Relative humidity Table (Whirling Psychrometer)

1: Dry bulb is ambient temperature.
2: Minus (subtract) wet bulb temperature from dry bulb temperature. Dry-bulb temp (20) - Wet-bulb temp (15) =  20 °C - 15 °C = 5  °C (value will always be positive +)

Result = RH 58 %

Relative humidity

Relative humidity is the amount of moisture in the air compared to what the air can "hold" at that temperature. When the air can't "hold" all the moisture, then it condenses as dew.

Relative Humidity (RH) =

(Actual Vapor Density) -------------------- (Saturation Vapor Density)

X 100%

Humidity affects the rate of evaporation. With a higher humidity, the rate of evaporation is less.

Terms:

Water Vapor  is the gas phase of water.

Condense is phase change of a gas to a liquid.

Saturated means reaching to maximum capacity.