Figure B-7. Cirrus and cirrostratus often in band 

 converging toward tlie horizon. 



Figure B^IO. (lirrocumiUus. 



Figure B-S. Cirrostratus covering the entire sky 



Figure B-11. Thin altostratus ( semitransparent 

 everywhere) through which the sun or moon can be 

 dimly seen. 



Figure B-9. Cirrostratus not increasing and not 

 covering the whole sliy. 



Table B-2. Descriptive terms of WMO Code 0500 for 

 recording cloud type (genus) 



Name of Cloud Type Abbreviation 



Cirrus Ci 



Cirroeumulus Oc 



Cirrostratus Cs 



Altociunulus Ac 



Altostratus As 



N'imbostratus Ns 



Stratocumulus Sc 



Stratus St 



Cumulus Cu 



Cumulonimbus Cb 



Clouds not visible owing to darkness, fog. 



du.ststorm, sandstorm, or other analogus 



phenomena. 



Figure B-12. Thick altostratus or nimbostratus. 



active vertical mixing, which in turn tends to 

 disperse haze or fog particles that may have 

 accumulated at low levels. An unstable atmos- 

 phere is characterized by cumulif orm clouds and 

 a showery type of weather. 



On the other hand, when the sea temperature 

 is lower than the air temperature, it follows that 

 the sea cools the lowest layers of the atmosphere. 



B-5 



