Cloud and Rain Formation

Before we discuss the chemical composition of cloud and rain waters, it will be useful to assemble some background information on the processes leading to the formation of clouds and precipitation. The subject has been treated comprehensively in the books of Fletcher (1962), Mason (1971), and Pruppacher and Klett (1980), which should be consulted for further details. 

Another important aspect of cloud formation is the generation of ice particles at temperatures below the freezing point of water. The spontaneous glaciation of liquid water drops in clouds is a fairly rare event unless the 

According to data assembled by Mason (1971) and Pruppacher and Klett (1980). 

Two mechanisms are thought to be operative in the formation of rain the Wegener-Bergeron-Findeisen process, and the warm rain process. The first of these is germane to high-reaching continental clouds and starts with the growth of ice particles in the upper part of the cloud. Under favorable 

For global considerations of cloud chemistry, it would be desirable to have data on the spatial distribution and the average lifetime of clouds in the troposphere. Such data, unfortunately, are not generally available. De Bary and Moller (1960) have evaluated aircraft observations of cloud coverage over Germany to derive frequency distributions of clouds with height. Their results suggest that at midlatitudes the clouds are concentrated 

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