COLOURED KAYS. 399 



A. As the bubble is suspended, the 

 water keeps running down from the top 

 to the bottom of the bubble, till the crown 

 becomes so thin as to burst. 



Q. Why are the late EVENING CLOUDS RED ? 



A. Because RED rays (being the least 

 refrangible) are the last to disappear. 



Here it will be seeii that the red ray PA, being 

 reflected on the horizon at A, will be visible to us; but 

 the YELLOW and BLUE rays will be hidden by the curve 

 of the earth. 



Q. Why are the early MORNING clouds RED ? 

 A. Because RED rays (being the least 

 refrangible) are the first to appear. 



See last figure. It is evident that P A (the red rays) 

 will be reflected on the horizon before either the yellow 

 or blue ones. 



Q. What becomes of the BLUE and YELLOW 

 rays ? 



Ma 2 



