It is to be noted that the climate of the islands of the Pacific becomes more and more healthy the farther they are from the monsoon region.
There are two seasons of rainfall over the province: the monsoon season, when supplies of moisture are brought up by the ocean winds from the Arabian Sea and the Bay of Bengal; and the winter season, when storms advancing eastwards from Persia and the Caspian districts occasion winds, widespread rain and snowfall.
Tibet is affected by the south-west monsoon, just as the Pamirs are affected, but in varying degrees according to geographical position.
The wet season, lasting during the prevalence of the south-west monsoon, from April to December, is clearly defined on the Pacific slope.
The south-west monsoon does not generally extend, in its character of a south-west wind, over the land.
In the two years 1899 and 1900 the monsoon was very weak, the result being a severe famine which caused great mortality among the Bhil population.
This appears to be about the northern limit reached by the south-west monsoon, which from June to September brings a fairly abundant rainfall to the Yemen highlands, though the Tehama remains almost entirely rainless.
The northwest monsoon, beginning in October and lasting till March, brings the principal rainy season in the archipelago.
Within the southern monsoon region there is a gradual transition to the northwest monsoon of New Guinea in low latitudes, and in higher latitudes to the north-east wind of the Queensland coast.
At this period an exact knowledge of the depths of the ocean off after the beginning of the south-west monsoon to a minimum assumed an unlooked-for practical importance from the daring in August, the total range being 92 in.
The characteristic feature of the south-western Pacific is therefore the relatively low pressure and the existence of a true monsoon region in the middle of the tradewind belt.
The southwest monsoon which brings rain in Cochin-China coincides with the dry season in Annam, the reason probably being that the mountains and lofty plateaus separating the two countries retain the precipitation.
The wet season - May to October - corresponds with the prevalence of the south-west monsoon in the Bay of Bengal.
The surface currents of the Pacific have not been studied in the same detail as those of the Atlantic, and their seasonal variations Circulation are little known except in the monsoon regions.
Owing to its tropical situation and its almost entire dependence upon the monsoon rains, India is more liable than any other country in the world to crop failures, which upon occasion deepen into famine.
Per annum, and that of the east coast, where the north-east monsoon breaks with all its fury, is usually about 1 55 in.
The diurnal mountain winds are very strongly marked on the Himalaya, where they probably are the most active agents in determining the precipitation of rain along the chain - the monsoon currents, as before stated, not penetrating among the mountains.
The rainfall of the province is considerably heavier than in northern India, and the result of this is a cooler and more pleasant atmosphere during the monsoon season.
The influence of the monsoon is greatly moderated before it reaches this region, and the rains sometimes fail altogether.
In Annam the rainy season begins during September and lasts for three or four months, corresponding with the northeast monsoon and also with a period of typhoons.
On the Swahili coast the south-east monsoon begins in April and the northeast monsoon in November.
A great part of the land-forces had been already sent off under Craterus in the earlier summer to return west by Kandahar and Seistan; the fleet was to sail under the Greek Nearchus from the Indus mouth with the winter monsoon; Alexander himself with the rest of the land-forces set out in October to go by the 2 Beside V.
Thus the south-west monsoon begins in the Arabian Sea with west and north-westerly winds,which draw round as the year advances to south-west and fall back again in the autumn by northwest to north.
In the Bay of Bengal the strength of the southwest monsoon is rather from the south and south-east, being succeeded by north-east winds after October, which give place to northerly and north-westerly winds as the year advances.
Dobbo, on a small western island, is the chief place; its resident population is reinforced annually, at the time of the west monsoon, by traders from that quarter, who deal in the tripang, pearl shell, tortoise-shell, and other produce of the islands.
The cool season begins with the commencement of the north-east monsoon in the China Sea in November.
The Equatorial CounterCurrent flowing eastwards is largely assisted during the latter half of the year by the south-west monsoon, and from July to October the south-west winds prevailing east of 150° E.
