Air pollution remains a major environmental issue despite many years of study and much legislative control. In rec nt times, pollution on a global scale has become of particular concern. The gradually changing con- centration of trace gases in the global troposphere due to man's activity is becomming a matter of serious concern. No scientist would dare to pre- dict in detail the consequences of this gradual change due to its immense complexity involving social and economic factors and near countless chemical and phjsical cycles in our biosphere. In this chain of processes, the transport of...