Volume 14 Australasia - dana ward's homepage

•22 AUSTRALASIA.West of Borneo and the Philippines the meteorological conditions are againmodified by the dijfferences in the outlines and elevations of the great insularmasses. Here mariners no longer speak of trade winds, and recognise themonsoons alone. That of the south-west, sweeping over the Sunda Strait andSumatra, prevails somewhat regularly from the middle of April to the middle ofOctober, in the more open waters stretching awaj' to Formosa.But it is occasionallvinterrupted by the south-eastern winds, and on the insular and continentalseaboards its course is fringed by lateral breezes, eddies, and back-currents, whichenable sailing craft to beat up against the monsoon.This south-west wind which prevails in summer is followed in winter by thenorth-east monsoon, which is in fact the normal polar current. Like the southwestmonsoon it blows throughout half the year, although most intensely inDecember and January. Both seasons are accomjjanied by rains, as well as bysudden gales and storms. But the terrific cyclonic movements of the China Sea,here known as typhoons, that is, Un ftmg, or " great winds," occur chiefly duringthe south-west monsoon in June or July, or else towards the September equinoxwhen the normal annual currents are reversed. These fierce whirlwinds, whichare generally developed in the east, move with spiral action in the direction of thewest or north-west. They are usually more intense in the vicinity of the landthan on the high seas, and fall off rapidly towards the south. Hence thetyphoons rarely extend their range towards the equatorial regions in the watersstretching south of Lucon, largest of the Philippine Islands.Beyond the Sunda Archipelago, that is, in the open sjDace presented by theIndian Ocean as far as the Mascarenhas and Madagascar, the winds are lessinfluenced by insular or continental seaboards, and consequently here acquire a farmore regular course. The zone of the south-east trades, which occupies thesection of the ocean comprised between Australia, Madagascar, and the equator, isuniformly displaced northwards and southwards according to the alternation of theseasons themselves. Thus it is shifted to the north of the equator with themovement of the sun towards the northern hemisphere, while at other times itsrange seldom extends much beyond the 5° of south latitude.But round about the central part of the ocean, dominated by the regularsystem of the south-east trades, there stretches the vast semicircle of lands betweenSouth Africa and Australia, which are fringed by a zone of alternating monsoonssetting landwards during the hot and seawards during the cold season. In noregion of the globe have the monsoons a more regular course than in the northernsection of the Indian Ocean between Somaliland and Sumatra. The south-westmonsoon with its escort of thunderstorms and rains prevails from the middle ofApril to the middle of September throughoiit the Arabian Sea and the Bay ofBengal. It is followed by that of the north-east, that is, the polar current, whichlasts from the middle of October to the middle of March. But in the southernhemisphere the atmospheric system is less regular on the coasts of Australia,Madagascar, and the African mainland; nor is the contrast between land andnater so sharply marked in this region. Here also, as in the China Sea, the clash