As to cost, one transatlantic cable repair cost 75,000; the repair of the Aden-Bombay cable, broken in a depth of 1900 fathoms, was effected with the expenditure of 176 miles of new cable, and after a lapse of 251 days, 103 being spent in actual work, which for the remainder of the time was interrupted by the monsoon; a repair of the Lisbon-Porthcurnow cable, broken in the Bay of Biscay in 2700 fathoms, eleven years after the cable was laid, took 215 days, with an expenditure of 300 miles of cable.
During the north-east monsoon, from the middle of October to the middle of April, dry weather prevails and the thermometer averages from 77° to 80° F.
During the south-west (summer) monsoon great quantities (67 in.) of rain fall, especially in July and August.
And in May at the end of the north-east monsoon, and a rapid falling io S.
On the east coast the force of the north-east monsoon, which beats upon the shores of the China Sea annually from November to February, has kept the land for the most part free from mangroves, and the sands, broken here and there by rocky headlands thickly wooded, and fringed by casuarina trees, stretch for miles without interruption.
The south-westerly winds which prevail north of the equator during the hot half of the year, to which navigators have given the name of the south-west monsoon (the latter word being a corruption of the Indian name for season), arise from the great diminution of atmospheric pressure over Asia, which begins to be strongly marked with the great rise of temperature in April and May, and the simultaneous relatively higher pressure over the equator and the regions south of it.
This diminution of pressure, which continues as the heat increases till it reaches its maximum in July soon after the solstice, is followed by the corresponding development of the south-west monsoon; and as the barometric pressure is gradually restored, and becomes equalized within the tropics soon after the equinox in October, with the general fall of temperature north of the equator, the south-west winds fall off, and are succeeded by a north-east monsoon, which is developed during the winter months by the relatively greater atmospheric pressure which then occurs over Asia, as compared with the equatorial region.
To be the fall at Peking; while at Canton, which lies nearly on the northern tropic and the region of the south-west monsoon is entered, the quantity is increased to 78 in.
During the southwest monsoon, from the middle of April to the middle of October, rain falls daily and the temperature varies between 85° and 95°.
Its mountains are insufficient in elevation and extent to attract their full share of the monsoon rains, which fall so abundantly on the Abyssinian highlands on the other side of the Red Sea; for this reason Arabia has neither lakes nor forests to control the water-supply and prevent its too rapid dissipation, and the rivers are mere torrent beds sweeping down occasionally in heavy floods, but otherwise dry.
Of Aden, the summer heat is tempered by the monsoon winds, and the seasonal variation of temperature is less marked.
On the northern shore of Hong-Kong there is a patent slip at East or Matheson Point, which is serviceable during the north-east monsoon, when sailing vessels frequently approach Victoria through the Ly-ee-mun Pass.
Sea-snakes occasionally make their way to Japan, being cairied thither by the Black Current (Kuro Shiwo) and the monsoon, but they must be regarded as merely fortuitous visitors.
In winter, for example, when the northern monsoon begins to blow, numbers of denizens of the Sea of Okhotsk swim southward to the more genial waters of north Japan; and in summer the Indian Ocean and the Malayan archipelago send to her southern coasts a crowd of emigrants which turn homeward again at the approach of winter.
These, like the mollusca, indicate the influence of the Kuro Shiwo and the south-west monsoon, for they have close affinity with species found in the Indian and Pacific Oceans.
During the monsoon the climate is very damp, and at times even cold and raw, thick clouds and mist enveloping the sky for many days together.
Rain comes with the south-east monsoon, and on the northern part of the coast the rainy season is divided into two parts, the great and the little Masika: the former falls in the months of September, October, November; the latter in February and March.
The slopes of the plateau which face the rain-bringing monsoon are in some places covered with primeval forest, in which timber is plentiful.
