7-64. Which of the following statements is cor- 

 rect concerning the tropopause, the 

 boundary between the troposphere and the 

 stratosphere? 



1. It is characterized by rapid tempera- 

 ture decreases with altitude 



2. It is characterized by rapid tempera- 

 ture increases with altitude 



3. It is not continuous from the Equator 

 to the poles 



4. It is uniformly thick 



7-65. The composition of the air above the 

 tropopause is about the same as that 

 below it with the exception of the 

 amount of 



1. oxygen 



2. nitrogen 



3. water vapor 



4. carbon dioxide 



7-66. Absorption of ultraviolet radiation by 

 ozone causes an increase in temperature 

 in the 



1. exosphere 



2. mesophere 



3. troposphere 



4. stratosphere 



7-67. Iri which layer does the atmospheric temp- 

 erature decrease to a minimum of about 

 -93° C? 



1. The stratosphere 



2. The thermosphere 



3. The exosphere 



4. The mesosphere 



7-68. Which atmospheric zone is noted for pro- 

 viding conditions favorable for increased 

 radio propagation? 



1. Stratosphere 



2. Ozonosphere 



3. Ionosphere 



4. Mesosphere 



44 



