Explanation:
The amount of moisture present in air at a given temperature is known as humidity.
Whereas relative humidity is the amount of percentage of moisture it contains when compared to the maximum moisture it can contain at a given temperature.
Also % Relative humidity (RH) = [tex]\frac{P}{P_{vap}}[/tex]
where, P = the partial pressure of water vapour
[tex]P_{vap}[/tex] = the equilibrium vapor pressure at a particular temperature.
Accrding to the Clausius-Clapeyron equation, [tex]P_{vap}[/tex] decreases with decrease in temperature.
Hence, it means that at super-cooled conditions the %RH would be 100%.
On the other hand, the temperature will be very high at super-heated conditions.
Hence, [tex]P_{vap}[/tex] will be high hence %RH will be low.
It is also known that at saturated condition, P = [tex]P_{vap}[/tex]
Therefore, %RH is 100.
Thus, we can conclude that when the relative humidity is 90%, we say the air is humid.
