temperature, absolute humidity, dew point, or vapor pressure. However, you can also use relative humidity, enthalpy, and specific volume to make estimated conclusions.
For example, if you know the dry temperature and absolute humidity readings, you can use a ruler to gather information about the dew point, relative humidity, specific volume, enthalpy, and vapor pressure.
This is especially useful for visualizing how a change in temperature, absolute humidity, dew point, or vapor pressure affects relative humidity, enthalpy, or specific volume.
