CONCERNING THUNDERSTORMS 



619 



precedes the storm, and may be from 

 ten to fifty miles ahead of it. As time 

 passes, imderneath this layer will next 

 be observed thick dark grey and violet 

 coloured clouds of the cumulo-stratus 

 type, and after that grey or ruddy clouds 



For some time rain continues to fall in 

 great abundance ; but the times of greatest 

 rainfall vary, sometimes being near the 

 beginning and sometimes toward the 

 end of the storm. 



Behind the storm the horizon now 



at a still lower ele\'ation. The approach becomes lighter, clouds in that region are 

 of the main cloud of the storm will now seen detached, and later on blue sky is 

 be seen in the distance, and as these low visible once more. The rain ceases as 

 clouds begin to pass overhead, they are the last of the storm-cloud passes over- 

 seen to be 

 rounded under- 

 neath and to 

 have a billowy 

 appearance. 

 The wind be- 

 gins to rise in 

 strength, a n d 

 the direction 

 from which it 

 blows becomes 

 reversed. The 

 wind now takes 

 the nature of a 

 squall ; but this 

 is short-lived, 

 and is followed 

 by a deluge of 

 rain. Already 

 distant light- 

 ning has been 

 dimly seen, and 

 thunder heard ; 

 but the storm 

 now bursts over 

 the position of 

 the observer. 



'ITS EXTREME WHITENESS . . . RENDERS IT A STRIKING OBJECT." 

 An embryo thunder-cloud photographed by Dr. Lockyer at South Kensington in 1906. 



and is accompanied by numerous bril- 

 hant flashes and the loudest of thunder 

 claps. The flashes, owing to the fact 

 that it is still day-time, do not, how- 

 ever, appear so intensely bright as they 

 would if the storm had taken place at 

 night 



head. The landscape now emerges from 

 gloom to light, the air feels fresher, the 

 temperature, which has been lowered, rises 

 again, and once more serenity prevails. 



Thunderstorms, when they come singly, 

 do not last very long, the length of time 

 between the first and last sounds of 



The moment of the bursting of a thunder being on an average about two 



hours. Very often, howe\'er, thunder- 

 storms occur in series, and when one is 

 over another follows in its wake. In 

 some regions. gencraUy owing to the 

 peculiar configm-ation of the surrounding 

 country, the thunderstorm recurves and 

 passes over the same locality again. 



Ha\-ing now recalled to memory the 

 general features connected with the 

 approach and departure of a " grown 

 up " thunderstorm, let us now consider 



thunderstorm is well expressed in the 

 following hues from the " Ingoldsby 

 Legends" :— 



■" And then a hollow moaning blast 



Came, sounding more dismally still than the 



la.st, 

 And the lightning flash'd, and the thunder 



growl' d, 

 And louder and louder the tempest howled, 

 And the rain came down in such sheets as 



would stagger a 

 Bard for a simile short of Niagara." 



