TBi: NATURAL HISTORY OF CLOUl>«, ^^ 



VII. 



The Natural History of Clouds. By Luke HwwaRd, Esq.* 



CLOUD is a visible aggregate of minute drops of 

 water suspended in the atmosphere. 



The word is probably derived from the Anglo-Saxon ceh- EtymologyEnd 

 lob, covered, hidden, the face of heaven beine so in those '^thmtion of 



111 m. 1 • , • the term cload. 



parts where clouds appear. 1 «e same aggregate, which in 



this situation is culled cloud, obtains the name of mist, 

 when seen to arise from the earth or waters; and fog, whea 

 it envelopes and covers the observer. Yet the two Utter, 

 viewed from a greater distance or elevation, present all the 

 appearances of clouds; while these, in their turn, becomp 

 mists and togs, in proportion as we approach and penetrate 

 them. It may be proper, therefore, for the sake of preci- 

 sion, that the term cloud, in philosophical language, should 

 be made a general one, comprehending all such aggregates, 

 however situate. 



It is concluded, from numerous observations, that the Formed of 

 particles of which a cloud consists are always more or less "'op* ^* ^^'ef„ 

 electrified. The hypothesis, which assumes the existence of 

 vesicular vapour, and makes the particles of clouds to be 

 hollow spheres, which unite and descend in rain when rup- 

 tured, however sanctioned by the authority of several emi- 

 nent philosophers, does not seem necessary to the science of 

 meteorology in its present state; it being evident, that the 

 buoyancy of the particles is not ujore perfect than it ought 

 to be, if we regard them as mere drops of water. In fact 

 they always descend, and the water is elevated again only by 

 being converted into invisible vapour. 



Natural History of Clouds. 

 Since the general introduction of accurate instruiiiejRt^ for Prognostka- 

 determining the changes of density, temperature, humidity, JhTrV°o *®*' 



* This valttalile paper was first inserted in Mr. Tilloch's Philosophical 

 Magaxine, and reprinted, with the author's revisions, in Dr. Ree?'s Nevr 

 Cyclopedia, article Ctoyo, from which 1 have copied it, in order that 

 the readers of o»r Journal may more completely understand the iMete* 

 atolsgical Tables, which will in future appear in our vrork. W. N. 



D 2 auci 



