What is dew?
Condensation of water droplets on the objects at the surface of the earth such as leaves and grasses are called as ‘Dew’.
When the atmospheric moisture is condensed and deposited in the form of water droplets on cooler surface of solid objects such as grass blades, leaves of plants and trees and stones, it is termed as dew.
What are the favourable conditions for dew formation?
Condensation in dew form occurs when there is clear sky, little or no wind, high relative humidity and cold long nights.
These conditions lead to greater terrestrial radiation and the solid objects become cold enough to bring the temperature of air down below dew point. In this process the extra moisture of the air gets deposited on these objects.
When dew is not formed?
Dew is not formed:
• on cloudy nights because cloudy nights are warmer than clear nights.
• in shady places because air cannot move there freely.
• on windy nights because wind carries away the moist air.
For the formation of dew , dew point should be above or below freezing point?
Dew is formed when dew point is above freezing point.
Give an example of dew formation from day to day life.
Dew formation can be seen if the water is poured into a glass from the bottle kept in a refrigerator. The outer cold surface of the glass brings the temperature of the air in contact with the surface down below dew point and extra moisture gets deposited on the outer wall of the glass.
PRACTICE QUESTIONS
QUES . Why are dewdrops not formed on a cloudy night? UPSC 2019
(a) Clouds absorb the radiation released from the Earth’s surface.
(b) Clouds reflect back the Earth’s radiation.
(c) The Earth’s surface would have low temperature on cloudy nights.
(d) Clouds deflect the blowing wind to ground level
(b) Clouds reflect back the Earth’s radiation.
