Condensation
Topic: Water in the Atmosphere: Humidity, Condensation, Clouds and Precipitation · NCERT: Class 11, Ch 10 "Water in the Atmosphere"; Class 11, Ch 12 "Water (Oceans)"
Meaning
Condensation is the change of water vapour into liquid water, or straight into ice. It happens when moist air cools to its dew point, the temperature at which it can hold no more vapour. It depends on how much the air cools and on its relative humidity. Air can cool by:
- rising;
- touching a cold surface;
- losing heat at night;
- mixing with colder air.
A fall in air temperature is the best condition for condensation. The vapour condenses on tiny particles called nuclei, and it releases latent heat. Condensation produces dew, frost, fog and clouds.
Example
On winter mornings in Punjab, drops of water cover the grass. Moist air touched the cold ground overnight, cooled to its dew point and condensed.
Don't confuse with
- Precipitation: condensation only forms droplets or ice crystals. Precipitation happens later, when these grow too heavy for the air to hold up and fall to the ground.