Though Indonesia is counted as belonging to the “monsoonal tropics”, the monsoons are not so typical for its climates as for the borderlands of the Asiatic continent. Little is noticed of the monsoon in Sumatra where a daily alternation of land- and seabreezes is strongly developed. The island of Borneo has an equatorial raintype with daily rains all through the year and only small contrasts between luff and leesides of the mountain chains. It is on the island of Java that the transition from the equatorial to the monsoon type takes place. Moving from West to East, a more developed dry season is noticeable in the socalled East monsoon, which is, in fact, the SE trade wind reinforced by the relatively high pressure area inside Australia. The nearer the location to Australia, the less vapour it has accumulated on its shorter trip and the less precipitation it brings to the islands of Insulinde. The small Sunda-islands represent this type of climate where in some places (Waingapu, Sumba) precipitation falls below 1000 mm, an exceptional case in the archipelago. The south of New Guinea also shows this distinct dry east monsoon period. The Moluccas however resemble the Pacific type where steady NE to E-trades bring rainfall the whole year round with sharp divisions between luff and leesides. In the Northern winter the monsoon blows in from about the same direction. Rainfall amounts to 2000 : 2500 mm (Braak, 49, I).