Question

When it is raining, the dew point is:
A.${0^0}C$
B.${60^0}C$
C.${100^0}C$
D.Room temperature

Answer 1

Since we have to find the dew point when it is raining, we know that the temperature up to which air should be cooled to become saturated is called the dew point. The water vapour will further condense to form liquid water or dew.

Complete answer:
The temperature at which air can hold exactly the amount of moisture present is called the dew point. That means it is the temperature at which dew forms. The condensation of water vapour again to form water is called dew. The atmosphere will hold the maximum amount of water when it is raining. Therefore we can say that when it is raining the dew point will be the room temperature.

Hence option (D) is the correct answer .

Additional information:
The higher values to dew point more the amount of water the atmosphere can hold. Cloud point is the equivalent term for dew point in liquids. As the temperature decreases the humidity of the air will increase. If the relative humidity increases the dew point will be near the current temperature of the atmosphere. The relative humidity will never exceed $100\%$, therefore the dew point temperature will never be greater than the temperature of the atmosphere. When the condensed water is suspended in the air it is called either fog or cloud.

Note:
If the temperature of the atmosphere is lower than the freezing point of water, then the dew point is called the frost point. Dew is formed by condensation while frost is formed by deposition. The dew point is measured with relation to humidity.