Page:Physical Geography of the Sea and its Meteorology.djvu/153

Rh of rain. They should be on the slopes of those mountains which the trade-winds or monsoons first strike after having "blown across an extensive tract of ocean. The more abrupt the elevation, and the shorter the distance between the mountain top and the ocean (§ 298), the greater the amount of precipitation. If, therefore, we commence at the parallel of about 30° north in the Pacific, where the north-east trade-winds first strike that ocean, and trace them through their circuits till they first meet high land, we ought to find such a place of heavy rains. Commencing at this parallel of 30°, therefore, in the North Pacific, and tracing thence the course of the north-east trade-winds, we shall find that they blow thence, and reach the region of equatorial calms near the Caroline Islands. Here they rise up; but, instead of pursuing the same course in the upper stratum of winds through the southern hemisphere, they, in consequence of the rotation of the earth (§ 207), are made to take a south-east course. They keep in this upper stratum until they reach the calms of Capricorn, between the parallels of 30° and 40°, after which they become the prevailing north-west winds of the southern hemisphere, which correspond to the south-west of the northern. Continuing on to the south-east, they are now the surface winds; they are going from warmer to cooler latitudes; they become as the wet sponge (§ 292), and are abruptly intercepted by the Andes of Patagonia, whose cold summit compresses them, and with its low dew-point squeezes the water out of them. Captain King found the astonishing fall of water here of nearly thirteen feet (one hundred and fifty-one inches) in forty-one days; and Mr. Darwin reports that the surface water of the sea along this part of the South American coast is sometimes quite fresh, from the vast quantity of rain that falls. A similar rain-fall occurs on the sides of Cherraponjie, a mountain in India. Colonel Sykes reports a fall there during the south-west monsoons of 605¼ inches. This is at the rate of 86 feet during the year; but King's Patagonia rain-fall is at the rate of 114 feet during the same period. Cherraponjie is not so near the coast as the Patagonia range, and the monsoons lose moisture before they reach it. We ought to expect a corresponding rainy region to be found to the north of Oregon; but there the mountains are not so high, the obstruction to the south-west winds is not so abrupt, the highlands are farther from the coast, and the air which these winds carry in their