made only when a kite flight or a pilot balloon observation was 

 practicable. With very low clouds in summer, the kites became 

 iced and were forced down so that, in general, measurements of 

 the ceiling could not be made. From other sources it is indicated 

 that the height of stratus clouds is frequently found between 600 

 and 1,000 feet. Stratocumulus may be expected most frequently 

 at around 5,000 feet ; and, as mentioned previously, they are more 

 frequent over the coast than over the sea. Altocumulus have an 

 average height of 10,000 feet and altostratus about 13,000 feet. 

 The various types of cirrus clouds are encountered between 15,000 

 and 30,000 feet. 



CEILINGS 



The average height of the various types of clouds has been noted 



above. Data on ceilings are difficult to find and are not too reliable. 



Low ceilings are most frequent over the Kara Sea area. Over 



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Hgurc 3-11. — Low ceilings over Kara Sea region. 



120 



