What is relative humidity (RH)?

Relative humidity (RH) is defined as the amount of moisture in the air compared to the maximum amount of moisture that air can hold at a specific temperature. This means it is expressed as a percentage, indicating how close the ambient conditions are to the saturation point where air can hold the most water vapor possible. For instance, if the relative humidity is 50%, the air is holding half of the moisture it could potentially hold at that temperature.

Understanding relative humidity is crucial, especially in coatings applications, as high moisture levels can affect the performance and curing of coatings, leading to defects such as improper adhesion or the formation of blisters. The other choices don’t accurately define relative humidity. The first choice pertains to electrical concepts, the third addresses the dew point, and the fourth relates to the characteristics of coating materials rather than moisture in the air.