Relative Humidity

Storage & Aging
Definition
The amount of water vapor in air expressed as a percentage of the maximum that air can hold at a given temperature. Abbreviated RH.
Why it matters
Because the maximum is temperature-dependent, the same water content reads as a different RH at different temperatures, which is why a humidor moved to a warm room appears to lose humidity.
In context
"At 70 degrees the gauge read 64 percent RH, right where he wanted it."