CONCERNING THUNDERSTORMS— II 



By WILLIAM J. S. LOCKYER, M.A., Ph.D., F.R.A.S. 



ALTHOUGH I am interested both in 

 J~\ ballooning and thunderstorms. I 

 prefer not to study them simul- 

 taneously, and would advise others to do 

 the same. Thunderstorms spoil all the 

 pleasure and fascination of balloonmg. be- 

 cause when one wishes to take an aerial 

 trip the conditions are best when the wind 

 is steady in one direction. This is not 

 the case \\hen a thunderstorm is in the 

 neighbourhood. There is either no wind 



have been obser\-ed by man e\'er since 

 he walked on the earth, but it was not 

 till Franklin's time, in 1752, that we 

 were taught that lightning was identical 

 with the electricity that can be artificially 

 produced. Frankhn proved this by tap- 

 ping the electricity under a thunder-cloud 

 by means of a kite, using the cord of the 

 kite as a conductor to bring the electricity 

 to earth. 



A lightning flash may be looked upon as 



or it is liable to change its direction any the result of a great electrical disturbance 



moment, and flashes of lightning playing between masses of vapour condensed in 



around are not desirable companions our atmosphere in the form of clouds, 



when one is supported by an envelope that part of the earth's surface which lies 



full of inflammable gas ! Further, m 

 the front of a thunderstorm there are up 

 currents which are far from desirable 

 when one is in such a craft, and it was 

 my fate on the occasion of my first 

 balloon trip to be in such a current. 

 This occurred on June 29, 1907, when a 

 passenger in one of the balloons com- 

 peting in an Aero Club long distance race. 

 A \'iolent thunderstorm was nearh' 

 over us as we ascended, and we expected 

 10 attain a certain altitude in accordance 

 with our "lift." But this was by no 

 means the case actually, for we found 

 ourseh'es in a current directed from the 

 earth, which not only sent us up an extra 

 2,000 feet, but was strong enough, before 

 the balloon responded to the ascending 

 current, to blow upwards into the basket 

 of the balloon a large square of cahco 



immediately below these masses, and the 

 intervening air space. 



Perhaps the most difficult question to 

 answer is " How is the electricity pro- 

 duced ? " Electricity is undoubtedly 

 formed in our atmosphere, but whether 

 it is the result of condensation of water 

 vapour, or caused by evaporation, or by 

 wind, or any other means, it is difficult 

 to sav. Its origin is generaUy attributed 

 to condensation in the following manner. 

 Electricity, it must be first understood, 

 onlv resides on the surface of a body. 

 Each minute particle of a cloud has a 

 small electric charge distributed over its 

 surface. \\'hen condensation takes place 

 these particles coalesce and form rain- 

 drops. The surface of one raindrop being 

 less than the combined surfaces of all 

 those of the particles of which it now 



which was suspended from the side of the forms part, there must be more electricity 



basket. At about 5,000 feet we somehow 

 became free of this current, and natur- 

 ally began to fall with considerable 

 rapidity, which was only checked by the 

 bountiful discharge of ballast 



per unit area on the raindrop than there 

 was on each particle. The consequence 

 is that the electrical potential of the 

 raindrops increases with condensation. 

 The greater, therefore, the raindrops, 



Now perhaps the most important feature the more hea\-ily laden becomes the cloud 



of a thunderstorm is the electrical phe- and the darker it appears, 



nomcna connected with it. and naturally With this ever increasing store of 



these are best seen when the storms occur electric energy on the cloud it is certain 



after the sun has set. Lightning flashes that a limit must soon be reached, and 



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