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The occurrence of overcasts decreases regularly during 

 the period until in November and December, only 4 mornings a 

 month are overcast. The extent of summer sea fogs also dimi- 

 nishes rapidly after October and during the later months of 

 the year, most cloudy conditions are the result of infrequent 

 frontal storms „ The number of days with a broken sky increases 

 slightly, the clouds being the remnants of the morning fogs. 



The most striking climatic characteristic is the great 

 increase of days with clear skies in October, November, and 

 December. These conditions reach a maximum in November when 

 55% (21 days) of the month is clear all day long. This, with 

 the 67% of the clear afternoons in December, indicates the 

 fine weather to be expected in these two months. 

 Haze 



An important and common deterrent to visibility over the 

 coastal waters is the haze which precedes and proceeds fog and 

 low stratus clouds. During the summer months in particular, 

 haze is prevalent and thick over the adjacent land mass. Its 

 occurrence cannot be missed due to the brownish tinge contri- 

 buted by the addition of smoke and fumes to the atmosphere. 

 Normally this "smog" does not occur over the ocean, but 

 following several days of smog, a land breeze may carry it 

 seaward. 



The haze results from the stable air conditions, the strong 

 temperature inversion, and the geography of the Los Angeles 

 region. Turbulent unstable air masses tend to disrupt the 

 inversion and allow the haze to dissipate. However, the nor- 

 mally stable marine air is held in check by the semi-circular 



