Outlines of a Mechanical Theory of Storms Part 6

To show that the same calculations are applicable for other times, we will make the calculation for the _centre ascending_, for the 22d December, 1852, taking the following elements:

Moon's mer. pa.s.sage, Dec. 22d 15h. 16m. G. time.

" right ascension, same time 51 57'

" declination north 15 42 " true S. Diameter 886.6?

" distance from node 37 " " " quadrature 52 -------- Which gives the arc AR 29 5 1st correction -1 51 2d +1 11 -------- Corrected arc AQ 28 25 --------

And the lat.i.tude at the time of the meridian pa.s.sage = 42 north, or about forty miles north of Ottawa.

Abstract from the record:--

[14]_Dec._ 21st, 1852. Wind N.-E., fine weather.

_Dec._ 22d. Thick, hazy morning, wind east, much lighter in S.-E. than in N.-W.; 8 A.M., a clear arch in S.-E. getting more to south; noon, very black in W. N.-W.; above, a broken layer of cir. c.u.mulus, the sun visible sometimes through the waves; wind round to S.-E., and fresher; getting thicker all day; 10 P.M., wind south, strong; thunder, lightning, and heavy rain all night, with strong squalls from south.

_Dec._ 23d. Wind S.-W., moderate, drizzly day; 10 P.M., wind west, and getting clearer.

The next day the vortex pa.s.sed the lat.i.tude of Montreal (the moon being on the meridian about 10 P.M.)

MAGNETIC STORM, DECEMBER 23, 1852.

In the July number of Vol. XVI. of Silliman's Journal, we find certain notices of the weather in 1852, by Charles Smallwood, of St. Martins, nine miles east of Montreal. He mentions "two remarkable electrical storms (which) occurred on the 23d and 31st of December, (in which) sparks 5/40 of an inch were constantly pa.s.sing from the conductor to the discharger for several hours each day." At 10 P.M. (23d) the vortex pa.s.sed over Montreal, and again descending on the 31st North, and was visible at Ottowa on the morning of the 1st of January, with southerly wind setting towards it. On the 29th of December, Mr. Smallwood records "a low auroral arch, sky clear." On the 20th, the vortex was 5 to the northward of Montreal, and the aurora was consequently low--the brightest auroras being when the vortex is immediately north without storm, or one day to the northward, although we have seen it _very low_ when the vortex was three days to the north, and no other vortex near.

LIVERPOOL STORM.

On the night of the 24th of December, the same central vortex ascending pa.s.sed between Cape Clear and Liverpool.

On the 25th, at midnight, the vortex pa.s.sed to the north of Liverpool: its northerly progress being very slow, being confined for three days between the parallel of Liverpool and its extreme northern limit in lat.i.tude about 57. The accompanying account of the weather will show the result of a long-continued disturbance near the same lat.i.tude:

The Baltic, three days out from Liverpool, encountered the vortex on the night of the 23d. On the morning of the 25th, very early, the gale commenced at Liverpool, and did much damage. On the 26th, the vortex attained its northern limit; but we have not been able to procure any account of its effects to the northward of Liverpool, although there can be but little doubt that it was violent on the coast of Scotland on the 26th; for the next day (27th) the vortex having made the turn, was near the lat.i.tude of Liverpool, and caused a _tremendous_ storm, thus showing a continued state of activity for several days, or a peculiarly favorable local atmosphere in those parts. It is very probable, also, that there was a conjunction of the central and inner vortex on the 27th. The inner vortex precedes the central in pa.s.sing lat.i.tude 41; but as the mean radius of its...o...b..t is less than that of the central, it attains to a higher lat.i.tude, and has, consequently, to cross the path of the central, in order again to precede it descending in lat.i.tude 41.

As a very trifling change in the elements of the problem will cause great changes in the positions of the vortices on the surface of the earth, it cannot now be a.s.serted that such a conjunction did positively occur at that time; but, it maybe suspected, that a double disturbance would produce a greater commotion, or, in other words, a more violent, storm.

It is on this account, combined with other auxiliary causes, that the vicinity of Cape Horn is so proverbially stormy, as well as for the low standard of the barometer in that lat.i.tude, it is the stationary point of the vortices in ordinary positions of the nodes and perigee of the moon. We have already alluded to the fact, that none of the vortices scarcely ever pa.s.s much beyond lat.i.tude 80, and then only under favorable circ.u.mstances, so that we ought to infer, that gales in high lat.i.tudes should set from the poles towards the storms in lower lat.i.tudes. This is, no doubt, the fact, but, nevertheless, a hard southerly blow _may possibly_ occur in high northern lat.i.tudes, if a storm should be raging very violently in a lower lat.i.tude on the opposite side of the pole, the distance across the circle of 80 being only about 1,400 miles. As the different vortices have a different limit in lat.i.tude every year, the determination of this turning point is obviously of great practical utility, as the fact may yet be connected with other phenomena, so as to give us the probable character of the polar ice at any a.s.signed time. On this point we have more to say.

Pa.s.sAGES OF ALL THE VORTICES.

Our remarks have hitherto been confined to the central vortex. We shall now show from the record, that the other vortices are as effective in deranging the equilibrium of our atmosphere. In the following table we have given the pa.s.sages of the different vortices, which will serve as their true positions within moderate limits, to calculate from, for all future time.

Pa.s.sAGES OF THE CENTRAL AND LATERAL VORTICES, OBSERVED IN JUNE AND JULY, 1853, IN LAt.i.tUDE 41 20' NORTH.

I signifying Inner; O, outer; C, central; A, ascending; D, descending.

