100 OF THE HALO, CORONA, CHAP. 2. 19. 



HALO.* PI. VI. Fig. 1. Circulus vel Annulus 

 lucidus aream includens, in cujus centra Sol 

 uut Luna apparct. 



By a Halo I understand an extensive lumi- 

 nous ring, including a circular area, in the 

 centre of which the sun or moon appears; 

 whose light, passing through the intervening 

 cloud, gives rise to the phenomenon. Halones 

 are called Lunar or Solar, according as they 

 appear round the moon or sun. Those about 

 the moon are the most common. They are 

 generally pretty correct circles : I once, how- 

 ever, saw a Halo of a somewhat oval figure. 

 Halones are sometimes coloured with the tints 

 of the rainbow.* 



HALO DVPLEX, PI. VI. Fig. 2. Duo An- 

 nuli, in quorum centro communi Sol aut 

 Luna videatur. 



A double Halo is not a very common occur- 

 rence. I have observed, that simple Halones 



* The word Halo, or Halos, is evidently derived from the 

 Greek aXxv or aAcuf signifying an area. The Latin writers 

 appear to have spoken indifferently of halones, halyses, 

 coronae, circuli, &c. without sufficiently distinguishing be- 

 tween the Corona and the Halo. 



* The coloured Halo is generally seen in a denser kind of 

 cirrostratus. 



