Cloufc formation. V3 



as the sun lowers in the west and the heated 

 air becomes more evenly distributed this con- 

 densed vapor is re-absorbed into the air as in- 

 visible moisture by a process allied to that of 

 evaporation. This condition of things would 

 extend to a much longer period than it does in 

 our latitude if it were not for the gradual 

 changing of the seasons, which finally destroys 

 the balance in the dynamics of cloud-land and 

 allows the cold that has been held back for 

 the time in the great northern zone to get 

 the upper hand. Then we have what is termed 

 in common parlance a change in the weather, 

 or, more properly in this case, a change in the 

 season. 



We have already spoken of the cloud called 

 cumulus (which means heap) and of its per- 

 formance during the dry season of summer. 

 There is another form of cloud that is seen at 

 this season of the year called cirrus (a curl). 

 It takes the form of a curl at its ends. This 

 cloud usually has a threaded shape and some- 

 times takes the form of a feather, and fre- 

 quently forms are seen that remind you of 

 frost pictures on a window pane. These 

 clouds float very high in the atmosphere, 

 away above the tops of the highest moun- 

 tains, from six to eight miles above the 

 level of the sea. They are formed only at a 

 season of the year when the atmospheric con- 

 ditions are most uniform. At certain times 



