The Circumhorizontal Arc
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486 MONTHLY WEATRER REVIEW. OCTOBEB,1902 mher, L. r6 Reifheizen" in Kllrnten. P. 435. Local observers ascribe this steady decline to a coincident Stentzel, A. Selbstleuohtende Nachtwolken. P. C45. decrease in the force of the southwest monsoon. -Halo zu Archen vom 3 April 1902. I?. 427. -Angot iiber Hllufigkeit des Regens in Paris. P. 428. The theory, based on these facts, is that the failure in the Polie, P. Ergebnisse der Wind-und Gewitter-Beobachtungen zu inonsoon is due to alterations in the Japan Current, and that Aachen 1873-1900. Pp. 429-430. these alterations in turn are caused by deep sea seismic dis- MacDowall, Alex. B. Teniperatur und Regen. P. 430. turbances, which have culminated in the numerous volcanic Halm, J. Eine neue Sonnentheorie. 430-435. Rotch, A. L. Windmessungen zur See. Pp. 435-436. eruptions which have recently taken place in various parts of -Ueber die Ursache der jiihrlichen Periode der Polarlichter. Yp. the world. 436-437. Whatever the cause, it is certain that the continued and Ward, R. DeC. Irisirende Wolken. Pp. 437-438. increasing shortage of rainfall is lessening the productive Palie, P. Beitrilge zur Kenntniss der Wolkengeschwindigkeit. I. Tggliche Perlode der Wolkengeschwindigkeit. Pp. 441453. power of this portion of China, and is causing much hardship Koes, K. Iiimmtiefen-Beobachtungen. Pp. 453-459. and discontent. Brennecke, W. Ueber die Messung der Lufttemperatur auf den1 [NoTE.-hch periods of small and large annual rainfall Brocken. Py. 459-463. occur all over the world in succession and have to do with the -Heinrich Wild. P. 463. Hellmann, G. Wolkenbruch in Berlin am 14 April 1903. Pp. 46% general circulation of the atmosphere; earthquakes, ocean CUF- 465. rents, etc., do not explain them. Changes in the amount and Laeka, W. Ueber die charakteristischen Zahlen der meteorolo- quality of the heat received from the sun, or of the heat radi- giscnen Elemente. Pp. 465-468. ated from the earth and the atmosphere, would affect the Melander, G. Ueber die Absorption der AtmosphLre. Pp. 468- 470. temperature ancl circulation of the atmosphere, and, therefore, -Regenfall auf den Salomo-Inseln. Pp. 470-471. the local rainfalls. An equally important factor is the internal -Kllma von Oxford. P. 471. mechanism of the atmosphere and the moclifications of the gen- Danckelman, v. Resultate der meteoivlogischen Beobauhtungen eral circulation that can occur within t~ limited range under a in Swakopmund irn Jahre 1901. Pp. 471-473. Satke, L. Hiliiflgkeit und Stiirke der Winde in Iirakaii. Pp. 473- constant rate of radiation from the sun. These two sources of 474. change in meteorological phenomena must be thoroughly in- Hellmann, 0. Intensitiit der Platzregen in Batavia. Pp. 474-4776. vestigated and evaluated before undertaking the study of such -Die Barographenkurve wiihrend des Teifuns vom 2 to 3 August, minor matters as the iufiuence of earthquakes and ocean cur- 1901. P. 475. Roeenthal, R. Schneefall am 18 Juli 19V2 zu Irkutsk. Pp. 475- rents.-C. -4.1 476. Pockel, A. Beobachtungen des elektrisahen ZerstreuungsverniG- THE CIRUUMHORIZONTAL ARC. gens der Atmosphlre und des Putentialgefalles im sudlichen AIgier By Loom BRRSCN,Paris, Frauce, dated November 12, 1902. und an der Kuste von Tunis. Pp. 476-479. Szalay, L. v. Ueber die Eigenthumlichkeit einzelner Blitze. Pp. In the MONTHLYWEATHER REVIEW for June, 1902, Vol. XSS, 479-480. p. 317, there is reproduced a very interesting observation by -Einige mittlere meteorologische Elernente fur die Seychellen Dfr. J. A. Warren, of Santee, Nebr., who, on the 23d of June last, und Rodrigues. P. 480. -Resulbte der meteorologischen Beobachtungen in der Unige- saw a rainbow arc parallel to the .horizon at about 45' below bung der Kapstadt in verrjchiedenen Seehiihen. Pp. 480482. the sun. In commenting upon this