V4 feature's ASfracles. 



of the day and night the moisture will rise to 

 this height before it condenses and when it 

 does condense it immediately freezes, which 

 makes it take on these peculiar forms that 

 would no doubt conform very closely to the 

 frost pictures on the window pane if it were 

 not for the disturbing influences of air cur- 

 rents at this altitude. The fact that they are 

 ice or frost clouds instead of water clouds 

 gives them that peculiar whiteness and bright- 

 ness of appearance. If ordinary clouds are 

 water-dust these high clouds may be called ice- 

 dust. Sometimes we see them lying in bands 

 or threads running across the sky in the di- 

 rection that the wind blows. Their form is 

 undoubtedly a resultant of the struggle be- 

 tween the air currents and the tendency of 

 crystallized water to arrange itself in certain 

 definite lines or forms. This cloud may be 

 said to be one extreme, having its home in 

 the highest regions of cloud-land, while the 

 cumulus, or thunder cloud, is the other ex- 

 treme and occupies the lower or mid regions 

 of the air. 



There is a still lower cloud of course, as 

 ordinary fog is nothing more than cloud, 

 which under certain conditions lies on the 

 surface of the ocean or dry land. Fogs pre- 

 vail when the barometer is low. As soon as 

 it rises from the source of evaporation the 

 moisture condenses almost to the point of pre- 



