Relative humidity: The amount of water vapour present in the atmosphere at a given temperature expressed as a percentage of saturation at that temperature. Standard testing conditions for paper are 23 degress C and 50% r.h.

• 相对湿度:在某一温度下，空气中实有的水汽和同温度的空气在饱和时应有的水汽的比较，用百分率表示。测试纸张的标准环境是摄氏23度，相对温度50%25。