SPECIMEN EXAMINATION FOR CHIEF MATE 



69 



How may swells indicate the ap- 

 proach of a tropical storm? 



How does the appearance of a trop- 

 ical cyclone, as depicted by the isobars 

 drawn on a weather map, differ from 

 the appearance of an extratropical cy- 

 clone originating in the middle lati- 

 tudes? 



Can storms with gale winds occur 

 under anti-cyclonic conditions with ris- 

 ing barometers? Explain your answer. 



The maximum height of storm waves 

 can be approximated by the formula: 



H = 1.5 V F where H is the height in 

 feet and 

 F is the fetch in 

 nautical miles 



Using this formula, determine the maxi- 

 mum height of storm waves that rnay 

 be encountered when a gale is blowing 

 from a direction in which the coastline 

 is distant 64 miles. 



In stormy weather at sea, is the di- 

 rection in which the waves are moving 

 always the same as the direction of the 

 wind? State the reasons for your an- 

 swer. 



In which semicircle of a ti'opical cy- 

 clone would a vessel be if the wind 

 shifted clockwise while ehe was hove to 

 in the Northern-Hemisphere? 



In the Southern Hemisphere, how 

 should a steam ves.^el maneuver if she 

 is on the storm ti-ack in front of the 

 center of a tropical cyclone? Answer in 

 full. 



Hove to in the Northern Hemisphere, 

 under tropical cyclone conditions the 

 barometer is rising and the wind is 

 shifting counter-clockwise. What is the 

 vessel's probable position relative to the 

 center of the storm and what action 

 should be taken to leave the storm area 

 as rapidly as possible? 



Explain the value of synoptic charts 

 of weather conditions for maneuvering 

 of vessels in extra-tropical storms. 



What are "foehn" and "chinook" 

 winds? 



State the three elements which com- 

 pose the pressure tendency. 



How is the pressure tendency deter- 

 mined: 



(a) With a barograph; 



(b) With a barometer? 



A vessel discharging cargo at anchor 

 observes an aj)proaching thunderstorm. 

 A flash of lightning is followed after 12 

 seconds by thundei-. Six minutes later 

 another flash of lightning is followed in 

 8 seconds by thunder after the second 



flash of lightning. How much time does 

 the vessel have to rig rain tents or cover 

 the hatches before the storm reaches 

 her? 



What is the effect of the earth's rota- 

 tion on the direction of current? 



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. 



(a) Basing your answer on the 

 foregoing statement, estimate the di- 

 rection and velocity of the current that 

 may be expected if the wind is from 

 the east at 35 knots. 



(b) Using the direction and veloc- 

 ity of the current estimated in (a), 

 find the course to steer to make good a 

 course of 210° if the speed of your 

 vessel is 12 knots. To solve this problem, 

 consider current only, disregarding any 

 other factors that may be involved. 



Give a general description of "Buys- 

 Ballot's law". 



What is a cold front? 



The direction of the wind in a cy- 

 clone is South. State the probable bear- 

 ing of its center from the ship in the 

 Southern Hemisphere. 



Describe cirro-stratus clouds. 



What is an occlusion in an extra- 

 tropical cyclone? 



"The three sketches below show the 

 symbols used on printed weather maps 

 to repi-esent cold fronts, warm fronts, 

 and occluded fronts at the surface. 



(a) What type front is represented 

 by sketch No. 1? 



(b) What type front is represented 

 by sketch No. 2? 



(c) What type front is represented 

 by sketch No. 3? 



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