204 RADIATION. 



Q. Why is DEW deposited only on a FINE 

 clear NIGHT ? 



A. Because, when the night is clear 

 and fine, the surface of the ground 

 radiates heat most freely ; and (being 

 cooled down by this loss of heat) chills 

 the vapour of the air into dew, 



Q. Why is there NO DEW on a dull CLOUDY 

 NIGHT ? 



A. The clouds arrest the radiation 

 of heat from the earth; and (as the 

 heat cannot freely escape) the surface is 

 not sufficiently cooled down to chill the 

 vapour of the air into dew- 



Q. Why is a CLOUDY NIGHT WARMER than 

 a FINE one ? 



A. Because the clouds prevent the 

 radiation of heat from the earth; and, 

 therefore, the surface of the earth 

 remains warmer on a dull cloudy night. 



Q. Why is DEW most ABUNDANT in situations 

 most EXPOSED ? 



A. Because the radiation of heat is 

 not arrested by houses, trees, hedges, or 

 any other thing. 



Q. Why is there scarcely any DEW under a 

 shady TREE ? 



