These cloud formations are common on the continent, especially in 

 winter, and are found outside the regions of disturbances, or on their 

 extreme lateral edges. 



The layer of stratocumidus may often be broken up; code (7^=5 is 

 used only for those sheets of stratocumidus that are not formed from 

 cmnulus; otherwise they are coded (7^ = 4. The observer may be in 

 doubt between 6^ = 5 and 0„ = 3; the code 0^ = 5 is used only when 

 the stratocumidus is fairly low and rather like stratus (large and rather 

 diffuse tesselations or waves) ; if it is clearly high up and related to 

 altocumulus it is coded Cm = 3. 



6. Low Broken Up Clouds of Bad Weather (15, 16, 17). 



The following is the ordinary course of formation of these clouds: 

 When a veil of altostratus becomes lower, and tends to turn into 

 nimbostratus, it usually has below it a gradually increasing layer of 

 fractocumulus or fractostratus ; these clouds are isolated at first. 

 They ultimately fuse together into a continuous sheet; but through 

 interstices the veil of relatively light higher cloud may be seen (16). 

 The continuous rain does not usually occur until after the formation 

 of the fractostratus or fractocumulus, wliich is then hidden by the 

 precipitation, or may even disappear imder its influence. 



This type is found in the middle of a typical disturbance. 



For the difference between the fractocumulus of bad weather and 

 that of fine weather see the explanation under Ci, = 2. 



7. Cumulus of Fine Weather and Stratocumulus (18, 19). 

 Cumulus clouds may form below an already existing sheet of strato- 

 cumulus, which they do not penetrate. 



Before the formation of the cumulus, the layer of stratocumulus 

 would have been coded 0^ = 5 or C.,i = 3 according to its height. 



If the cumulus penetrates the stratocumulus layer it must be 

 coded Ci = 8. 



8. Heavy or Swelling Cumulus, or Cumulonimbus, and Stratocumulus 



(20, 21). 



Heavy or swelling cumidus, or cumulonimbus may form below an 

 already existing sheet of stratocumulus, and some of the cumulus or 

 cumulonimbus may penetrate the layer. 



This is a formation analagous to (7^=7 except that the vertical 

 development of the convection clouds is more marked, so that in the 

 absence of the upper layer they would be coded (7^ = 2 or (7^=3. 



9. Heavy or Swelling Cumulus (or Cumulonimbus) and Low Ragged 



Clouds of Bad Weather (22, 23, 24). 



When a heavy or swelling cumulus or a cumulonimbus nears the 

 zenith it can hide all, or nearly all the sky with its base; the latter may 

 somewhat resemble nimbostratus, but is distinguished from it by its 

 previous history, or by the broken character of the rain, which, in the 

 case in question, falls to the ground in showers, or, if it does not reach 

 the ground, is seen falling from the lower surface of the cloud in wisps 

 of rain or snow called %arga. 



Generally below the base of such a great cloud there is a greater or 

 smaller amount of lower cloud broken up in the manner of fracto- 

 cumulus or fractostratus, these low clouds may sometimes be in the 

 form of a roller, or an arch. 



24 



