THE SEASON WHY. 93 



'Who giveth rain upon the earth, and sendeth waters upon the fields." 

 JOB y. 



1. The Cirrus (Fig. 5), estimated range of altitude from 10,000 

 to 24,000 feet. 



2. The Cumulus (Fig. 7), from 3,000 to 10,000 feet. 



3. The Stratus, an extended continuous level sheet of cloud, 

 increasing from beneath. They fly very low. 



4. The Nimbus (Fig. 10), 1,500 to 5,000 feet. 



5. The Cirro-cumulus (Fig. 4), from 3,000 to 20,000 feet. 



6. The Cirro-stratus (Fig. 6), from 5,000 to 10,000 feet. 



7. The Cumulo-stratus (Fig. 9), from 3,000 to 10,000 feet. 



CIRRO-STRATUS, OK WANE CLOUD. 



The estimated heights given must be looked upon as very conjectural, 

 although they have been derived from the best existing authorities. It is sufficient 

 to know that the range of the altitude of the various clouds is from that of the 

 Nimbus, or thunder cloud, 1,500 feet, to that of the Cirrus, 24,000 feet, the 

 others being intermediate. The first three of the clouds above enumerated 

 constitute what are called the primary forms. The remaining four are called 

 secondary forms, because they arise, as their names generally indicate, out of 

 combinations of the primary forms. Although, from the frequent mingling of 

 clouds, it is not always practicable to identify them by the adopted classification, 

 still, as there is generally a prevalence of one type of cloud over another, the 

 observer would be able to distinguish a " Cirrus sky," or Cirro-cumulus sky," &c. 

 Upon some -occasions the typical characters of the clouds are beautifully 

 defined; and the contemplation of their forms, and the laws of their formation, 

 affords infinite pleasure to the observer. The advantages of scientific knowledge 

 are such, that whether you look downwards to the earth, or upwards to the sky, 

 you have still the writing of God to read. 



380. What produces the various shapes of clouds t 



1. The state of the atmosphere. 



2. The electrical condition of the clouds. 



3. The movements of the atmosphere. 



4. The season of the year. 



