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

by T. B. Butler

Again, it is estimated, and on reliable data, that twelve perpendicular feet of water are annually evaporated from the surface of the Red Sea, between Nubia on one side, and Arabia on the other; yet they are both rainless countries, except so far as the inter-tropical belt of rains extends up on to a small portion of them. The moisture of evaporation, floated up from a surface covered by the surface-trade is invariably so combined as to remain uncondensed till it has passed south into the equatorial rainy belt, and over to the opposite hemisphere, and been exposed to the currents of an opposite magnetism.

Again, the N. E. trades extended up in summer over the Mediterranean Sea, an evaporating surface, blow over the Barbary States in June and July, but furnish no rain. And so of the S. E. or N. E. trades which blow over Brazil and other countries in the absence north or south of the tropical belt of rains.

It is obvious from these facts—and more like them might be cited—that mere evaporation, however copious or long continued, does not make the storm or shower in the locality where it takes place, and without the existence and influential agency of a counter-trade; and that reciprocal action, whatever it may be, that takes place between it and the earth.

Again, our own experience is conclusive of this. We have no surface-trade north of 30°, and yet a long drought and great evaporation may follow a wet spring. Belts of droughts and frequent rains occur every year in different portions of the country side by side, and the dividing line follows the course of the counter-trade, and is sometimes distinctly marked for weeks. When a change occurs in the counter-trade, whether from causes existing there or the influence of terrestrial magnetism (in relation to which we shall inquire hereafter), showers form or storms come on: until it does they will not. Efforts at condensation will occasionally appear, but they will be feeble and ineffectual, and occasion a repetition of the axiom that “all signs fail in a drought.” And we may know it from direct observation.

The first indications of a storm, and of most if not all showers, are observable in the counter-trade. These indications, so far as they are visible, are of course to be looked for in the west; although the direction and character of the surface-winds are often indicative of these changes when not visible at the west as we shall see.

The indications are those of condensation, and vary very much in different seasons of the year. It is not my purpose in this place to examine them particularly. They will be alluded to hereafter under the head of prognostics. Suffice it now to say, then, that whether it be the long threads or lines of cirrus which occur in the trade in the winter after a period of severe cold, following the interposition of a large volume of N. W. cold air and the elevation of the counter-trade; or the forms of cirrus which occur at other times and other seasons; or whether it be the ordinary bank at night-fall, or the evening condensation which makes the “circle” around the moon, or the morning cirro-stratus haze which gradually thickens, passes over and obscures the sun, all which may be followed by the easterly scud and winds: they are alike condensation in the trade, the advance or forming condensation of a storm or showers.

The state of the weather, whether hot or cold, is extensively affected by this trade current. As we have already suggested, the mere presence of the sun in its summer solstice, or its absence in winter, is not an adequate cause of all the sudden and various changes to which we are subject. The state of the counter-trade, which is always over, or within influential distance of us, and sometimes probably in contact with us—the nature of the surface-winds which it is at any given time creating and attracting around us, and the electric condition of the surface-atmosphere induced by it, or by the immediate action of the earth’s magnetism, produce those sudden changes which mark our climate. When no intervening surface-winds elevate it above us, and there is no storm or other condensation within influential distance, it induces the gentle balmy S. W. wind of spring—the cooling S. W. wind of summer—the peculiar Indian summer air of autumn, or the comparatively moderate, although cold, open weather of winter. If there be a partial tendency to condensation in it, the cumuli form under the magnetic influence excited by the sunbeams from ten to three o’clock in the day, and float gently away to the eastward, disappearing before night-fall. If the disposition to condensation is stronger, whether inherent or induced by an increased local activity of terrestrial magnetism, these cumuli will increase toward night-fall, or earlier, and terminate me showers; and if it is in a highly electrical state, the still oppressive sultriness which precedes the tornado, and that devastating scourge may appear. If this disposition to condensation becomes extensive, cirri form and run into cirro-stratus, or they extend, coalesce, and form stratus; the surface-wind will be attracted under them, the thermometer fall in summer or rise in winter, and a storm begin. Intense action and sudden cold may exist in and under this counter-trade over the southern portion of the country, while all is calm, warm, and balmy at the north. Heavy snow storms sometimes pass at the south when there are none at the north, and a corresponding state of the weather follows. If a large body of snow fall at the north, the winter is cold, regular, and “old fashioned;” if little snow falls at the north and more at the south, the winter at the north is open and broken. I have known the ice make several inches thick at Baltimore and Washington, when none could be obtained for the ice-houses on the Connecticut shore of Long Island Sound. In short, although heat and cold are mainly dependent upon the altitude of the sun, aided by the other arrangements we have alluded to, yet the counter-trade, and the reciprocal action which takes place between it and the earth, are most powerful agents, mitigating the rigors of winter, bringing about the changes from cold to warm weather which the sun is too far south to produce. And on the other hand, by this reciprocal action, producing the electrical phenomena, the gusts, the tornadoes, the hail storms, and the cool seasons of summer, and the period of intense cold in winter.

All our surface-winds, except the light, peculiar W. S. W. wind which is felt where the counter-trade is in contact with the earth, and which is a part of it, and perhaps the genuine N. W. wind which is very peculiar, are incidents of the trade, and are due to its conditions and attractions. We have already said this was true of the easterly wind and scud of a storm—it is alike true of all. The storm winds east of the Alleghanies are usually, though not always, from the eastward. They are sometimes from the southward, as they doubtless are still more frequently in the interior of the continent.

There is occasionally a southerly afternoon wind, followed by short rains in spring and fall, or a succession of showers in summer, which is rather a precedent wind than a storm wind; blowing toward and under an advance portion of the storm at the north, and hauling to the eastward when the rain sets in, or to the westward when the showers reach us.

When there are no storms, or showers, or inducing electric action in the counter-trade, within influential distance to disturb the surface atmosphere, it is calm. If a storm approaches, or forms within inducing distance, the surface atmosphere is affected and attracted toward the storm, from one or more points, and “blows,” as we say, toward and under it. It commences blowing first nearest the storm, and extends as the storm travels, or becomes more intense and extends its inducing influence. I have repeatedly noticed this in traveling on steamboats and railroads running toward or from, and in several instances through a storm, and telegraphic notices and other investigations prove it. The point from which the surface atmosphere is attracted and blows, depends very much upon the position of the storm in relation to bodies of water and the point of observation, and its shape; and the force with which it may blow will depend much upon its intensity.