Interaction of upper westerly waves with intertropical convergence zone and their effect on the weather over Zambia during the rainy season

Intertropical convergence zone (ITCZ) is normally established over central Africa between 10 degree south and 20 degree South during southern hemispheric summer season and is the main feature of general circulation responsible for the rainfall over this region. The eastward mov'ing upper level troughs in the westerlies have a considerable influence on the systems in the lower level easterlies and thus directly or indirectly affect the rainfall patterns over the central Africa . In the present study the various types of interactions between upper westerly waves and inter tropical convergence zone that are noticed on examination of five year of syno ptic cha r ts have been discussed and illustrated by presenting typical case studies. A climatology of the movement and northwardexten sion of rhe westerly trough over the region is also presented.