Outlines of a mechanical theory of storms

June 29th. A stationary stratus over all, (S.-W. light); clear at night, but distant lightning in S.

30th. Stratus clouds (N.-E. almost calm); 8 A. M., raining gently; 3 P. M., stratus passing off to S; 8 P. M., clear, pleasant.

July 2d. At 5 A. M., overcast generally with hazy clouds and fog of prismatic shades, chiefly greenish-yellow; 7 A. M., (S.-S.-E. freshening,) thick in W; 8 A. M., (S. fresh) much cirrus, thick and gloomy; 9 A. M., a clap of thunder, and clouds hurrying to N.; a reddish haze all around; at noon the margin of a line of yellowish-red cumuli just visible above a gloomy-looking bank of haze in N.-N.-W., (S. very fresh;) warm, 86°; more cumuli in N.-W.—the whole line of cumuli N. are separated from the clouds south by a clear space. These clouds are borne rapidly past the zenith, but never get into the clear space—they seem to melt or to be turned off N.-E. The cumuli in N. and N.-W., slowly spreading E. and S.; 3 P. M., the bank hidden by small cumuli; 4 P. M., very thick in north, magnificent cumuli visible sometimes through the breaks, and beyond them a dark, watery back-ground, (S. strong); 4.30 P. M., wind round to N.-W. in a severe squall; 5 P. M., heavy rain, with thunder, &c.—all this time there is a bright sky in the south visible through the rain 15° high; 7 P. M., clearing, (S.-W. mod.)

“A great number of boxes, bales, and packages of goods lay upon the main floor, among which the water poured down from the edge of the gallery floor in destructive quantities; Fortunately but few goods were opened, and were upon the tables, or the damage would have been irreparable. As it is, we fear some of the goods are injured. In the height of the storm, the centre portion of the fanlight over the western entrance burst in, and several single lights were broken, by staging or otherwise.

“In Williamsburgh, the storm lasted about fifteen minutes, doing an incalculable amount of damage to dwellings, foliage, &c. Hailstones came down in sizes from that of a hickory-nut to a large apple, some with such force as to drive them through the cloth awnings.

“The storm passed over Brooklyn lightly, in comparison with the effects across the Williamsburgh line. On Flushing avenue, beyond the Naval Hospital, a number of trees were uprooted, and the window-panes of the houses shattered. On the corner of Fulton and Portland avenues, three buildings were unroofed, and the walls of the houses were sprung to the foundation.

“On Spencer street, a new frame building was levelled with the ground. Along Myrtle, Classon, and other streets and avenues of East Brooklyn, many of the shade trees were uprooted, and the windows smashed. In Jay street, two trees were struck by lightning, but no other damage ensued.

“Several schooners at the foot of Jay street were forced from their moorings, but were soon after secured. A small frame house in Spencer street, just put under roof, was prostrated to the ground.

11th. Fine clear morning (N.-E.); same all day; no lightning visible to-night, but a bank of clouds low down in south, 2° high, and streaks of dark stratus below the upper margin.

12th. Fine and clear (N.-E.); noon, a well defined arch in S.-W., rising slowly; the bank yellowish, with prismatic shades of greenish yellow on its borders. This is the O. A. At 6 P. M., the bank spreading to the northward. At 9 P. M., thick bank of haze in north, with bright auroral margin; one heavy pyramid of light passed through Cassiopæa, travelling westward 1½° per minute. This moves to the other side of the pole, but not more inclined towards it than is due to prospective, if the shaft is very long; 11.10 P. M., saw a mass of light more diffuse due east, reaching to Markab, then on the prime vertical. It appears evident this is seen in profile, as it inclines downwards at an angle of 10° or 12° from the perpendicular. It does not seem very distant. 12 P. M., the aurora still bright, but the brightest part is now west of the pole, before it was east.

