SPECIMEN EXAMINATION FOR THIRD MATE 



On a weather map : 



(a) A region where the atmos- 

 pheric pressure is higher than that of 

 surrounding regions is called a 



(b) A region where the atmos- 

 pheric pressure is lower than that of 

 surrounding regions is called a 



Explain the pressure-volume rela- 

 tionship of gases if temperature is con- 

 stant. Either state in words or in math- 

 ematical notation. {Boyles Law) . 



State "Buys Ballot's Law". 



What is meant by the daily pressure 

 variation of the atmosphere? Where is 

 this weather phenomenon most charac- 

 tfiristic^ 



What is an "isobar"? 



What wind direction would be most 

 likely for a vessel at position "A" on 

 the weather chart sketched? 



(a) In the Northern Hemisphere; 



(b) In the Southern Hemisphere? 



What is the reading on the mercurial 

 barometer sketched below? 



-2a* 50 



3SL 



in* 



ffl' 4^t 



the 



What are the "horse latitudes"? 

 What is "wave direction"? 



(a) How is it recorded on 

 weather report? 



(b) How is the wave direction de- 

 termined? 



What are the "doldrums"? 



What is a "monsoon"? State its 

 causes. 



Make a rough copy of the sketch be- 

 low and indicate thereon the length 

 and height of the waves. 



Sketched below is a vertical section 

 through an air mass. Show how the iso- 

 bars on the weather map would repre- 

 sent such an air mass assuming that 

 the air mass is round and concentric. 

 Label appropriately the center of the 

 air mass. 



/////////////////////// 



What is an "anemometer"? 



What is a cold front? 



Cirrus clouds are composed of what 

 form of water vapour? 



Low clouds are defined as those 

 whose mean upper level is 6,500 feet. 

 Middle clouds are defined as those 

 whose mean lower level 6,500 feet and 

 whose mean upper level is 20,000 feet. 

 High clouds are defined as those whose 

 mean lower level is 20 000 feet. 



Classify as low, middle, or high the 

 following cloud forms : 



(a) Cirrus; 



(b) Nimbostratus; 



(c) Altostratus. 



690-515 O - 63 - 2 



