m CLOUD. 



iu summer, and u attendant ao warm and dry weather. It may 

 either evaporate or gradually become cirrus or cirro-itratus. 



Cirro-Mratiu. Horizontal or .lightly inclined mieiii, attenuated 

 toward* a part or the whole of their circumference, bent downward, 

 or undulated ; aepante, or in group* consisting of small cloudi having 

 theee character*. This cloud appears to result from the subtidenoe 

 of the fibroi of the cirrus to a horuontal position, at the same time 

 that they approach toward* each other laterally. The form and 

 relative position, when seen in the distance, frequently give the idea of 

 ahoals of fish. Yet in this, aa in other instance*, the structure murt 

 be attended to rather than tho form, which varies much, presenting at 

 time* the appearance of parallel bars, or interwoven streak* like the 

 grain of polished wood. It id thick in tho middle and attenuated 

 toward* the edge. The cirro-stratus precedes wind and rain, the near 

 or distant approach of which may sometimes be estimated from its 

 greater or lea* abundance nnd permanence ; it is almost always to be 

 seen in the interval* of storms. Sometimes this and the cirro-cumulus 

 appear together in the sky, and even alternate with each other in the 

 same cloud, when the different evolutions which take place are a 

 curious spectacle, and a judgment maybe formed of the weather likely 

 to ensue by observing which modification prevails at last. The cirro- 

 tratua is also, as indicated under Vimu, the modification which most 

 frequently and completely exhibits the phenomena of the solar and lunar 

 halo, and also the parhelion and paraselene. Hence the reason of the 

 prognostic of foul weather commonly drawn from the appearance of halo. 



The compound modifications are : 



C*m*Jo-ttraliLt. The cirro-stratus blended with the cumulus, and 

 either appearing intermixed with the heaps of the latter, or superadding 

 a wide-spread structure to its base. " This," remarks Sir J. Herschel, 

 " would seem to be the modification of cumultu, when the columns of 

 rising vapour which go to form it arrive in an upper atmosphere not 

 sufficiently dry to round off its summits by rapid evaporation, allowing 

 them to spread horizontally and form flat-topped, mushroom-shaped 

 manes; the upper parts of which are often curled by the wind of an 

 upper current into cirrous wisps, or cleanly cut off by a horizontal 

 plane, forming an ' anvil-shaped cloud,' with a lateral projection, gene- 

 rally considered as a precursor of wind below. Its tendency is to 

 spread, overcast the sky, and settle down into the nimbiu," which 

 finally falls in rain. 



" When," according to Mr. Howard, " a whole sky is crowded with 

 this modification, the appearances are indistinct. The cumulus rises 

 through the interstices of the superior clouds ; and the whole, wen as 

 it piMM off in the distant horizon, presents to the fancy mountains 

 covered with snow, intersected with darker ridges, lakes of water, 

 rock*, and tower*, Ac. The did! art cumulo-stratus is formed in the 

 interval between the first appearance of the fleecy cumulus and the com- 

 menoement of rain, while the lower atmosphere is yet dry ; also during 

 the approach of thunder-storms ; tli appearance of it is chiefly 



in the longer or shorter intervals of showers of rain, snow, or hail." 



Nimbiu, or Cumulu-cirm-ttratiu. The rain-cloud. A cloud, or sys- 

 tem of clouds, from which rain is falling. It is a horizontal sheet, 

 above which the cirrus spreads, while the cumulus enters it laterally 

 and from beneath. It is the lowest of clouds next to the stratus. 

 Cloud* in any one of the preceding modifications, at the same 

 degree of elevation, or in two or more of them at different eh 

 may increase so a* completely to obscure the sky ; and may at 

 time* put on an appearance of density, which to the inexperienced 

 observer indicate* the speedy commencement of rain. " It U never- 

 theless extremely probable," Mr. Howard states, "as well from 

 attentive observation as from a consideration of the several modes of 

 their production, that clouds, while in any of these states, do not at 

 any tune let fall rain. Before this effect takes place, they have been 

 uniformly found to undergo a change attended with appearances 

 sufficiently remarkable to constitute a distinct modification. These 

 appearances, when the rain happens overhead, are but imperfectly 

 awn. We can then only observe, before the arrival of the denser and 

 lower clouds, or through their interstices, that there exists at 

 altitmdt a thin light veil, or at least a hazy turbidness. When this has 

 considerably increased, we see the lower clouds spread themselves till 

 they unite in all point* and form one uniform sheet. The rain then 

 commences; and the lower clouds, arriving from the windward, move 

 under this sheet, and are successively lost in it When the latter cease 

 to arrive, or when the sheet breaks (letting through the sunbeams), every 

 one'* experience teachen him to expect an abatement or conation of 

 Me ram. But there often follows, what seems hitherto to haye been 

 unnoticed, an immediate and great addition to the quantity of cluwl. 

 At the name time the actual obscurity i* lessened, because the arrange- 

 ment which now returns, gives freer passage to the rays of light ; for 

 on the crmation of rain, the lower broken clouds which remain riw 

 into cumuli, and the superior sheet puts on tho various forms of the 

 ofaro-atnttw, sometime* passing to the cirro cumulus. .... 1 i - 

 nimbtu, although in itself one of the least beautiful clouds, U yet now 

 and then superbly decorated with it* attendant the rainbow : which in 

 wan in perfection when backed by the widely extended uniform gloom 

 of thin modification.'' 



