Air like all other gases has a certain capacity for taking up water vapour and this increases with rising temperature. At 100oC the amount of water vapour present in the space above freely evaporating liquid water is 100 per cent by volume, at 0oC it is practically nil. If the water content of the air at any temperature is lower than corresponds to saturation the air can take up the difference and can be used for drying.
The water content of the air expressed in g/cm3, is known as absolute humidity, and the ratio of the absolute humidity to the maximum amount of water vapour the air can take up at the temperature in question as ‘relative humidity’.
To be contd…………
