40 



UNITED STATES COAST GUARD 



Interpret the data provided by the 

 current rose shown from the Atlas 

 of Surface Currents, North Atlantic 

 Ocean. (H. O. Publication 571). 



DRIFT SCALE 



KNOTS 

 0.00 to 0.33 



0.34 to 0.66 



0.67 to 0.99 



1.00 to 1.33 



1.34 to 1.66 



OVER 1.66 



ii::::::::;i:::iinuii::iiiii|!:::|iiii[ii':|iiii| 



10 20 30 40 SO 60 70 BO 90 lOO 

 SCALE OF FREQUENCY PERCENTAGE 



What is the meaning of the term 

 "drift-ice" (or "pack-ice"), used in a 

 wide sense? 



Discuss the ice movements in the 

 North Atlantic. 



What is "fast-ice"? 



What is the best position for conning 

 a ship in ice? 



Explain the temperature volume re- 

 lationship of gases if pressure is held 

 constant. State in words or mathe- 

 matical notation. {Charles Law). 



How is the correction for an aneroid 

 bai'ometer noted and where should this 

 correction be posted? 



How often should the correction for 

 an aneroid be checked? 



How is the correction for an aneroid 

 determined? 



What action is taken by the weather 

 bureau when comparison indicates that 

 a bai'ometer is defective? 



What care must be given an aneroid 

 barometer to assure that it will retain 

 its calibration? 



State the precautions necessary to ob- 

 tain the correct sea level pressure when 

 using an aneroid barometer. 



Describe briefly the relationship be- 

 tween barometric pressures and the cor- 

 rections that must be applied to alti- 

 tudes of celestial bodies observed by 

 sextant. 



What is "vapor pressure"? 



A vessel's true course is 025° and 

 speed 22 knots. The apparent wind di- 

 rection is from NE. with 16 knots ap- 

 parent wind velocity. 

 REQUIRED: 



(a) The direction from which the 

 true wind is blowing. 



(b) The velocity of the true wind. 

 To what wind force on the Beaufort 



Scale do the following conditions cor- 

 respond? 



WIND SPEED 17 to 21 knots. 



SEA CONDITIONS Moderate 



waves, taking a more pronounced 

 long form; many white foam 

 crests; there may be some spray. 



What is a cyclone? 



Distinguish between a tropical cy- 

 clone and an extra-tropical cyclone. 



Describe squall lines and the condi- 

 tions associated with them. 



How can the barometer show the ap- 

 proach of a cyclone in the tropics? 



At what latitude (North or South) 

 does a tropical cyclone normally re- 

 curve? 



When do tropical cyclones usually 

 move at the slowest speed? 



State two reasons why tropical cy- 

 clones are divided into semi-circles, one 

 considered dangerous and the other con- 

 sidered navigable. 



What is the effect of current upon 

 the waves caused by a storm? 



What provides the energy for at- 

 mospheric disturbances along frontal 

 zones? 



What name is applied to tropical 

 cyclones in: 



(a) The North Atlantic. 



(b) The western North Pacific. 



(c) The Phillippines. 



(d) Western Australia. 



What causes the fog frequently as- 

 sociated with the frontal areas between 

 two air masses? Why are night condi- 

 tions more conducive to such fogs than 

 day conditions? 



Is fog more common and dangerous 

 along cold fronts or warm fronts? Why? 



