Question 7.
Explain the following:
How can you relate the formation of water droplets on the outer surface of a bottle taken out of refrigerator with formation of dew?
Answer:
The water vapor of the air depends upon the specific temperature.
Dew point: An unsaturated air at a certain temperature is taken and its temperature is decreased, a temperature is reached at which the air becomes saturated with vapor. This temperature is called the dew point temperature.
Saturated with vapor: If the amount of air exceeds this limit, the excess vapor converts into water droplets. When the air contains maximum possible water vapor, it is said to be saturated with vapor at that temperature.
Now, if we take a water bottle out of a refrigerator, we will observe tiny water droplets on it:
(i) This means, due to decrease in temperature, the air cools.
(ii) It becomes saturated with water vapor.
(iii) As a result, the excess water vapor gets converted into tiny droplets.
(iv) The dew-point temperature is decided by the amount of vapor in the air.
