Copied from the “Australian Town and Country Journal” Saturday 14 February 1874.
Mr Herbert Ingall contributes an interesting paper to the English Mechanic on the polarisation of haze, which shows how valuable minute observations on meteorological phenomena may become as indications of approaching changes in the weather. He says :— The most important result at which I have arrived, would appear as follows :-That hues of high auroral haze always appear polarised in the direction of a coming disturbance or falling barometer, radiating (as it were) From that spot. The first notice of a coming cyclonic disturbance is often given long before the barometer shows the least sign of falling (frequently while it is still rising from a previous fall), and this is in the appearance (often in a cloudless sky) of faint light gauzy streamers of very high haze, the elevation of which I have little doubt, far exceeds the ordinary clouds, even the cirri, and would appear intermediate between the cirri and the region of the auroral proper, to which I think they are more nearly related. These streamers appear to point out the formation or coining
of a cyclonic or other electric disturbance. The line of polar matter may frequently dissolve and break up without any notable change at the place of observa- tion, as in the case of the disturbance passing off in another direction, and away from the observer. A beautiful instance of this I noticed in London at midnight of October 23rd, 1872, when great bands of haze crossed the sky from W.N.W. to E.S.E., and a sudden decrease of barometrical pressure bringing a heavy S.W.gale, skirted along the N.W. coasts of Scotland, but without causing any marked change at the place of observation. A line instance of persis- tent polarisation of haze and cirri occurred on Septem- ber 11 and 12, 1873 as follows :— September 11, fine morning, light westerly airs, cirri in all shapes, and polar lines of haze streaming from S.W. all day, and exhibiting lunar halo at night. Septem- ber 12, fine morning, light airs, sky almost covered with a gigantic homogeneous broad hand of auroral haze from the S.W. to N.E.. terminating abruptly 10 deg. above the N.W. horizon, where the clear blue sky was seen. The sun exhibited a coloured parhelia in this haze. The barometer had not yet shown any sign of falling even this evening, and only commenced slowly to fall on the 13th, on which morning the true wind of the coming disturbance showed itself com- mencing E.N.E. and veering to S.S.E. This distur- bance proved to be a peculiar large barometrical depression, barring two minima, and crossed England to Denmark, bringing heavy rains and thunder. An interesting feature in these streamers of haze is their occasional luminosity, in which condition they would seem analogous to to true aurora, bnt from which they differ in many respects. They are usually of a very palo-bluish luminosity, not unlike the Milky Way. although scarely so bright, resembling more the palo homogenous glow of the diffused auroral light very frequently seen in the north western horizon, and their transparency is often such as not in the least to interfere with the brilliancy of the stars. These pale streamers are often permanent for a consid- erable time, very different from the sudden and evan- escent brilliancy of the true auroral streamer. They are nevertheless often slowly drifted along by what appears to be high upper currents ofthe atmosphere ; however tho streamers of thc true aurora sometimes drift along in this manner, an instance of which I par- ticularly noted on September 7th, 1871, at 8h., the auroral phenomena consisting simply of pale perpendi- cular streamers from the N.N. W. horizon drifting along from west to east. The following is an instance of luminous streamers almost permanent, as indicating
it coming change, and from this it appears that, the height and permanence of these appearances would in some degree denote the magnitude or intensity of the distant disturbance, as the higher and more filmy the streamers, the more gradual and lasting the change ; but this however, requires further study. January 26, 1873.—-Clear at night. Sky crossed from S. to W. with pale transparent luminous streamers of very light haze, which remained almost stationary. Baro- meter slowly rising. but falling in the South, therefore bringing N. E. winds and cold weather, which contin- ued all the week, and finally culminated in the cyclone of February 2nd, 1873. A curious and I think impor- tant phenomenon to be investigated is the apparent radiation of luminous streamers or lines of haze from distant thunderstorms. My attention was first drawn to this on August 18th, 1870, when after a very hot day (88 deg in shade) an exceedingly violent thunder- storm traversed the western and midland counties of England. The sky was very clear here, but from the distant storm, lines of faintly luminous haze of extreme tenuity appeared to radiate, and retained their position for a very considerable time. Of course thuso phenomena can only be observed with a very clear sky, as the least clouds or mistiness would at once veil from sight the delicate appearances. Again I noticed the same luminous streamer during the storms which traversed the various parts of the country on August 21th of the last year, and on this occasion noted what seems especially important, that their luminosity was more marked in proportion as the various storms from which they radiated intensified. The wild, fantastic forms of cirri often noticed as a forerunner of wind, or either very disturbed weather, would seem to be polarised haze altered by conflicting upper currents, the masses generally radiating, in a flame-like manner, from a given direction, although sometimes the complexity of the forms of cirri, bristling as it were, from each other, would with diffi- culty be explained in this way, the crystalline patterns being only comparable in beauty to the arborescent forms of frozen vapour on a window-pane. I shall not soon forgot the magnificent flaming cirri of June 27th and 28th, 1873 (especially on the latter day), which proceeded the extraordinary weather of June 29th and 30th, 1873.