What is Dew?
The condensation of air vapour in the form of water droplets on cold objects is called as “dew”. It is a natural event that is mostly observed in spring and summer times.
Causes of Dew
Objects warming up during the daytime cool down at nights, and these objects also reduce the temperature of the air around them. Cold air can not keep water vapour up as it is the case with the hot air. Thus, excess of water vapour created in the cold air gets condensed on the nearest objects in the form of dewdrops.
Conditions for Dew
Dew formation depends on the following conditions:
- The humidity in the air should be above a certain value.
- The temperature of the air must fall to the degree called the dew point.
- The weather should be warm during the day and open and stagnant at night.
In windy nights, it will take longer to cool down to the dew point as the air will be in less contact with cold objects. The clouds reflect a part of the heat coming from the earth and prevent the objects from cooling down. For this reason, no dew is seen after windy or cloudy nights.