AGE 101 LECTURE SERIES
Condensation
This is the process by which water vapour becomes liquid (cloud droplets) or solid (ice crystals) on
cooling. The result of this process may be dew, fog or clouds. The moisture in the air though very
little but it is the most vital source of fresh water for living things. Condensation of water vapour to
form water droplets occur under very specific conditions. First, the air must be saturated. That is,
when the air is cooled to the dew point or when water vapour is added to the air. Secondly, there
must be particles or impurities around water vapour may condense. These particles are referred to
as condensation nuclei.
Condensation Nuclei
Presence of small solid particles provides the nuclei around which water vapour in normal saturated
air can condense. There are two types of condensation nuclei:
a) Hygroscopic Nuclei
These particles have a strong affinity for water vapour from which condensation begins before the
air becomes saturated. Substances such as sulphur dioxide and salt are classic examples of
hygroscopic nuclei. Large salt hygroscopic nuclei are normally confined to maritime regions near big
oceans. But the tiny particles called aitken nuclei can travel across continents and are found
everywhere, except the Polar Regions. Basically, the sources of these hygroscopic nuclei are sea
sprays, products of combustion and dust swept from the land by winds.
b) Non-hygroscopic Nuclei
These particles need some degree of super saturation of air depending on their size before attracting
any condensation. Classic examples include natural dust from land surfaces, human made smoke,
soot and ash.
Although condensation nuclei are essential for wide spread condensation of water vapour, only a
small fraction of the nuclei present in the air takes part in cloud droplet formation at any given time.
This is because other conditions must be fulfilled before precipitation can occur.
1
This study source was downloaded by 100000889810302 from CourseHero.com on 10-01-2025 12:52:02 GMT -05:00
https://www.coursehero.com/file/251788812/Condensation-LECTURE-SERIES-AGE-101-pages-1pdf/
Condensation
This is the process by which water vapour becomes liquid (cloud droplets) or solid (ice crystals) on
cooling. The result of this process may be dew, fog or clouds. The moisture in the air though very
little but it is the most vital source of fresh water for living things. Condensation of water vapour to
form water droplets occur under very specific conditions. First, the air must be saturated. That is,
when the air is cooled to the dew point or when water vapour is added to the air. Secondly, there
must be particles or impurities around water vapour may condense. These particles are referred to
as condensation nuclei.
Condensation Nuclei
Presence of small solid particles provides the nuclei around which water vapour in normal saturated
air can condense. There are two types of condensation nuclei:
a) Hygroscopic Nuclei
These particles have a strong affinity for water vapour from which condensation begins before the
air becomes saturated. Substances such as sulphur dioxide and salt are classic examples of
hygroscopic nuclei. Large salt hygroscopic nuclei are normally confined to maritime regions near big
oceans. But the tiny particles called aitken nuclei can travel across continents and are found
everywhere, except the Polar Regions. Basically, the sources of these hygroscopic nuclei are sea
sprays, products of combustion and dust swept from the land by winds.
b) Non-hygroscopic Nuclei
These particles need some degree of super saturation of air depending on their size before attracting
any condensation. Classic examples include natural dust from land surfaces, human made smoke,
soot and ash.
Although condensation nuclei are essential for wide spread condensation of water vapour, only a
small fraction of the nuclei present in the air takes part in cloud droplet formation at any given time.
This is because other conditions must be fulfilled before precipitation can occur.
1
This study source was downloaded by 100000889810302 from CourseHero.com on 10-01-2025 12:52:02 GMT -05:00
https://www.coursehero.com/file/251788812/Condensation-LECTURE-SERIES-AGE-101-pages-1pdf/