13th, 6 A. M. Clear, east and north; bank of cirrus in N.-W., i.e., from N.-N.-E. to W. by S.; irregular branches of cirrus clouds, reaching almost to south-eastern horizon; wind changed (S.-E. fresh); 8 A. M., the sky a perfect picture; heavy regular shafts of dense cirrus radiating all around, and diverging from a thick nucleus in north-west, the spaces between being of clear blue sky. The shafts are rotating from north to south, the nucleus advancing eastward.

Appearance of the central vortex descending at 8 A. M., July 13th, 1853:

15th. Last night a black squall from N.-W. passed south without rain; at 3 A. M. clear above, but very black in south (calm below all the time); 9 A. M., the bank in south again throwing off rays of cirri in a well-defined arch, whose vortex is south: these pass east, but continue to form and preserve their linear direction to the north; no lightning in south to-night.

16th. Clear all day, without a stain, and calm.

17th. Fine and clear (N.-E. light); 6 P. M., calm.

18th. Fair and cloudy (N.-E. light); 6 P. M., calm.

19th. Fine and clear (N. fresh); I. V. visible in S.-W.

Having begun and ended this record of the weather with the passage of the Inner vortex ascending, it may not be amiss to notice one more, (the August passage,) as it offers a peculiarity not often so distinctly marked. We have alluded to the greater force of the storms when the passage of the vortex corresponds to the passage of the line of low barometer or the depression point of a great atmospheric wave, which is also due to the action of the ether. In consequence of these waves passing from west to east, the storm will only be violent when formed a little to the westward. If the storm forms to the eastward, we neither see it nor feel it, as it requires time to develop its strength, and always in this latitude travels eastward; so that storms may generally be said to come from the west, although the exciting cause travels from east to west. In the case now alluded to, the weather indicated a high barometer, and the storm formed immediately to the eastward, even showing a distinct circular outline. We subjoin a description.

August 15th. Clear morning (N.-E.), a bank of cumuli in south: noon quite cloudy in S. and clear in north. (N.-E.)

17th. Fine clear morning (W.); noon, scattered cumuli in north; 6 P. M., a beautifully regular arch of dense cumuli and cirrus margin in N.-E., with a constant glimmer of lightning; 7 P. M., very clear to the west, and north-west, and south; along the northern horizon a line of high peaked cumuli terminating in N.-N.-W.; a continued roll of distant thunder in the circular bank in N.-E., and not a moment’s cessation to the lightning; the electric excitement advancing westward along the lines of cumuli; the cirrus haze also rising and passing towards S.-W.; 8 P. M., the sky alive with lightning, the cirrus now reaches the zenith; no streaks of lightning coming to the earth; they seem to radiate from the heaviest mass of cumuli, and spread slowly (sufficiently so to follow them) in innumerable fibres over the cloudy cirrus portion of the sky; every flash seems to originate in the same cloud; 8.30 P. M., one branching flash covered the whole north-eastern half of the sky, no leafless tree of the forest could show so many branches; 9.30 P. M., all passed to S.-W. without rain, leaving behind a large cumulus, as if it lagged behind. From this cumulus a straight line of lightning shot up 10° above the cloud into a perfectly clear sky, and terminated abruptly without branching.

We have been thus particular in giving these details, as this was a clear case confirming the principles advanced, that the vortices do not form a continuous line of disturbance, in their daily passage around the earth. It shows also that the barometer, in connection with these principles, will be a far more useful instrument than it has yet proved itself, for practical service as an indicator of the weather.

OBJECTIONS TO LUNAR INFLUENCE.

It may, however, be urged, that if the sidereal period of the moon be approximately a cycle of change, it would have been detected long ago. One reason why this has been so long concealed, is the high latitude of the observers. Spain, Italy, and Turkey, are better situated than other European countries; but the scientific nations lie further north; and from these the law has gone forth to regulate more southern lands. In the United States, particularly in the great plains of the west, the weather can be better compared; not only on account of the latitude being more favorable, but also on account of the greater magnetic intensity of the western hemisphere.

