ENVIRSC 1A03 Chapter 8: UNIT 8 CLOUDS
25 Sep 2016
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Document Summary
Cloud droplets are made up of water droplets or ice particles. Formed by collision and bounding of water vapour molecules. Water vapour develops into droplets or particles which are 20 m (micrometers) to 50 m in diameter on average. The minimum temperature required for the formation is -12 c for water and -60 c for ice. Given their small size, the formation of droplets which would lead to the formation of clouds, would only occur under super saturation. Therefore, their small size requires a catalyst called the condensation nuclei. Which is a hygroscopic surface; on which water vapour can condense. Sea salt is the most frequent condensation nuclei at relative humidity"s less than 100%, the size of a water droplet depends on the relative humidity. When the relative humidity is slightly above 100%, the droplets can grow to sizes of several m to form fog and cloud droplets.
