Page:Physical Geography of the Sea and its Meteorology.djvu/401

Rh 701. The curved form of the equatorial calm belt in the Indian Ocean.—The equatorial calm belt in the Indian Ocean is a decided curve. The peculiar form may be ascribed to the meteorological influence of the Indian peninsula upon the calm belt, and in this way: The north-east monsoon brings the rainy season to the Coromandel coast and to the east coast of Ceylon. This rainy season embraces the land rather than the sea. The latent heat that is liberated during these rains, together with the effect of the solar ray upon this tongue of land, has the effect of expanding the air over it, and so "deadening" the north-east monsoon. In the mean time, the meteorological influences from Africa on one side, and Australia on the other, tend to draw the wind in towards those lands and so retard the edges of the south-east trades, thus giving the calm belt the curved form shown in the plate.

702. The winter monsoons,—In the winter-time, and during the north-east monsoon, there is in the calm belt which intervenes between that monsoon and the south-east trades, a belt of winter or westerly monsoons. It, too, is curved, as shown (Plate VIII.) by the two lines drawn to represent its mean limits about the 1st of March. This is a most remarkable phenomenon, for which no satisfactory explanation has been suggested. It extends nearly, if not entirely, across the Pacific Ocean also, and the winds all the way in it prevail from the westward. The extreme breadth of this winter monsoon belt is about 9° or 10° of latitude. In the Indian Ocean, its middle is between the equator and 5° S.; in the Pacific, between the equator and 5° N. in the Atlantic, between 5° and 10° N. In the Atlantic it is a summer monsoon easily to be accounted for. This belt of sub-monsoons, considering its great length and small breadth, is one of the most remarkable phenomena in marine meteorology.

703. The monsoons of Australasia.—The north-west monsoons of Australia come from this belt; there it is widened, for these winds extend far down the west coast of that continent. The Malayan and Australasian archipelago have a complication of monsoons and sub-monsoons. The land and sea breezes impart to them peculiar features in many places, especially about the changing of the monsoons, as described by Jansen in his appendix to the Dutch edition of this work: "We have seen," says he "that the calms which precede the sea breeze generally continue longer, and are accompanied with an upward motion of the air,