Page:Physical Geography of the Sea and its Meteorology.djvu/138

112 as to its hypsometry. It is traversed by large icebergs, which are more favourable to the recondensation of its vapours than so many islets would be. Warm waters are in the middle of it, and both the east and the west winds, which waft its vapours to the land, have, before reaching the shores, to cross currents of cool water, as the in-shore current counter to the Gulf Stream on the western side, and the cool drift from the north on the east side. In illustration of this view, and of the influence of the icebergs and cold currents of the Atlantic upon the hypsometry of that ocean, it is only necessary to refer to the North Pacific, where there are no icebergs nor marked contrasts between the temperature of its currents. Ireland and the Aleutian Islands are situated between the same parallels. On the Pacific islands there is an uninterrupted rain-fall during the entire winter. At other seasons of the year sailors describe the weather, in their log-books, there as "raining pretty much all the time." This is far from being the case even on the western coasts of Ireland, where there is a rain-fall of only 47 inches—probably not more than a third of what Oonalaska receives. And simply for this reason: the winds reach Ireland after they have been robbed (partially) of the vapours by the cool temperatures of the ice-bergs and cold currents which lie in their way; whereas, such being absent from the North Pacific, they arrive at the islands there literally reeking with moisture. Oregon in America, and France on the Bay of Biscay, are between the same parallels of latitude; their situation with regard both to wind and sea is the same, for each has an ocean to windward. Yet their annual rain-fall is, for Oregon, 65 inches, for France, 30. None of the islands which curtain the shores of Europe are visited as abundantly by rains as are those in the same latitudes which curtain our north-west coast. The American water-shed receives about twice as much rain as the European. How shall we account for this difference, except upon the supposition that the winds from the Pacific carry (§ 171) more rain than the winds from the Atlantic? Why should they do this, except for the icebergs and cool streaks already alluded to?

284. Limited capacity of winds to take up and transport, for the rivers of Europe and America, vapour from the North Atlantic.—It may well be doubted whether the south-westerly winds—which