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per-coloured light, it denotes a thunder-storm. The 

 Cumulus frequently attends a rising barometer. The 

 Cumulus is uncommon during the winter months. 



The Cumulo- Stratus cloud is most frequent in the 

 spring and summer months. It indicates thunder- 

 gusts, showers of hail and sudden changes of the wind. 

 It is the densest modification of cloud, and as it passes 

 overhead it causes a reduction of temperature. Its form 

 is compounded of the rocky Cumulus, the Cirro- Stratus 

 and Cirro-Cumulus ; its texture is puckered or corru- 

 gated, and before thunder it becomes deeply fringed, so 

 that it appears to touch the ground. It forms the basis 

 of great thunder-storms, its electrical character attracting 

 clouds and scud from all quarters of the heavens, which 

 uniting confusedly, constitute that indescribable black 

 mass always antecedent to storms of thunder and light- 

 ning. 



The effect of the Cumulo- Stratus cloud on the mer- 

 cury appears to be to give it a tendency to rise. 



The Nimbus is a modification of the Cumulo-Stratus 

 cloud seen in profile during a shower. Its course can 

 be distinctly traced on land, by the dark mist occa- 

 sioned by the rain then actually falling. The Nimbus 

 is never seen with the barometer at great elevations. 



The rainbow is the lovely attendant of the Nimbus 

 cloud only. 



The Stratus is the cloud nearest the ground. It is 

 formed from the sudden chill of certain strata of the at- 

 mosphere, which condensingthe vapour contained in them, 

 renders it visible in a misty cloud or creeping fog. Calm 



