Difference between the dry bulb and wet bulb reading ______
The greater the difference between the dry bulb reading and the wet bulb reading, the drier the air is. More evaporation occurs because the air is able to hold more moisture. When the air is totally saturated, no more water will evaporate and the dry and wet bulb readings will be the same.
These charts produced by University of Waterloo in Ontario, Canada were the best charts. I liked having students use charts. You will also find calculators and formulas that take into consideration air pressure. These charts give good results. The biggest mistake I see is people using a heat index chart which is a different concept.