Industrial and commercial South America

by Annie S. Peck

Climate

As three quarters of South America lie within the tropics, the entire north coast, and the wider part of the continent including most of Brazil with the countries on the west as far down as the northern part of Chile, a tropical climate and productions might here be expected. But happily within the torrid zone of both hemispheres are the loftiest mountain ranges of the world. These modify the climate of large sections to such a degree that in many places there is perpetual spring, a perennial May or June; in other districts one may in comparatively few hours go from regions of eternal summer to perpetual snow, finding on the way the products of every clime. Thus the mountains and table-lands of South America are effective in causing moderate temperatures over extensive areas within the tropics, with accordant productions.

In comparing the climates of North and South America we must note that while the tropical region of the latter is much the larger, in corresponding latitudes it is in general cooler south of the equator than north. An examination of the isothermal lines, that is the lines of equal average heat around the globe, shows:

First, that the line of greatest heat, a mean temperature of 85°, is north of the equator most of the way. In the Western Hemisphere it runs well up into Central America; then it passes along the northeast coast of South America to a point just below the equator and the mouth of the Amazon, going far north again in Africa.

Second, that of the mean annual isotherms of 65°, which are regarded as the limits of the hot belt, the one in the Northern Hemisphere runs 30° or more from the equator, while that in South America hardly touches the 30th parallel, and on the west coast approaches the equator to within 12°: which means that the tropical region extends much farther north of the equator than it does south.

Third, that of the isotherms of 50° for the warmest month, which are considered as the polar limits of the temperate zones, the one is much nearer to the north pole than the other is to the south. Great masses of water, we know, have a tendency to equalize climate, as the water heats and cools more slowly than the land; but they do not make the average temperature higher. From the movement of the waters of the ocean their temperature over the globe is more nearly equal, while the stable land of broad continental masses has temperatures more nearly corresponding to the latitude, though with greater daily and annual extremes. But for practical purposes, that is for its effect on vegetation, the amount of heat received in summer is of more consequence than the extreme cold of winter. For this reason the temperature of the warmest month instead of the annual mean is taken as the measure; for if that month’s mean temperature is below 50°, cereals and trees will not grow. The broad land masses in the Northern Hemisphere have a greater summer heat than the narrow stretch of land in extreme South America. The greater cold of winter in the north temperate zone does no harm.

We may observe further that in the Northern Hemisphere the west coasts of both continents are warmer in the same latitude than the east, at least in the temperate zone, while in South America a good part of the west coast within the tropics is much cooler than the east. In the temperate zone the variation is slight.

In the matter of rainfall, a most important factor of climate and production, South America is favored with a liberal supply, the arid portions being comparatively small in area, and many of these easily capable of irrigation and of resulting excellent crops.

Dividing the continent into tropical and temperate regions, the former includes (lowlands only) the entire north coast, the whole of Colombia with ports on the Pacific, and Ecuador beyond, the low interiors of Peru and Bolivia, and around on the east the greater part of Brazil, far beyond the mouth of the Amazon; these sections have much in common as to climate and productions. Below Ecuador on the west coast, though still in the torrid zone, we find cooler weather, practically no rain, and for 1600 miles a desert region; beyond this there is a temperate climate with gradually increasing rainfall, and at last in southern Chile too much. On the east coast tropical weather and products continue till we pass Santos and the Tropic of Capricorn, followed by sub-tropical and temperate climates and production. The mountainous regions even at the equator have cooler weather, the temperature ever lowering with increase of altitude.