But it may be again asked, why should not the weather be the same generally, in the same latitude, if this theory be true? If the earth were a globe of level land, or altogether of water, no doubt it would be similar; but it must be remembered, that both land and water are very unequally distributed: that the land is of varying extent and elevation—here a vast plain, far removed from the ocean, and there a mountain chain, interposing a barrier to the free course of the atmospheric currents; sometimes penetrating in full width into the frigid zone, and again dwindling to a few miles under the equator. One very important distinction is also to be remarked, in the superficial area of the different zones, reckoning from the equator, and taking the hemisphere as 100 parts:

The summer of many countries is always dry—California for instance. In winter, in the same country, the rains are apparently incessant. This of course depends on the power of the sun, in diverting the great annual currents of the atmosphere. As long as the dry north-west trade sets down the coast of California, the circumstances are not favorable for giving full development to the action of the vortices. When the trade wind ceases, and the prevailing winds come from the south, loaded with vapor, the vortices produce storms of any magnitude; but (and we speak from two years’ observation) the passages of the vortices are as distinctly marked there in winter time, as they are in the eastern States; and in summer time, also, they are very perceptible. The same remark applies to Mediterranean countries, particularly to Syria and Asia Minor; although the author’s opportunity for observing lasted only from April to December, during one season. If we are told it never rains on the coast of Peru, or in Upper Egypt, it does not seriously militate against the theory. The cause is local, and the Samiel and the sand storm of the desert, is but another phase of the question, explicable on the same general principles. From the preceding remarks it will be seen, that in order to foretell the character of particular days, a previous knowledge of the weather at that particular place, and for some considerable time, is requisite; and hence the difficulty of laying down general rules, until the theory is more fully understood.

We now come to the causes which are auxiliary and interfering. It is natural that we should regard the sun as the first and most influential of these causes, as being the source of that variation in the temperature of the globe, which alternately clothes the colder regions in snow and verdure. The heat of the sun undoubtedly causes the ether of the lower atmosphere to ascend, not by diminution of its specific gravity; for it has no ponderosity; but precisely by increase of tension, due to increase of motion. This aids the ascensional movement of the air, and therefore, when a vortex is in conjunction with the sun, its action is increased—the greatest effect being produced when the vortex comes to the meridian a little before the sun. This has a tendency to make the period of action to appear dependent on the phases of the moon, which being the most palpable of all the moon’s variations, has been naturally regarded by mankind as the true cause of the changes of the weather. Thus Virgil in his Georgics, speaking of the moon’s influence and its signs:

“Sin ortu in quarto (Namque is certissimus auctor)
Pura, nec obtusis per cœlum cornibus ibit;
Totus et ille dies, et qui nascentur ab illo,
Exactum ad mensem, pluviâ ventisque carebunt.”

Hence, also, in the present day we hear sailors speak of the full and change, or the quartering of the moon, in connection with a gale at sea; thus showing, at least, their faith in the influence of the phenomenon. Yet it is actually the case, at certain times, that in about latitude 40° and 41°, the storms appear about a week apart.

Another period which must influence the character of different years, depends on the conjunction of the perigee of the lunar orbit with the node. Taking the mean direct motion of the moon’s perigee, and the mean retrograde motion of the node, we find that it takes six years and one day nearly from conjunction to conjunction. Now, from the principles laid down, it follows, that when the perigee of the orbit is due north, and the ascending node in Aries, that the vortices of the earth will attain their greatest north latitude; and when these conditions are reversed, the vortices will reach their highest limit in the lowest latitude. This will materially affect the temperature of the polar regions. In the following table, we have calculated the times of the conjunctions of the apogee and pole of the orbit, taking the mean motions. It may be convenient to refer to by-and-bye, remembering that when the conjunction takes place due south, the vortices reach the highest, but when due north, the vortices in the northern hemisphere have their lowest upper limit:

By this we see that the vortices have never attained their highest limit during the present century, but that in 1858 their range will be in a tolerable high latitude, and still higher in 1876—neglecting the eccentricity of the orbit.

A very potent influence is also due to the heliocentric longitude of the sun, in determining the character of any given year. Let us explain: