534 



METEOROLOGY. (CLOUDS.) 



be afforded by the burning of 31,000,000 tons of 

 coal. Most of this heat is dispersed in the at- 

 mosphere of the valley during the cold season, to 

 make the falls and winters milder. 



The climatological tables of the British Em- 

 pire, published in Symond's " Monthly Meteoro- 

 logical Magazine," go to show tnat the extremes 

 are monopolized year after year by the same sta- 

 tions. For the last five years Adelaide, South 

 Australia, has recorded the highest temperature 

 in the shade, which was 109 in 1887, and 

 reached 112-4 in 1886. The same place had also 

 the highest temperature in the sun, 170*7, and 

 was the dryest station during 1889, having a 

 mean humidity of 63 per cent. The lowest shade 

 temperature in 1889 was recorded at Winnepeg 

 on Feb. 23, 42'6. Once only did any station 

 come within 20 of this. Winnepeg also exhib- 

 ited the greatest range in the year, the greatest 

 mean daily range (24-5), the lowest mean tem- 

 perature, and the least rainfall (14-96 inches). The 

 highest mean temperature was 80-5, at Bombay ; 

 and the greatest rainfall, 73'79 inches, at Trini- 

 dad. London was the most cloudy and the damp- 

 est station, the mean humidity being 81 per cent. 

 The brightest station was Malta, which had lit- 

 tle more than half the cloud of London. 



Clouds. Prof. Abbe has elaborated a nepho- 

 scopic method for determining the actual height 

 and velocity of clouds by combining observations 

 made when the vessel or observer moves succes- 

 sively in two different ways, or with two different 

 velocities. It is called the "aberration meth- 

 od," in distinction from ordinary parallax meth- 

 ods. Prof. Abbe's main work has been a deter- 

 mination of the motions of the atmosphere from 

 a study of the lowest winds and the successive 

 strata of clouds. The visible clouds, he con- 

 cludes, give little or no information as to the 

 motions of the atmosphere in the widest sense, 

 but prove that it is everywhere divided into 

 local systems of currents, so that we have winds 

 circling around a storm center, a high barom- 

 eter, an ocean, or a continent ; and, at least 

 on the Atlantic, no winds that circulate ex- 

 actly as they would do on a rotating, uniform, 

 smooth globe. The angles of inflow and outflow 

 have been determined for three or four succes- 

 sive strata of air in mid-Atlantic ; also the rela- 

 tions of the cloud-appearances to distant storms, 

 squalls, rains, and changes of wind, with such 

 accuracy that on many occasions predictions of 

 such phenomena have been made and verified. 



A fuller description than has been published 

 before of the luminous clouds observed in the 

 evenings of midsummer is given by O. Jesse, of 

 Steglitz, near Berlin. The phenomenon was first 

 remarked by the author on the 21st of June, 1885, 

 at about 9.50 P. M., when the northwestern and 

 northern sky was covered to the height of about 

 20, with a layer of bright cirrus-like clouds, which 

 reached from about northwest to north-northeast. 

 Three horizontal zones were distinguished, the 

 lower one of which was without luster, and yel- 

 lowish. Higher up was a strip, several degrees 

 in breadth, " which shone with an extremely beau- 

 tiful, white gleaming, silver-like light." Above 

 this strip was another like it, but not quite so 

 brilliant, of a bluish tint. The light of the cen- 

 tral zone was comparable with that of the near- 

 ly full moon at sunset. About 10.30 P. M. the 



height of the upper limit of the phenomenon 

 had been somewhat reduced. The sun was 

 through all the time of this observation which 

 was made in 52 5' north latitude at a depth be- 

 low the horizon at which ordinary clouds can 

 not any longer be affected by its direct light. 

 The phenomenon reappeared several times in the 

 course of the following weeks, beginning fifteen 

 or twenty, or sometimes forty minutes or more, 

 after sunset, sometimes covering nearly the whole 

 sky, and being marked by a gradually increasing 

 brilliancy which was accompanied by a progress- 

 ive extinction of the phenomenon proceeding 

 from southeast to north-northwest. Toward the 

 end of July the luminous clouds disappeared. 

 The phenomenon presented itself again, sudden- 

 ly, toward the end of May, 1886, and remained 

 visible, with some interruptions, till the begin- 

 ning of August. It has been repeated since 

 from year to year, always at the same season. 

 Mr. Jesse has determined that the luminous 

 clouds migrate in such a way that they may be 

 found in the southern hemisphere between the 

 forty-eighth and sixtieth degrees of latitude dur- 

 ing December and January ; but he has received 

 no information of the phenomenon being -ob- 

 served in the equatorial regions. The gradual 

 extinction of the upper limits of the luminosity 

 with the deeper sinking of the sun indicates that 

 the phenomenon is an effect of direct illumina- 

 tion. Different measurements gave from 50 or 

 60 kilometres to 81 or 82 kilometres as the 

 height of the clouds. 



A similar phenomenon has been observed by M. 

 Ceraski, of the Moscow Observatory, since 1885, 

 whose observations are in substantial agreement 

 with those of Mr. Jesse as to the season and the 

 time of night at which the clouds appear, and 

 as to the height of the clouds. The phenom- 

 enon of green clouds was witnessed by Will- 

 iam Ogilvie while on the the upper Yukon, Feb. 

 19 and 29, 1888. It was seen in the morn- 

 ing, just before sunrise, and on both occasions 

 the sun was covered with downy white clouds, 

 while there was a very slight fall of minute ice 

 crystals, accompanied by a much higher temper- 

 ature than usual. The color was a brilliant em- 

 erald green, fringed on the lower side with yel- 

 low, which, as the sun gradually rose encroached 

 on the green, until the clouds were all yellow. 

 This color changed to orange and red after the 

 sun had risen above the horizon. 



The formation of a tornado cloud was wit- 

 nessed in Minneapolis, Minn., on July 14th. 

 The process was thus described in the " Journal" 

 of that city: "First, there was a concentration 

 of clouds at a certain point from all directions 

 all rushing together with great velocity. As 

 detached clouds came in contact with the con- 

 centrated masses, they would be seized upon by 

 an invisible power and hurled downward with 

 terrific force, but all the time the central cloud 

 grew more and more dense, until it became a 

 black and impenetrable mass." 



The observations respecting the number of 

 dust particles in the atmosphere made by Mr. 

 Rankin with apparatus invented by Mr. Aitkin, 

 at the Ben Nevis Observatory, Scotland, point, to 

 a daily maximum during the afternoon mini- 

 mum barometer, and a minimum during the 

 morning minimum barometer. Relations are in- 