Abandoned since 495 - for Kasyapa was eventually slain during a battle fought in the plain beneath - it has, on the whole, well withstood the fury of tropical storms, and is now used again to gain access to the top. When rediscovered by Major Forbes in 1835 the portions of the gallery where it had been exposed for so many centuries to the south-west monsoon, had been carried away.
The most striking general fact as regards climate in the archipelago is that wherever that part of the south-east monsoon which has passed over Australia strikes, the climate is comparatively dry, and the vegetation is less luxuriant.
Except in the east of the Pacific, the south-east trade is only fully developed during the southern winter; at other seasons the regular trade-belt is cut across from north-west to south-east by a band twenty to thirty degrees wide, in which the trades alternate with winds from north-east and north, and with calms, the calms prevailing chiefly at the boundary of the monsoon region (5° N.-15° S., 160°-185° E.).
On reaching the western Pacific part of this current passes southwards, east of New Zealand, and again east of Australia, as the East Australian Current, part northwards to join the Equatorial CounterCurrent, and during the north-east monsoon part makes its way through the China Sea towards the Indian Ocean.
During the south-west monsoon this last branch is reversed, and the surface waters of the China Sea probably unite with the Kuro Siwo.
The north-west coast, particularly the portions north of Cambridge Gulf and the shores of the Gulf of Carpentaria, are favoured with an annual visitation of the monsoon from December to March, penetrating as far as Soo m.
The full force of the monsoon is, however, broken by the western frontier hills; and while the rainfall at Mergui is over 180, and at Moulmein 240 in., that of Bangkok seldom exceeds 54, and Chiengmai records an average of about 42 in.
The people depend so entirely upon agriculture, and the harvest is so entirely destroyed by a single monsoon failure, that wherever a total failure occurs the landless labourer is immediately thrown out of work and remains out of work for the whole year.
Along the parallel of 33° N., and arrests the monsoon currents), is subject to much the same climatic influences as the eastern Himalaya.
The flora of Siberia presents very great local varieties, not only on account of the diversity of physical characteristics, but also in consequence of the intrusion of new species from the neighbouring regions, as widely different as the arctic littoral, the arid steppes of Central Asia, and the wet monsoon regions of the Pacific littoral.
In the monsoon regions the half-yearly change from on-shore to off-shore winds produces noticeable differences in XIX.
The heated body of air carried from the Indian Ocean over southern Asia by the south-west monsoon comes up highly charged with watery vapour, and hence in a condition to release a large body of water as rain upon the land, whenever it is brought into circumstances which reduce its temperature in a notable degree.
Throughout the whole of the moister parts of the province the agricultural season is the wet period of the south-west monsoon, lasting from the middle of May until November.
The cessation of the rains on the southern border of Baluchistan, west of Karachi, obviously arises from the projection of the south-east coast of Arabia, which limits the breadth of the south-west monsoon air current and the length of the coast-line directly exposed to it.
Four seasons are recognized - January - April, very dry and great heat; May - June, cooler and the " heavy " rains; July - September, the season of extreme heat and the south-west monsoon; October - December, the " light " rains.
In the South Pacific the northwest monsoon of Australia affects a belt running east of New Guinea to the Solomon Islands.
The warmed air of summer produces an area of low pressure in the west-central United States, which interrupts the belt of high pressure that planetary conditions alone would form around the earth about latitude 30; hence there is a tendency of the summer winds to blow inward from the northern Pacific over the Cordilleras toward the continental centre, and from the trades of the torrid Atlantic up the Mississippi Valley; conversely in winter time, the cold air over the lands produces a large area of high pressure from which the winds tend to flow outward; thus repelling the westerly winds of the northern Pacific and greatly intensifying the outflow southward to the Gulf of Mexico and eastward to the Atlantic. As a result of these seasonal alternations of temperature and pressure there is something of a monsoon tendency developed in the winds of the Mississippi Valley, southerly infiowing winds prevailing in summer and northerly outfiowing winds in winter; but the general tendency to inflow and outflow is greatly modified by the relief of the lands, to which we next turn.