AEROGRAPHER'S MATE 3 & 2 



Figure 14-20.— Effect of mountains on a cold front. 



209.67 



its influence. As the lower portion of the frontal 

 surface approaches the range, the underlying 

 cold wedge is cut off, forming a more or less 

 stationary front on the windward side of the 

 range. The inclination of the frontal surface 

 above the range decreases and becomes more 

 horizontal near the mountain surfaces, but the 

 frontal surface maintains its original slope at 

 higher altitudes. While the stationary front on 

 the windward side of the range may be 

 accompanied by prolonged precipitation, the 

 absence of ascending air on the leeward side 

 of the range causes little or no precipitation. 

 The warm air descending the leeward side of 

 the range causes the cloud system to dissipate 

 and the warm front to travel as an upper front. 



Fr ontogenesis (the formation of a new front 

 or the regeneration of an old front) may occur 

 in the pressure-trough area that accompanies 

 the front. The frontal surface then gradually 

 forms downward as the frontal system moves 

 away from the mountain, and it extends to the 

 earth's surface again. 



Therefore, the effect of the mountain range 

 on a warm front is to widen and prolong the 

 precipitation on the windward side of the range, 

 while on the leeward side the precipitation 

 band is narrowed and weakened, or dissolved. 

 (See fig. 14-21.) 



Mountain ranges have much the same effect 

 on OCCLUDED FRONTS as they do on warm 

 and cold fronts. Cold type occlusions behave 



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