observation the Editor -Bakteriengehalt der Luft auf dem Mont Blanc. Pp. 482-4H3. says that, so far as he knows, this is the first description of a -Ben Nevis. P. 483. horizontal circle tangent to the halo of 46' at its lowest point. Weeendonk, K. v. Zur ErklBrung des Phtinomens der blauen Some. Pp. 483-485. This particular tangential arc has a name in optical mete- -Ueber wolkenbruchartige Regenfalle in Aachen. P. 485. orology; it is called the circumhorizontal arc. In his '< Note on -Meteorologische Beobachtungen im alten Kijnigreich Kongo. halos," published in the Annuaire Mhtiorologique de France Pp. 485-486. for 1851, Bravais Bays that the theory of this arc is due to -Ergebnisse der Regenmessungen an der Station Kete-Eratyi (Togoland) in den Jahren 1898-1901. Pp. 486-487. Qalle; it is caused by the refraction of the light in the diedral Wolfer, A. Provisorische Sonnenflecken-Relativzahlenf iir des 111. angles of 90' at the lower base of the vertical prisms of ice, in Quartal 19W P. 487. the same way that the circumzenithal arc is due to the diedral Bollettino Maleuale, Bocieki Mirologiea ItaLium. Torino. Serie 2. Vol.3. angle of at the upper edge of the same prisms. Theory Buti, Giuseype. Applicazione del teorema di Carnot alla circola- 90" zione nell' atmosfera. Pp. 69-72. indicates that this phenomenon only becomes apparent if the Paseerini, -. Sulla '' pioggia di sangue " del 10 marzo 1901. Pp. altitude of the sun is between 59' and 78'. I have not made 73-74. the calculation but, judging from the latitude of the place, the lczelnorie delh Sodeta @li Speffioewpisti Italiani. Catania. Vol. 31. date, ancl the hour, this condition seems to me to have been Boccara, Vittorio E. La '' Fata Morgana " studio storico scien- tifico con appendice bibliograflca. Pp. 199-218. complied with at the time of Mr. Warren's observation. Was it really a circanihorizontal arc that was seen? This does not appear to me absolutely certain for the following reason. THE FLAINFALL OF AMOY, CHINA. When the sun is very high in the sky the halo (of is very By JOHNH. FEJLER,United States annul, dated Amoy, October 25, 190% 46') nearly parallel with the horizon, it would be absolutely so The autumn rice crop in this province bids fair to be almost with a zenithal sun, and if an arc extending only a short dis- an entire failure, owing to the extremely small amount of rain tance froni the lower part of this halo is seen, its parallelism which has fallen. with the horizon may seem to be perfect, especially if the arc The rainfall at this port, it is interesting to note, has shown is broad. Thus, according to the description given by the a steady decrease for the past six years, as is shown in the observer, the arc seen at Santee was very broad and quite following table: short. It may then be asked if this was not merely the lower Year. I nehes. part of the circle of 4Go ? 1897.. ........................................ 57.75 In the note CpOted above Bravais makes this remark: IC The 1898 .......................................... 46.34 1899.. ........................................ 43.61 circumhorizontal arc is difficult to distinguish from the halo 19oo... ...................................... 38.70 of 46' because the curves have the same direction and are 1901.. ........................................ 36.28 near to each other." This dificulty must, indeed, be very great, 1909 (first eight months) ...................... 86.13 if we niay judge by the difficulty frequently experienced in dis- As the rainfall for the last four months of the gear merages tinguishing short and diffuse circumzenithal arcs from the halo not to exceed 2 inches, the total for 1902 will probably be less of 86', even although in this case the curves be in the contrary than 30 inches. direction. It does not, therefore, seem to me to be possible to Unauthenticated | Downloaded 09/26/21 05:33 AM UTC.