9-50. Which type of tertiary circulation is 



characterized by a descending cold, dry 

 wind? 



1. Foehn wind 



2. Glacier wind 



3. Anabatic wind 



4. Katabatic wind 



9-56. Which of the following air mass source 

 regions is most closely associated with 

 the great desert areas of the world? 



1. cP 



2. mP 



3. cT 



4. mT 



9-51. 



9-52. 



9-53. 



Why are the leeward sides of steep moun- 

 tains more dangerous to aircraft than 

 the windward sides? 



1. Updrafts are more pronounced on the 

 leeward sides 



2. Friction is more pronounced on the 

 leeward sides 



3. Eddies tend to be more stationary on 

 the leeward sides 



4. Downdrafts are accompanied by more 

 pronounced eddies on the leeward sides 



Learning Objective: Recognize the 

 conditions that identify air masses 

 and the relationship of air mass 

 classifications and source regions. 



Which of the following terms is most 

 descriptive of the conditions of moisture 

 and temperature distribution in a body of 

 air that causes it to be called an air 



mass? 



9-57. What type of air mass has its source only 



9-58. 



9-59. 



Stable 

 Homogeneous 

 Unstable 

 Heterogeneous 



9-60. 



Air masses which are classified S are 

 found over the 



1. frozen polar seas 



2. frozen polar land areas 



3. southwestern United States 



4. land areas near the Equator 



in the region between 

 10° S lat? 



10° N lat and 



1. T 



2. A 



3. P 



4. E 



Learning Objective: Identify factors 

 which contribute to air mass modifi- 

 cation, and relate associated weather 

 conditions. 



Unstable air is characterized by 



1. clear skies 



2. radiation fog 



3. convective clouds 



4. stratiform clouds 



Which of the following air masses is 

 the coldest? 



1. Arctic cA 



2. Arctic mP 



3. Antarctic mP 



4. Antarctic cA 



What is generally the effect of the move- 

 ment of a cP air mass over a warmer land 

 surface? 



1. Fog 



2. Clear skies 



3. Cumuliform clouds 



4. High relative humidity 



9-54. A cPk air mass differs from a cPw air 

 mass in that it 



1. originates in polar regions 



2. originates over a continent 



3. is colder than the underlying surfaces 



4. is warmer than the underlying surfaces 



9-55. Which of the following conditions is most 

 favorable for air mass formation? 



1. Rapid motion of a body of air over a 

 uniform surface 



2. Stagnation of a body of air over a 

 nonuniform surface 



3. Rapid motion of a body of air over a 

 surface of uniform temperature and 

 humidity 



4. Stagnation of a body of air over a 

 uniform surface of uniform tempera- 

 ture and humidity 



9-61. A cPk air mass that flows over the Gulf 

 of Mexico in winter may be modified to 

 a/an 



1. E air mass 



2. cT air mass 



3. mP air mass 



4. mT air mass 



9-62. What is the most prevalent air mass in 

 the Southern Hemisphere? 



1. mT 



2. mP 



3. cP 



4. E 



56 