Further particulars of all tho modifications of cloud, and their con 

 Motion with the weather, and with other atmospheric phenomena, wil 

 b found in Mr. Howard's work. In the Meteorological Observations 



CLOUD. MO 



made at the Koyal Observatory, and auuu . the ' < ireeii- 



wich Observations,' as stated iu tl .loud* and 



weather are described generally by II--... mi Noin.-i 

 owing notation being used for tin former : <-i rirntt, ci-eii. cirro-rumulm, 

 ci-s. rtrrv-itraliu, cu. rumu/iu, cu-s. 



The only adjective*, we may add, which have been formed from these 

 name* are " oil-rose " and " cirrous," identical in sign which 



the Utter i* generally employed. 



Hear- Admiral Robert Fitz Hoy, F.R.S.. now Superintendent of tin 

 Meteorological Department of the Board of Trade, n hi- 



Appendix (published in 1889) to vol. ii. of the ' 



veying Voyages of H.M.S. Adventure and Beagle,' the latter :' which 

 le commanded, and in which, besides examining the southern shores 

 at South America, he circumnavigated the globe, has given, pp. 275-6, 

 ind illustrated in four plates, a modified classification and nomenclature 

 of the Clouds, in which he has in one direction contracted those 

 Howard, and in another greatly extended them. Substitute 

 jerm " class " for " modification," he divides clouds into four classes, 

 ' cirrus, stratus, nimbus, cumulus ;" thus regarding the nimbus, whk-h 

 Mr. Howard considers to be compounded of the other three, 

 equal rank in the classification with each of them as it were aa a simple 

 modification. Adopting Mr. Howard's terms for the intermediate and 

 compound modifications (but, with a want of precision often 

 vable in those meteorologists who have in a general manner f] 

 turn, ascribing to the former the character of being mixture* of simple 

 modification*, which is true only of the latter), Admiral Fit/roy adds, 

 ' Which terms may be rendered more explanatory of the pr. . :- kind 

 of cloud by using the augmentative termination ontu, or the diminu- 

 tive, it in. Thus: cirronus, cirritus; curono-utratus, cirrito-stratus ; 

 cirrono-cumulus, cirrito-cmuulus ; stratonus, stratitns; cumu 

 cumulitus; cumulouo-stratuB.cuinulito-stratus. Should the*.: l,c found 

 insufficient," he continues, " to convey distinct ideas of every 

 of clouds, the second word may be augmented or diminished 

 cirrono-stratitus," &c. Hcalso partially adopts an KngEsh nomenclature 

 for his classes of cloud, which had first been proposed some years after 

 the publication of Mr. Howard's paper ; thus : curl-cloud, Hat-cloud, rain- 

 cloud, heap-cloud. But, as Mr. Howard had remarked (' I'lim. uf Lond." 

 first edit. voL i. p. xxxii.) the English words employed do not fully 

 denote the ideas expressed by the Latin terms he had given, which 

 have the further advantage of being adapted for use in all countries. 

 And accordingly, although half a century has elapsed since the first 

 _estion of the English terms, and twenty years since its revival by 

 Admiral Fitz liny, meteorologists and other observers have continued 

 to employ Mr. Howard's original designat 



It may be doubted, also, whether the extended nomenclature iu 

 Latin proposed by Admiral Fitz Boy, would not, if adopted, 1 

 rather an incumbrance than a benefit. Frequent observation of the 

 clouds for a considerable period, and for several years under tl 

 sonal correction of the author of the original nomenclature himself, 

 I to the present writer to justify him in the opinion, that if tho 

 additional denominations are to be regarded as expressing only the 

 increased or diminished magnitude of the several modifications as 

 witnessed, they are unnecessary, it being better to use ordinary 

 live language for tho purpose ; and that, if they be regarded as 

 describing minute variations in the aspect of the clouds, they involve 

 an attempt minutely to define that which is too irregula. 

 tain to be made the subject of formal science. The examine 

 the figures given in the plates confirms this opinion ; but it may be 

 admitted on the other hand, that Admiral Fitz Hoy has ol 

 clouds over a greater area of the globe, in longitude and latitude, than 

 most other meteorologists who have attended to them, and t i 

 objection similar to the last has been made at various periods to 

 Mr. Howard's classification itself. The sufficiency of this, hot 

 appears to have been established by the judgment of meteorologist* in 



i . the only one who h.i* even partially adopted I 



as far awe are aware, bcin^ Professor C. Piazzi Smyth, and lie, in his 

 t\-,o \\orks on the Teueriffe Astronomical Experiment, has n 

 tin- augmented term cumuloni to Mr. Howard's original design, 

 while he is known to have recorded his experience of their . . ( u.,l a|i]>li 

 cability, also, in climes ao different and no distant i 

 well an i M South Africa and Qreat I'.i 



Sir .1. K. W. ll.rschel, whose observation* of the heavenly 

 have led him to give constant attention to the processes goiiiK on in the 

 i through which they are necessarily viewed, has recorded iu his 

 memoirs of special astronomical or other observations, and philosophi- 

 cally considered in his more general treatise*, many of the more 

 important phenomena of the cloud*, which he has treated iu a very 

 original manner, evolving, we believe, some comprehensive trutl 

 which ' : - ' ' ' ' ' ' 



Knows, in the article ' Meteor 

 clopndia Britannica ' ( i > 

 raoten of certain mo' 



of vapour is generated from any v 



by it relative levity, losing K 



by its bodily trail- I im 



the sujiply <-i \apom, hou, ,. r. not be very copious, and should 



itself m its ascent always iu a region hygrometrically dry, it by no 



mean* follows that it will reach the point of precipitation; but should 



ally indebted to him. Thus he 

 the eighth edition of the 



the additional cha- 

 l body 



'ting surface, it ascends 

 t, at well by its own expand m a*, 

 with colder air. Should 



