The Philosophy of the Weather. And a Guide to Its Changes

by T. B. Butler

Another anomaly which we find in the trade-wind region, is the monsoon. There are several of them, but they are found, in the greatest strength and regularity, in the Indian Ocean. Another, defined by the investigations of Maury, is found on the west coast of Africa, extending out over the Atlantic. Another prevails on the western coast of South and Central America. The etesian winds of the Mediterranean are but the N. E. trades, whose northern limit is carried up in summer, by the transit of the connected machinery, to the north, over that sea. The N. E. and S. E. monsoons, so called, of the Indian Ocean, are but the regular trades, blowing when the belt of rains is absent, as they do all over the globe. The N. W. monsoon, south of the equator, in the vicinity of New Holland; the S. W. monsoon which blows from the Arabian Sea, in upon Hindoostan; the S. W. monsoon of the Atlantic, south of the Cape De Verde Islands; and the variable west monsoon winds of the west coast of Southern and Central America, and Southern Mexico (known under several different names, but chiefly by that of Tapayaguas), are all that deserve attention as such.

At first sight they appear to be anomalies, but the facts declare their character with perfect certainty. First, they are not continuous, like the trades, but prevailing winds, and are storm winds; they always blow toward a region, or portion of the ocean, covered at the time by clouds and falling weather.

Second, they do not blow upon, or toward, heated surfaces of land or water—i. e., toward the dry and parched surfaces, where the dry season prevails, or from adjoining cold waters on to warm surfaces, but toward the land or water situated under the rainy belt. They are therefore incident storm winds, (as our easterly winds are incident storm winds) of the rain clouds of the tropics. They blow in upon the land, under the belt of rains, while that belt with its daily cloud, and inducing electric action, is over it, and follow that belt in its transit north and south. They blow from the warm south polar current of the Atlantic, which flows N. W. from the coast of Africa, toward the inshore north polar current, which is there flowing south, but under the belt of rains. In the Indian Ocean they blow from the center of that ocean, and the Arabian Sea, toward the belt which hangs over Hindoostan, from the S. W.; and when the rainy belt travels south they still blow toward, and under it, from the Indian Ocean, but of course from the N. W. The heated character of the waters of the Indian Ocean and Arabian Sea, which receive no polar currents, but heated waters from the Persian Gulf, and from rivers which flow into the Bay of Bengal over the heated plains of a tropical country, explain this. So, too, the monsoon of the Atlantic Ocean, does not blow north of the Cape De Verde Islands,—where the heated surface of Sahara, burning with the rays of a vertical sun, has a temperature sometimes ranging from one hundred and forty to one hundred and sixty degrees—but remains under the rainy belt, drawn from the heated waters which flow up from the South Atlantic, and travels north as the rainy belt travels north in summer, and south to the Gulf of Guinea, as that travels south in winter. The same is true of the Pacific monsoon, the Tapayaguas, the least marked of all, which blows in during the rainy season upon the west coast of Southern Mexico, and of Southern and Central America. They are all incident rain or storm winds, blowing in upon the land, or on to a colder surface of different polarity, during the rainy season; and if it were possible to catch one of our north-easters, in its passage over our country to the eastward, and anchor it to the Alleghanies, “paying out” so to have it reach in part over the Atlantic, and keep it there in operation six months, we should have a continual easterly wind under it; a monsoon more strongly marked than the monsoons of the Indian, or Atlantic Oceans. The received theory in relation to them is a fallacy.

Recapitulating, then, all the phenomena, we have,—Surface-trades, blowing toward the center, passing through each other, and continuing on as upper or counter-trades; a belt of rains, with calms near the center, formed by the trades where they meet and pass through each other, which travels with them north and south following the sun; two belts of drought, following the belt of rains and the trades, and followed by the extra-tropical line of rains, as it travels with the trades and the rainy belt, leaving a part of the earth which the equatorial rainy belt does not travel far enough north, nor the extra-tropical line of rains far enough south to cover, and which is consequently a rainless region; the monsoons, which are but incidents of the rainy belt, and the gathered volumes of counter-trade, on the west of the two great oceans, which usurp the place of the N. E. trades, carrying the rainy belt up to the region of extra-tropical rain, and preventing the rainless region from encircling the earth.

Upon what cause do these great central phenomena, so vast, so regular, so wonderful, depend? What is the motive power of this connected atmospheric machinery, whose action and influence extend over the entire globe?

“Heat, heat,” say the text books, the Professors, the votaries of meteorology. “All these phenomena are owing to the heat of the sun. It heats the ocean and the earth—the air is thereby heated and rises, the cold air rushes in from below, then the ascended current rolls off each way at the top toward the pole, acquiring a westerly motion from the rotation of the earth, slipping away from under it, and a different, viz.: an easterly motion, after reaching the latitude of 30°, from the same rotation; and all the winds and disturbances of the atmosphere are produced in the same way. They are produced by the action of heated surfaces upon the adjacent atmosphere.”

This is the great theory of meteorologists, by which they attempt to account for the various atmospherical disturbances, of both tropical and extra-tropical regions.

The whole theory is a fallacy—it will not stand the test of a careful examination. The bases of the theory, which are assumed to be facts, are not so. The agent has not the power claimed for it. A heated surface, alone, never caused any considerable ascending current, or if it did, never produced a mile of wind. I repeat it, the theory and all incidental ones—the thousand explanatory and modifying theories, and hypotheses—the whole system—is without foundation in fact, and will not bear a critical examination.

Let us see if this language is stronger than the facts will warrant.

The theory assumes that both the land and water, under this central belt, where the air is supposed to be rising are materially hotter than the land and ocean are on either side of it. Now, how much hotter are the air and the land under the belt of rains and calms, upon Hindoostan, or Africa, or South America, where the former is supposed to be acquiring heat and expansion so rapidly, and to be ascending, than under, and in the dry belts on either side? None; it is cooler by the thermometer—much cooler.