____________________________________________________________________ | | | | | | | | Order.|Vortex.| Date. | Meridian |Pa.s.sage.| Calculated lat.i.tude | | | | | Pa.s.sage. | | and Remarks. | |_______|_______|_________|__________|________|______________________| | | | | | | | | 1st | I. A. | June 22 | 7 A.M. | south | Centre. About 40. | | | | 23 | 8 A.M. | north | Warsaw. Storm. | | 2d | O. D. | 27 | 0 noon | north | | | | | 28 | 1 A.M. | south | See record. | | 3d | C. A. | July 1 | 9 A.M. | south | | | | | 2 | 10 A.M. | north | Lat. 43. Storm. | | 4th | I. D. | 7 | 5 P.M. | north | | | | | 8 | 6 P.M. | south | Lat. New York. Storm.| | 5th | C. D. | 12 | 5 P.M. | north | Aurora. | | | | 13 | 6 P.M. | south | Stormy, very. | | 6th | O. A. | 14 | 10 A.M. | south | | | | | 15 | 11 A.M. | north | See Record. | |_______|_______|_________|__________|________|______________________|

The intervals between the ascending and descending pa.s.sages of the different vortices, are

Between I. A. and I. D. from 11 to 14 days.

" O. A. " O. D. " 10 " 12 "

" C. A. " C. D. " 9 " 11 "

and the effect is greatest when the vortex comes to the meridian before the sun, and least when after the sun; in which case the full effect is not developed, sometimes until the following day.

A brief abstract from a journal of the weather for one sidereal period of the moon, in 1853.

_June_ 21st. Fine clear morning (S. fresh)[15]: noon very warm 88; 4 P.M. plumous _cirri in south_; ends clear.

22d. Hazy morning (S. very fresh) arch of cirrus in west; 2 P.M., black in W.-N.-W.; 3 P.M., overcast and rainy; 4 P.M., a heavy gust from south; 4.30 P.M., blowing furiously (S. by W.); 5 P.M., tremendous squall, uprooting trees and scattering chimneys; 6 P.M., more moderate (W.)

23d. Clearing up (N.-W.); 8 A.M., quite clear; 11 A.M., bands of mottled cirri pointing N.-E. and S.-W.; ends cold (W. N.-W.); the cirri seem to rotate from left to right, or with the sun.

24th. Fine clear cool day, begins and ends (N.-W.)

25th. Clear morning (N.-W, light); 2 P.M. (E.) calm; tufts of tangled cirri in north intermixed with radiating streaks, all pa.s.sing eastward; ends clear.

26th. Hazy morning (S.-E) cloudy; noon, a heavy windy looking bank in north (S. fresh), with dense cirrus fringe above on its upper edge; clear in S.

27th. Clear, warm, (W.); bank in north; noon bank covered all the northern sky, and fresh breeze; 10 P.M., a few flashes to the northward.

28th. Uniform dense cirro-stratus, (S. fresh); noon showers all round; 2 P.M., a heavy squall of wind, with thunder and rain (S.-W. to N.-W.); 8 P.M., a line of heavy c.u.muli in south; 8.30 P.M., a very bright and high c.u.mulus in S.-W., protruding through a layer of dark stratus; 8.50 P.M., the cloud bearing E. by S., with three rays of electric light.[16]

[Ill.u.s.tration: Fig. 17]

_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 pa.s.sing off to S; 8 P.M., clear, pleasant.

_July_ 1st. Fine and clear; 8 A.M., cirrus in sheets, curls, wisps, and gauzy wreathes, with patches beneath of darker shade, all nearly motionless; close and warm (N.-E.); a long, low bank of haze in S., with one large c.u.mulus in S.-W., but very distant.

_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 c.u.muli just visible above a gloomy-looking bank of haze in N.-N.-W., (S. very fresh;) warm, 86; more c.u.muli in N.-W.--the whole line of c.u.muli N. are separated from the clouds south by a clear s.p.a.ce. These clouds are borne rapidly past the zenith, but never get into the clear s.p.a.ce--they seem to melt or to be turned off N.-E. The c.u.muli in N. and N.-W., slowly spreading E. and S.; 3 P.M., the bank hidden by small c.u.muli; 4 P.M., very thick in north, magnificent c.u.muli 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.)

_July_ 3d. Very fine and clear, (N.-W.); noon, a line of large c.u.muli in N., and dark lines of stratus below, the c.u.muli moving eastward; 6 P.M., their alt.i.tude 2 40'. Velocity 1 per minute; 9 P.M., much lightning in the bank north.[17]

_July_ 4th. 6 A.M., a line of small c.u.mulo-stratus, extending east and west, with a clear horizon north and south 10 high. This band[18] seems to have been thrown off by the central yesterday, as it moves slowly south, preserving its parallelism, although the clouds composing it move eastward. Fine and cool all day--(N.-W. mod.)--Lightning in N.

_July_ 5th. Cloudy (N. almost calm), thick in E., clear in W.; same all day.

6th. Fine and clear (E. light); small c.u.muli at noon; clear night.

7th. Warm (S. E. light); cirrus bank N. W.; noon (S.) thickening in N.; 6 P.M., hazy but fine; 8 P.M., lightning in N.; 10 P.M., the lightning shows a heavy line of c.u.muli along the northern horizon; calm and very dark and incessant lightning in N.

8th. Last night after midnight commencing raining, slowly and steadily, but leaving a line of lighter sky south; much lightning all night, but little thunder.

8th. 6 A.M. Very low scud (500 feet high) driving south, still calm below, (N. light); 10 A.M., clearing a little; a bank north with cirrus spreading south; same all day; 9 P.M., wind freshening (N. stormy); heavy c.u.muli visible in S.; 10.30 P.M., quite clear, but a dense watery haze obscuring the stars; 12 P.M., again overcast: much lightning in S.

and N.-W.