The relative humidity is the amount of water vapor in air compared to the amount that it can normally hold. This quantity varies with temperature. A high temperature generally tends to hold more water vapor.
Given parameters:
Dry bulb reading = 18°C
Wet bulb reading = 14°C
Unknown:
Relative humidity = ?
To solve this, obtain the difference between the wet and dry bulb temperature;
Temperature difference = Dry bulb reading - Wet bulb reading
= 18°C - 14°C
= 4°C
Now we would compare this value with that of the relative humidity table.
The dry bulb and temperature reading should be traced for the point where they coincide, this will give the relative humidity = 65%
