Question

When the relative humidity is 90%, we say the air is: supercooled superheated saturated humid

Answer 1

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) = $\frac{P}{P_{vap}}$

where,            P = the partial pressure of water vapour

              $P_{vap}$ = the equilibrium vapor pressure at a particular temperature.

Accrding to the Clausius-Clapeyron equation, $P_{vap}$ 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, $P_{vap}$ will be high hence %RH will be low.

It is also known that at saturated condition, P = $P_{vap}$

Therefore, %RH is 100.

Thus, we can conclude that when the relative humidity is 90%, we say the air is humid.