CLOUD WINDS 203 



XII 



THERE are some species of winds which issue i 

 from clouds that are rent and pour down their 

 contents. They are called by the Greeks cloud 

 winds (e'/>e</>ta<?). Their method of formation, as 

 I suppose, is this : among the particles given off 

 by the earth's vapour and carried aloft there is great 

 inequality and dissimilarity, some being dry and 

 others moist. When the particles have massed in 

 one body there is great discord and internal strife, 

 which probably leads to the forming of certain hollow 

 clouds with narrow pipe-shaped spaces left between, 

 much like a flute in shape. In these gaps there 2 

 is shut up rarefied air, which, being buffeted about 

 in the confined space and becoming heated, strives to 

 get more room. It expands and rends its envelope, 

 breaking forth in wind, which, as a rule, is squally, 

 since it descends from above and falls on us with 

 fierce vehemence. It is not diffused, nor does it 

 come through a wide open space, but it struggles 

 and opens up its way by main force. As a rule, it 3 

 is a brief gust. As it bursts through the cloudy 

 receptacle by which it was confined and overleaps 

 the battlements, it comes in tumultuous energy, 

 sometimes not unattended with fire and the sound 

 of thunder in the heavens. Such winds are much 

 more violent and of longer duration if they have 

 taken up in their course other gusts proceeding 

 from a like cause, and thus several have conspired 

 to form one. It is just like the flow of torrents of 

 moderate size, not serious as long as each has its 

 separate course. But when a number of them have 4 



