Using rainfall data for an evenly distributed number of rainfall stations in Transvaal, the Orange Free State and Natal, wet and dry periods were identified, during the summer months October to March, for the ten-year period 1980 to 1989. The main criterion used in the selection of these wet and dry spells was that they had lasted for at least five days. Altogether 19 wet and 17 dry spells were identified in this way, more than half lasted longer than five days. The factors which determine weather and climate are listed and discussed, with emphasis on South Africa. The main contents of this report are hemispheric charts of sea-surface and surface air temperatures and the ranges of these elements from summer to winter, as well as of the mean temperatures and heights of the 500 and 200 hPa surfaces in January and July.
Attention is drawn to the marked semi-annual wave of the pressure at middle and high latitudes.
Attention is also drawn to the Hadley and Ferrel cellular circulations as well as to the location of the ITCZ and the associated low-level circulation over southern Africa. This report describes the interrelations between pressure and wind phenomena, viz. In this publication selected topics on the characteristic properties of temperature in South Africa and the neighbouring territories are described. Brief mention is made of the research results obtained during the last decade on the relationships between fluctuations of sea-surface temperature and rainfall in South Africa. The most important documents, articles and dissertations on rainfall in relation to synoptic weather systems which appeared during the last 40 years are summarized.