WEATHER. 143 



through air extremely rarefied: and 

 whenever electric fluid passes through 

 air much rarefied, it always produces a 

 white light. 



Q. Why are there sometimes DIFFERENT 

 COLOURS in the aurora borealis, such as yellow, red, 

 and purple ? 



A. Because the electric fluid passes 

 through air of different densities. The 

 most rarefied air produces a white light ; 

 the most dry air, red; and the most 

 damp produces yellow streaks. 



Q. Does the AURORA BOREALIS forbade fine 

 weather or WET ? 



A. When its corruscations are very 

 bright, it is generally followed by stormy 

 moist unsettled weather. 



Q. Why does a HAZE round the SUN indicate 

 RAIN? 



A. Because the haze is caused by 

 very fine rain falling in the upper regions 

 of the air; when this is the case, a rain 

 of 5 or 6 hours continuance, may be 

 expected. 



Q. Why is a HALO round the MOON a sure 

 indication of RAIN ? 



