The Cause of Rainfall.

Auckland Star, Volume XXVII, Issue 283, 28 November 1896, Page 2 (Supplement)

The Cause of Rainfall.

Hats' is, as we all know, tho moisture of tho atmosphere condensed into drops largo snough to fall with perceptible velocity to :he earth. The variation in tho sizes of the jrops is dependent upon tlio diflorenco in tho height: from which they have fallen and in tho amount of atmospheric disturbance present ab the time. If they fall from jreafc heights the drops sufior gradual division into smaller anil smaller puts, until ;hey are ab last converted into amis. In jalm weather, with the clouds near tho iarth's surface, the drops aro apt to be argo and heavy. The formation of am i?, in general, a continuation or in enlargement of tho processor )y which clouds and fogs are ormed. The deposition of moisture dojende upon the cooling of tho atmosphero, >ut, concerning the precise process by vhieh tho cooling ia efl'ected, various ipinions are entertained, even among those yho bavo made meteorology a life r"tudy. n considering the matter we havo deduced iur reckonings, from what is coruiiieied t,he ieeß authority'on the subject. Fr«.n this b appears thai; the temperature of a given naas of warm air is lowered, in the ordinary ourse of atmospheric phenomena, by nna r the other of the processes mentioned i.) ho following:—By radiation :o the cold ky ; by radiation to tho noiuhboujing lasses of clouds or the cold ground ; by aixturo with cool air, or by the absorption f heat in the expansion of ascending olumns of air. Whatever tho process may c, one thing in sure—the cooling mu«fc iko place before the moisture v/ili collect >to drops of sufficient size to causo thorn j ) fait from the mas« of vapour in which 1 '>i j snstiSuont parts have been floating. ,