SPECIMEN EXAMINATION FOR THIRD MATE 



11 



Listed below are four months during 

 which tropical cyclones are known to 

 occur in the North Atlantic. Arrange 

 them with the month of highest fre- 

 quency of such storms first; the next 

 highest, next, etc. 



October 

 May 



September 

 June 

 Where do tropical cyclones form? 

 Why do tropical cyclones never form 

 closer than 5 degrees to the equator? 



The reported wind velocity in three 

 areas of a weather map are : 



Area 1 10 knots ; 



Area 2 20 knots; 



Area 3 30 knots. 



In which of the three areas will the 

 isobars be spaced closest? 



How should isobars be drawn on a 

 weather chart at a front? 



What is the angle that wind arrows 

 normally make with the isobars on 

 weather charts of ocean areas? 



In what direction does the wind blow 

 around a cyclonic storm in : 



(a) The Northern Hemisphere; 



(b) The Southern Hemisphere? 

 Why are anticyclonic areas normally 



accompanied by clear and fine weather, 

 whereas cyclonic areas are accompanied 

 by clouds, precipitation, and generally 

 foul weather? 



In the Northern Hemisphere, how 

 should a steam vessel maneuver in the 

 navigable semicircle of a tropical cy- 

 clone? 



If the wind velocity about the center 

 of a tropical cyclone is 75 miles an hour 

 and the speed of the storm along its 

 direction of advance is 25 miles per 

 hour, what is the maximum wind ve- 

 locity that may be encountered in the 

 dangerous semicircle, and what would 

 be the minimum wind velocity in the 

 navigable semicircle? 



What are the "roaring forties," and 

 where are they located? 



What weather conditions may result 

 from the movement of a warm air mass 

 over a colder sea surface? 



What are the Aleutian and Icelandic 

 lows? 



Is it possible for open isobars to ex- 

 ist, that is, isobars that do not form a 

 closed curve? Explain your answer. 



Are the Weather Codes provided by 

 the U.S. Weather Bureau solely for 

 use with United States weather reports, 

 or may they be used in coding and 

 decoding weather reports of other na- 

 tions? 



What is the Gulf Stream? 



Describe the California current and 

 state what segment it forms in the 

 general circulation of the waters of the 

 North Pacific Ocean. 



The direction of the wind is denoted 

 by the direction from which it is blow- 

 ing. How is the direction of a current 

 denoted? 



Under certain conditions in the 

 Northern Hemisphere it may be as- 

 sumed that the current sets 30° to the 

 right of the direction in which it is 

 driven by the wind and its velocity is 2 

 percent of the wind velocity. Basing 

 your answer on the foregoing state- 

 ment, estimate the direction and ve- 

 locity of the current that may be ex- 

 pected if the wind is from the South 

 South West at 35 knots. 



Given: 



Noon D. R. position ; 



Latitude 45°-06' South; 



Longitude 30°-51' West; 

 Noon observed position; 



Latitude 44°-54' South; 



Longitude 30°-51' West. 



Required: The set and drift of the 

 current, assuming a 24 hour run from 

 the previous noon. 



