CLIMATIC CHARACTERISTICS 



131 



Figure 4.34. Yearly mean and range ratio of AN. 



this locale. In the lowest layers of the atmosphere warm, moist air from 

 the Mediterranean Sea is advected inland underneath superheated air 

 from the Sahara Desert. Along the zone of contact between these air 

 masses of widely differing moisture content, spectacular drops in vapor 

 pressure and, consequently, in the wet term component of A'^ occur. 

 During the winter, moderate temperatures and prevailing offshore flow 

 combine to produce near-normal gradients of N. Consequently the 

 summer-to-winter AiV ratio turns out to be quite high for this borderland 

 station. 



The analysis above represents a rough and crude first attempt to under- 

 stand the climatic variations of N . It is expected that such classifica- 

 tions will improve with the addition of data from more diverse locations 

 and, in particular, as our knowledge of the role of water vapor in climatic 

 variability increases. 



